recharge and remediation techniques · the geochemical application phreeqc, feasibility of...
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School of Engineering and Energy
Bachelor of Engineering (Hons) – Environmental Engineering
Development of Sustainable Groundwater Management Plan in
Yogyakarta:
Recharge and Remediation Techniques
Author: Nishi Verma
Supervisor: Dr. Martin Anda
In Conjunction with Dr. Yureana Wijayanti
Author’s Declaration
I hereby confirm that the thesis generated is my own work and the research
conducted is, to my knowledge, original and completed to the very best of my
abilities.
3
Acknowledgements
I would like to give a big thanks to Dr. Yureana Wijayanti for her ongoing help and
the residents of Yogyakarta for their kindness, cooperation and patience – my friends
Dwi and Bapak Muji for travelling across Yogyakarta. Thanks to my supervisor
Dr.Martin Anda for his help in crafting this thesis.
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Abstract
Since the 1970s, the Special Region of Yogyakarta in Indonesia has experienced
systemic deterioration of groundwater, by way of physical depletion and chemical
quality reduction. This is due to two main reasons – high groundwater abstraction
rates and disconnect between water network and at least 90% of the population. In
order to counteract these problems, this thesis looks at the development of a
sustainable groundwater management strategy in Yogyakarta through groundwater
recharge and remediation technologies. Similarities in site geology and
hydrogeology imply that the province is similar in nature to Perth, Western Australia.
As such, findings were also compared with technologies already being implemented
in Perth.
The region of study had an area of 155.08 km2 and was observed to have a decline
from the northern parts of the region to the south. Surface water flow travelled in a
south-westerly direction while groundwater flow travelled in a straight, north-to-south
direction. The presence of alluvial soils limited permeability and implied that both the
Yogyakarta-Sleman and Wates aquifers were semi-permeable, likening it the
confined Leederville and Yarragadee aquifers in Perth. A comparison of policy
framework between the two cities showed that Yogyakarta’s lack of government
enforcement and leniency with domestic residents led to significant over-abstraction
of the aquifer.
In order to develop a sustainable strategy, two main target areas were focussed on –
assessment of groundwater recharge and assessment of remediation technologies.
Parameters such as water depth, hydraulic conductivity and chemical constituents
were observed, along with a social survey detailing public perception of groundwater
pollution, government assistance and acceptance of potential remediation
techniques.
GIS image analysis of water depth and hydraulic conductivity suggested that the
placement potential aquifer recharge sites would be best suited in the north-east part
of the province, slightly outside the study area, to provide water for all. Geochemical
modelling suggested that mixing surface water with groundwater would not lead in
further pollution of the resource – as such two recharge schemes were proposed: an
infiltration basin and an injection well with stormwater detention tank. High hydraulic
conductivity in the study area favoured the instalment of injection basin using
rainwater and stormwater capture to recharge the aquifers.
Loss of groundwater samples during transportation from Yogyakarta to Perth
prohibited the analysis of treated groundwater via biosand filtration, activated carbon
filtration, reverse osmosis and chlorination. However, in its stead, a qualitative
analysis was carried out based on several key stakeholder values such as removal
efficiency (as derived from literature) and cost of implementation. The use of a social
survey identified the presence of different socio-economic classes, culminating in the
selection of two technologies – reverse osmosis for those from more affluent
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backgrounds and a hybrid biosand filtration and chlorination system for drinking
water for residents from lower socio-economic standing.
Summary of the findings found that aquifer recharge is a possible solution to
Yogyakarta’s high abstraction rates due to increased pollution. While there is a need
and want for remediation technologies, residents were hesitant to embrace their
potential without government assistance. Therefore, it is suggested that a subsidy
scheme be devised to encourage positive behavioural trends.
Future studies recommend that injection well trials are further developed in terms of
sizing. Remediation techniques should be transported from Indonesia for a technical
assessment on removal efficiency of contaminants.
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Table of Contents
Author’s Declaration ................................................................................................ 2
Abstract ..................................................................................................................... 3
Abstract ..................................................................................................................... 4
1 Introduction ......................................................................................................... 11
1.1 Aims and Objectives ....................................................................................... 12
1.2 Limitations and Constraints ............................................................................. 13
2 Site Description ................................................................................................... 14
3 Literature Review ................................................................................................ 18
3.1 Climate ............................................................................................................ 20
3.2 Topography ..................................................................................................... 22
3.3 Geology ........................................................................................................... 22
3.4 Hydrogeology .................................................................................................. 23
3.5 Policy & Regulation ......................................................................................... 24
3.5.1 Stormwater Implementation ...................................................................... 25
3.6 Groundwater Exploitation ................................................................................ 26
3.6.1 Abstraction Rates ..................................................................................... 27
3.6.1 Urbanization ............................................................................................. 28
3.7 Groundwater Recharge ................................................................................... 29
3.7.1 Urban Recharge ....................................................................................... 31
3.7.2 Artificial Aquifer Recharge by Stormwater ................................................ 32
3.8 Contamination ................................................................................................. 33
3.8.1 Total Organic Compounds ........................................................................ 34
3.8.2 Nitrogen .................................................................................................... 35
3.8.3 Acidification & Heavy Metals .................................................................... 36
3.8.4 Salinity ...................................................................................................... 37
3.8.5 Pathogens ................................................................................................ 38
3.9 Awareness ...................................................................................................... 39
3.10 Remediation Methods ................................................................................... 30
3.10.1 Granular Activated Carbon ..................................................................... 30
3.10.2 Biosand Filtration .................................................................................... 31
3.10.3 Reverse Osmosis ................................................................................... 31
3.10.4 Chlorine Disinfection ............................................................................... 31
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3.11 Conclusion .................................................................................................... 32
4 Methods ............................................................................................................... 41
4.1Water Depth and Hydraulic Conductivity .......................................................... 42
4.1.1Permeameter ............................................................................................. 42
4.1.2Computer Modelling ................................................................................... 42
4.2 Water Contamination ...................................................................................... 43
4.2.1 Social Survey ............................................................................................ 43
4.2.2 Sampling ................................................................................................... 44
4.2.3 Experimental Design ................................................................................. 44
5 Results ................................................................................................................. 45
5.1 Water Depth and Hydraulic Conductivity ........................................................ 45
5.2 Geochemical Modelling .................................................................................. 46
5.3 Social Survey ................................................................................................. 47
5.4 Groundwater Sampling ................................................................................... 47
6 Discussion ........................................................................................................... 50
6.1 Artificial Aquifer Recharge .............................................................................. 50
6.1.1 Site Suitability for Groundwater Recharge Location(s) ............................. 50
6.1.2 Site Suitability for Stormwater Addition ..................................................... 52
6.1.3 Recharge Options ..................................................................................... 53
6.1.4 Contrast to Perth and Wider Australia ..................................................... 55
6.2 Remediation Techniques ................................................................................ 56
6.2.1 Social Survey ............................................................................................ 56
6.2.2 Presence of Contaminants ....................................................................... 57
6.2.3 Assessment of Remediation Technology .................................................. 59
7 Conclusion ........................................................................................................... 62
8 Recommendations for Further Study ................................................................ 64
9 References ........................................................................................................... 66
Appendix 1 – Tables & Measurements ................................................................. 74
Appendix 2 – Design Parameter for Aquifer Recharge ....................................... 75
Appendix 3 – Breakdown of Costings .................................................................. 76
Appendix 4 – Sampling Procedures ..................................................................... 77
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List of Figures
Figure 1 - Map of Five Regencies of Yogyakarta ................................................... 14
Figure 2 – Study Area of Yogyakarta ...................................................................... 15
Figure 3 – Contour Map of Study Area ................................................................... 16
Figure 4 – Frontal View of Surface ......................................................................... 16
Figure 5 – Rainfall Data of Yogyakarta from 1984 to 2005 .................................... 21
Figure 6 – Rainfall Distribution along the Perth Basin ........................................... 21
Figure 7 – Hydrogeological Model of Yogyakarta ................................................... 23
Figure 8 – Objectives of Stormwater Management ................................................ 25
Figure 9 – Dependence on Different Sources of Water in Perth ............................. 28
Figure 10 – Model of Different Inputs and Outputs in Yogyakarta .......................... 29
Figure 11 – Model of TOC Contamination in Yogyakarta City ................................. 32
Figure 12 – Correlation of Population Density with Nitrogen Contamination in
Yogyakarta ............................................................................................................... 34
Figure 13 – Coliform Levels in Areas of Yogyakarta from 1999 to 2000 ................. 36
Figure 14 – Groundwater Sustainability Infrastructure Index 2000 ......................... 37
Figure 15 – Household Application for Activated Carbon Filter .............................. 38
Figure 16 – Schematic of Biosand Filter ................................................................. 39
Figure 17 – Locations Visited and Monitored ......................................................... 41
Figure 18 - Permeameter ...................................................................................... 42
Figure 19 – Map of Water Depth ............................................................................ 45
Figure 20 – Hydraulic Conductivity (m/day) in Yogyakarta ..................................... 46
Figure 21 – Identification of Locations with Lowest Water Depths Against
Conductivity ............................................................................................................. 47
Figure 22 – Infiltration Rate VS Hydraulic Conductivity .......................................... 51
Figure 23 – Buffer Zones and Proposed Placement of Recharge ........................... 52
Figure 24 – Schematic of Infiltration Basin ............................................................. 53
Figure 25 – Schematic of Proposed Water Detention and Injection ....................... 54
Figure 26 – Correlation between Chloride Ions and Total Dissolved Solids ........... 58
Figure 27 – Correlation Between EC and TDS in July ............................................ 58
Figure 28 – Correlation Between EC and TDS in September ................................. 59
Figure 29 – Schematic of Hybrid Biosand and Chlorination .................................... 61
Figure 30 – Side View of Water Sensor ................................................................. 77
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Figure 31 – Bottom View of Water Sensor .............................................................. 77
Figure 32 – Initial Observation of Alkalinity as Outlined in Step 4 .......................... 78
Figure 33 – Observation of Total Alkalinity as Outlined in Step 5 ........................... 78
List of Tables
Table 1 - Comparison of Cities Relying on Shallow Aquifers .................................. 18
Table 2 - Physical Characteristics of Aquifers in Perth Basin .................................. 24
Table 3 - Table of Urban Recharge Parameters in Yogyakarta .............................. 30
Table 4 - Risk Matrix of Organic Contaminaton in Yogyakarta ............................... 32
Table 5 - Comparison of Nitrogen Guidelines ......................................................... 33
Table 6 - Template of Questionnaire Asked of Local Residents ............................. 43
Table 7 - Distribution of Species in Groundwater Wells and Corresponding Molarities
................................................................................................................................. 47
Table 8 - Social Survey of Residents on Groundwater Contamination Issues ........ 48
Table 9 – Chemical Constituents ............................................................................ 49
Table 10 - Effect of Different Hydraulic Conductivities on Infiltration Rate .............. 51
Table 11 - Comparison of Infiltration Basins versus Injection Wells ........................ 54
Table 12 - Comparison of Remediation Technologies ....................................... 59Fig
Table 13 - Superficial Chemical Analysis of Groundwater in Yogyakarta ................ 74
Table 14– Rainwater Analysis of Yogyakarta ......................................................... 74
Table 15 - Peak Flow Rate of Stormwater Using Infiltration Basin .......................... 75
Table 16 - Peak Flow Rate of Stormwater Using Injection Wells via Stormwater
Detention Tank ........................................................................................................ 75
Table 17 - Costing Distribution of Injection Well and Subsequent Stormwater Tank
................................................................................................................................. 76
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1 Introduction
Since 1970, Yogyakarta has been experiencing high population growth, putting
immense pressure on the government to provide safe water to all residents (D. P.
Putra 2011). Most of the water that is used is derived from shallow aquifers
underneath the ground – however, in recent years it has become apparent that
increasing population has led to water scarcity in this province due to lack of
sufficient groundwater reserves. This can be attributed to one of two causes. One
reason is that only 9% of the population is connected to the sewerage network,
leaving the remaining public to dispose of industrial, agricultural and domestic waste
into groundwater wells without prior treatment (Kamalyan n.d.). The presence of
contaminants such as chloride, nitrate and E. coli in the groundwater streams have
made the resource difficult to use. The second reason is due to high groundwater
abstraction rates, especially in Yogyakarta’s urban areas, which have significantly
depleted reserves, which have made it difficult to cater to a population of roughly 4
million people (Putra and Baier 2007). This is due to increased settlement, which
was found to decrease rainwater infiltration rates by 9.25% (Manny, et al. 2016) .
This study is mainly focused on the managing of groundwater in a sustainable
fashion for the future. The core of this research was focused on Yogyakarta province
and how best to encourage sustained aquifer recharge across all regions. Using
computational models such as GIS software (i.e. ArcGIS and Terrset) and the use of
the geochemical application Phreeqc, feasibility of groundwater recharge was
determined. Composition of groundwater, including both physical and chemical
parameters, were a vital point of interest as treatment options of contamination was
a target area of this study. Use of stormwater as an input into groundwater was
considered, in order to better manage severe storm events. Government assistance
and policy recommendations have also been suggested to improve behavioural
patterns of residents and to maintain groundwater for a long-term period.
The findings of this research were also compared with current practices in Perth to
assess whether the proposed solutions will be viable or not, as both cities had similar
physical attributes. Essentially, this study acted as a first step in the development of
an enduring strategy to providing a water secure future to the residents of
Yogyakarta province.
1.1 Aims & Objectives
The main aim of the project was to develop a sustainable groundwater management
strategy in Yogyakarta, with the primary focus being to replenish and remediate the
aquifers in the regions, in order to provide safe water to all. Not only were the
technical components to this plan investigated, but policy & regulation, behavioural
trends and economics were also considered in formulating viable options. The
results also provided an insight into using tactics currently being applied in Perth,
owing to similar conditions in both cities.
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The objectives of this study are outlined below.
Establish an understanding of the current situation of groundwater extraction
and contamination in Yogyakarta in contrast to Perth, especially in response
to a burgeoning population.
Conduct investigations on the depth and hydraulic conductivity of aquifers in
the five regencies.
Determine the composition of these aquifers in terms of salinity, lone ion
concentrations, pH, conductivity and alkalinity.
Determine feasibility of managed aquifer recharge using stormwater/surface
runoff to replenish aquifers. This will culminate in a manageable, long-term
solution to water crises plaguing the province. Examples of current sites in
Perth, and indeed greater Australia, will be discussed to aid in the
determination of a viable recharge strategy.
Qualitatively review and discuss the application of remediation techniques in
Yogyakarta province as a whole in order to eliminate harmful contaminants
that may have an adverse effect on the population.
1.2 Limitations & Constraints
This project encountered several hurdles while the author carried out this study.
Many of these were specifically related to carrying-out the study in Indonesia and the
lack of resources available there. Information was more readily available in Perth,
allowing for an excellent comparison of resources between both Australia and
Indonesia; however the study could have been made more robust had these assets
been available. The constraints experienced in this study are as listed below:
Overseas coordination of study
Customs/immigration issues with transportation of groundwater samples.
Lack of information concerning governmental policy and regulation in
Indonesia.
1.2.1 Overseas Coordination of Study
Conducting this thesis overseas proved a challenge as responsibilities had to be
juggled between those in Australia and also in Indonesia. As the author lived in
Australia, they were only in Yogyakarta for a limited period of time i.e. three weeks.
While this was ample time to conduct a preliminary investigation into behavioural
patterns of residents in Yogyakarta and record physical parameters including
groundwater depth and superficial composition, laboratory analysis waiting time in
Indonesia exceeded a month, which was not within the time range of the author.
With the help of colleagues in Yogyakarta, a detailed laboratory analysis was able to
be carried out. This, however, required extensive time, over-reliance on external
sources and monetary concerns, which hindered results analysis until all data was
made available.
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1.2.2 Customs/Immigration Issues with Transportation of Groundwater
Samples
Initial laboratory analysis of groundwater samples was conducted in Yogyakarta to
avoid any contamination that may have occurred while travelling. This was limited to
only a limited number of constituents being tested. Afterwards, the sampling program
involved the transportation of eighteen groundwater samples to Perth for further
analysis. This included 500 millilitre sub-samples from each location to be put
through various treatment methods. However, the Department of Agriculture and
Water Resources was experiencing a backlog for several months at the time of
lodgement of the permit for overseas transportation. Submitted at the end of August,
only four samples arrived of the eighteen that were requested from Indonesia – the
remaining fourteen were misplaced and had not been recovered. It was advised by
the Department that a new permit application would not be approved quickly, and
hence, it was decided that the remaining samples will not be requested again. This
has resulted in only a quantitative analysis of results taken prior to arrival, and thus
led to a qualitative discussion on treatment methods.
1.2.3 Lack of Information Concerning Governmental Policy and
Regulation in Indonesia
Policy regarding groundwater specific to Yogyakarta was difficult to find. Federal acts
were found pertaining to abstraction rates and technical guidelines for contamination
were also used. However, there was no substantial information on current measures
by the government to encourage water protective measures (Japan International
Cooperation Agency 2008).
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2 Site Description
This study was focussed on the five regencies of Yogyakarta, as shown in Figure 1
below. Of the five regencies, three border the Indian Ocean. The northern most tip of
the province is where the active volcano, Mount Merapi, is located. The five
regencies are listed as follows:
Yogyakarta city – urban city centre and administrative division.
Sleman – northern region of the province.
Gunungkidul – eastern area of the province.
Bantul – southern part of the province.
Kulon Progo -western division of the province.
Of the five divisions, three border the Indian Ocean.
Figure 1 – Map of Five Regencies
of Yogyakarta (D. P. Putra 2011)
Gunungkidul
Yogyakarta City
Bantul
Sleman
Kulon Progo
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The site study area covered a total area of 155.08 km2 and spanned from the
western location of Kulon Progo regency to north-eastern part of Sleman regency. It
also extended to the southern Bantul regency, essentially allowing for a complete
study of the entire province to be undertaken and all five regencies as per Figure 1 to
be studied, not just the urban city centre. Figure 2 shows the study area.
The texture of the soil consisted of a mix of clay and sand, with sandy loam being
observed near the city centre and Sleman regency. The gradient of the area was on
a gradual decline the further south the author travelled. Topography was largely flat,
attributed to urban developments, particularly in Yogyakarta city. However, the
northern boundaries, and most especially the north-eastern regions, were located on
hilly terrain at high elevations.
The following figures were created using modelling software to determine the
elevations of surface terrain in Yogyakarta. Using Google Maps, elevation was
determined and then exported to the program Surfer to create contour maps. This is
shown in Figures 3 and 4. Interestingly, a frontal view of the study area (Figure 3)
showed a gradual decline towards the western region of Kulon Progo.
Figure 2 – Study Area of Yogyakarta
Province
16
Figure 3 – Contour Map of Study
Area (m)
Figure 4 – Frontal View of Surface
Elevation Model
Sleman
Yogyakarta City
Kulon Progo Bantul
Latitude (degrees)
Lo
ngitu
de
(de
gre
es)
Heig
ht (m
)
Heig
ht (m
)
Latitude (degrees)
Lo
ngitu
de
(de
gre
es)
17
This suggests that surface water (i.e. rainwater and stormwater) flows in a south-
westerly direction as indicated on Figure 3 by the red arrow, opposed to groundwater
which flows in a north-to-south direction, as shown by the yellow arrow.
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3 Literature Review
Shallow groundwater aquifers are a water resource commonly used in a number of
cities around the world, especially in the case where the aquifer directly underlies the
city in sandy and/or loam soils. This is the case in Yogyakarta, Indonesia and Perth
in Australia. Accordingly, these aquifers are highly vulnerable to contamination from
urban and agricultural activities as well as abstraction beyond sustainable yield.
Table 1 shows a comparison of Yogyakarta, Perth and other cities that share the
characteristic of having shallow aquifers, their uses and the issues currently being
faced.
Table 1 - Comparison of Cities Relying on Shallow Aquifers
City Uses Issues
Perth Agricultural purposes.
Irrigation.
Rising salinity (Bennett and Macpherson 1983).
Over-Abstraction (Tapuswan, Leviston and Tucker 2009)
Yogyakarta Drinking and domestic purposes.
Agricultural activities.
High concentration of nitrates and heavy metals (D. Putra, The Impact of Urbanization on Groundwater Quality 2007).
Over-abstraction (Putra and Baier 2007).
Redwood, California Outdoor use for irrigation for both commercial and residential use.
Declining water quality caused by salinity intrusion.
Locations where there is no shallow aquifer are constantly under water stress (Schmidt n.d.).
Moradabad, India Mostly private wells are used in residences.
85% used for agriculture while remaining is used for
One of the most polluted centres in the Gangetic plain.
High concentration of Na, K, Cl, SO4 and NO3.
Alkaline, Hardness
19
industrial/residential purpose.
and total dissolved solids (Verma 2008).
Doula, Cameroon Allocation mostly goes towards domestic and drinking purposes, further compounded by a severely dry climate.
Acidification – depletion of HCO3
results in low acid buffer.
Increased mobility of Al, Pb, Cu, Zn and Mn (Takem, et al. 2015).
Although much research has been conducted on the state of groundwater in
Yogyakarta, a relevant water management strategy to deal with deteriorating
quantity and quality has not been finalized yet. At least 90% of the population
continue to use some sort of on-site sanitation system, introducing potentially
pathogenic organisms to the aquifers, combined with industrial waste including
organic contaminants and heavy metal pollution (Kamalyan n.d.). Coincidentally,
high groundwater abstraction rates, especially in Yogyakarta city, have significantly
depleted existing reserves and made it difficult to cater to a population of four million
people (Putra and Baier 2007). The impact of these two issues on groundwater will
form a critical part of this literature review.
A portion of this literature review is also concerned with groundwater in Perth, in
order to make comparisons with Yogyakarta. The expected population of Perth in
2050 is expected to reach 3.5 million (News 2016). While several government
agencies and environmental groups continue to raise awareness on the issue of
water scarcity and importance of policy, contamination and over-abstraction are
increasing in the city and its surrounding suburbs. Some studies have found that
declining rainfall and extensive land use & excavation have led to widespread
contamination (Wong, et al. 2004).
This literature review will be a summary of different categories presently affecting
groundwater in both Yogyakarta and Perth. Points of interest will be:
Identification of similarities/differences in physical parameters.
Identification of problems being faced in both regions, including behavioural
trends and policy and regulation.
Identification of main areas to target if a sustainable groundwater
management strategy is to be achieved.
Identification of recharge technologies and treatment methods to effectively
eradicate contaminants from groundwater
By formulating a relevant groundwater management scheme, using insights from
Perth’s experiences and projects such as Beenyup wastewater treatment plant and
Hartfield Park in Kalamunda, Yogyakarta may also be able to replicate methods in
Perth, as both cities share similarities. Since the situation in Indonesia is of poorer
20
quality, especially in terms of pollution and public health, it is imperative that the
recharge and remediation methods proposed can be used to overcome the negative
consequences that residents in the province are facing.
3.1 Climate
A study (Karamouz 2013) noted that there were three main effects of climate change
on groundwater conditions, which can be applied in Yogyakarta and Perth. The
following are conditions summarized from this article:
1. Changes in timing of weather patterns, causing erratic rainfall and thus having
an adverse effect on stability of groundwater recharge.
2. Changes in interaction of groundwater in terms of human use for industrial
and agricultural purposes.
3. Changes in surface water patterns and receding waters (in case of natural
disasters).
The mean temperature in Yogyakarta is 27.3ᵒC (Manny, et al. 2016) and average
annual rainfall is estimated to be 2450 mm/annum (D. Putra, Integrated Water
Resources Management in Merapi-Yogyakarta Basin 2003). Rainfall continues to
decline, as shown in Figure 5 below (Manny, et al. 2016). This, in conjunction with
gradual warming, has led to an inability to sufficiently recharge aquifers.
The temperature in Perth ranges from 12-25⁰C (Australian Bureau of Meteorology
2018). Although Perth enjoys a temperate climate of hot, dry summers and cold, wet
winters, it has been noted that due to the drying impact caused by climate change,
annual rainfall in the region has decreased by 10 to 15% since 1975 (refer to Figure
6), culminating in a decrease in runoff by almost 50% (CSIRO 2009). The effect of
climate in Perth is minimal as aquifers the Leederville and Yarragadee aquifers are
deep – as such evapotranspiration will only contribute to a 2% loss in groundwater
(D. McFarlane, Will Perth have Enough Water for its Diverse Needs in a Drying
Climate? 2016). This is a trend that is similarly followed in Yogyakarta, although
extreme weather events are not prevalent in south-western Western Australia.
21
Figure 5 - Rainfall Data of Yogyakarta from
1984 to 2005 (Manny, et al. 2016)
Figure 6 - Rainfall Distribution
along the Perth Basin (CSIRO
2009)
22
3.2 Topography
The Special Region of Yogyakarta is located on the Central part of Java Island, with
five regencies constituting the whole of the province:
Sleman
Kulon Progo
Bantul
Gunungkidul
Yogyakarta City
The total combined area is 3186 km2 (International Congress for School
Effectiveness and Improvement 2014). Physically, it lies between Mount Merapi, a
dormant volcano, to the north and the Indian Ocean to the South. It has an elevation
of 114 metres above sea level (Ratha, Putra and Hendrayana 2012). The region is
on a decline towards the ocean, thereby affecting the flow of groundwater, which
travels from north-to-south. The terrain is also dominated by hills, although
composition varies. There are volcanic and sedimentary hills in the north and east
while limestone hills are located in the west (Kamalyan n.d.).
The Perth Basin is a sedimentary basin stretching roughly 1300 kilometres along the
southwestern coastline of Western Australia. It was formed from the separation of
Australia from other continents in the early Cretaceous period. A vast portion of it is
below sea level, extending well past dry land where water is 4.5 kilometres deep
(Geoscience Australia 2018). Widespread erosion caused by shifting movements
during the early Cretaceous period have altered the formation of several features
along the coastline, as well as forming several troughs as well, such as the
Dandaragan Trough (Geoscience Australia 2018).
3.3 Geology
Most of the soils in Yogyakarta are alluvial in nature i.e. they are made up of clay, silt
and sand, mainly from redeposited volcanoclastic materials (Manny, et al. 2016).
Clay content increases in southern regions, such as in the Bantul regency. The city
itself, however, consists of more sandy loam soils than clay (Japan International
Cooperation Agency 2008).
Geology of the Perth Metropolitan region is composed of sediments of the Swan
Coastal Plan. There are four main geological systems - these are as listed below
(Salama, et al. 2002) (McPherson and Jones n.d.):
Guildford clay (east) – clays.
Bassendean dune system (middle) – aeolian sands, with calcareous and,
quartz sand and fine-grained black minerals.
Spearwood dune system (middle) – slightly calcareous aeolian sand.
Quindalup dune system (coastline) – consists of limestone and quartz beach
sand.
23
The surface geology of the Perth Basin is much more complex than that of
Yogyakarta, where soils are mostly uniform due to volcanic activity long ago.
However, similar clay and sandy-loam textures that the two cities would imply that
groundwater flow through these surface networks would be fairly similar.
3.4 Hydrogeology
Yogyakarta has two main aquifers that have been officially acknowledged by the
Indonesian government – Yogyakarta-Sleman and Wates, with the former being the
main one (Thin, et al. 2018). The Yogyakarta-Sleman aquifer is a semi-aquifer which
is partially confined by sandy loam soil prevalent in the region. Aquifer depth is fairly
shallow. It can be split into upper (Sleman) and lower (Yogyakarta city) regions,
interbedded with materials such as sands, gravels, silt, clays and lenses of breccia.
Volcanic activities caused by Mount Merapi in the northern part of Yogyakarta
caused the formation of many of the layers. Igneous rock forms the bedrock called
the ‘Sentolo’ formation and limestone is present in varying quantities underneath the
aquifer; however, lower permeability soils as mentioned in Geology act as a resistant
to groundwater flow. Thickness of the aquifer is roughly 45 metres and hydraulic
conductivity is estimated to be 8.64 metres/day (Iqbal, et al. 2013).
Wates aquifer system in Kulon Progo region is characterized by sand and gravel
interspersed with alluvial deposits all throughout (Thin, et al. 2018). Groundwater
flows from the Sentolo Hills to Wates region and slightly changes to an easterly
direction before carrying its water towards the ocean. It is classified as a minor
aquifer with limited permeability and storage (Partners 1984). Thickness of the
aquifer ranges up to 30 metres (Thin, et al. 2018).
In both cases, groundwater flows from north to south, with the gradient becoming
steeper in southern, coastal parts of the region (Ratha, Putra and Hendrayana
2012). Figure 7 shows the two aquifers in a cross-sectional diagram.
Figure 7 - Hydrogeological
Model of Yogyakarta
(Iqbal, et al. 2013)
24
Recharge of aquifers in Perth occurs mostly through natural precipitation events
(CSIRO 2009). As they are layered under one another, recharge of lower aquifers is
dependent on factors such as permeability and porosity of water flow through the
aquifer above. The superficial aquifer itself is the most permeable – however this
parameter is known to decrease as one goes underground, being dependent upon
aquifer depths (Pujol, Ricard and Bolton 2015). The physical characteristics of these
three aquifers are expressed in Table 2 below.
Table 2 - Physical Characteristics of Aquifers in Perth Basin
Name of Aquifer
Nature of Aquifer
Aquifer Depth (m)
Composition Groundwater Age (Years)
Superficial Unconfined 100 Sand, silt and clay
2000 (Thorpe and Davidson 1991)
Leederville Confined 400 Shale and siltstone
1900-36800 (Thorpe and Davidson 1991)
Yarragadee Confined 1725 Shale beds and sandstone
600-37000 (Thorpe and Davidson 1991)
The limited permeability of the two aquifers in Yogyakarta are most similar to the
Leederville and Yarragadee aquifer, which are confined. Limited permeability makes
it difficult to recharge these aquifers, which would apply to Yogyakarta as well, given
their geological soil structures are similar. So, any recharge techniques proposed for
Yogyakarta province could potentially be based on ones applied in Perth due to
similarities in hydrogeological properties.
3.5 Policy & Regulation
Water restoration in Indonesia started on a national scale, with the development of a
water resources management team (TKPSDA) (Azdan 2011), which is responsible
for formulating new national policies on water management. Law No. 7/2004 details
seven government regulations detailing how water resources should be maintained
in a cooperative manner with public participation (Hadipuro 2010). Pertaining
specifically to groundwater extraction, there are two different legislations that have
been implemented, both originating in the Central Java region of Indonesia. They
are:
Central Java Provincial Act No. 6/2002.
Central Java Provincial Act No. 7/2002.
As per article 2 of Act No. 6/2002, those who extract water at less than 100
m3/month and/or have less than a two-inch diameter pipe for groundwater levels for
domestic/drinking use are not required to have a water abstraction permit (Azdan
2011). Article 4 of Act No. 7/2002 also states that groundwater extraction based for
domestic use cannot be subject to a groundwater abstraction tax (Hadipuro 2010).
25
Residents have bypassed laws continuously, with many areas of Yogyakarta
continuing to use more than 100 m3/month (Ratha, Putra and Hendrayana 2012).
With no permits, taxes, metering or penalties, excessive abstraction of groundwater
places into doubt an effective management strategy being implemented in
Yogyakarta.
In Perth, there are several policies in place to ensure groundwater protection. Firstly,
during the planning stage of any new site, it must be proven that there is approval of
land use to be built in groundwater protection areas and that there are water
catchments and protection zones to combat extraction of this resource (Government
of Western Australia 2018). An example of this is the State Planning Policy for
Gnangara Groundwater Protection (Department of Planning Lands and Heritage
2005). For locations that extract groundwater from bores for irrigation, there must be
a proper license and an assessment must be conducted to assess the depth of the
bore (Water Corporation 2018).
Another increasing focus is on the implementation of stormwater regulations to
restore the water balance.
3.5.1 Stormwater Implementation
Stormwater forms an essential part of the urban hydrological cycle as the inputs and
outputs of this resource are often wasted because of ill-devised water networks.
Stormwater guidelines and regulation encourage the design of drainage networks to
deliver stormwater runoff back to the hydrological cycle (Phillips, van der Sterren and
Argue 2016). Stormwater design processes must be considered in terms of flooding,
drainage and water quality. There are three main objectives in achieving sound
stormwater management (Phillips, van der Sterren and Argue 2016) – this is shown
in Figure 8.
Figure 8 – Objectives of Stormwater Management [33]
26
This approach is widely supported by Water Corporation and the Department of
Water and Environmental Regulation; the latter have laid out a decision process for
stormwater management, highlighting key objectives (Department of Watern and
Environmental Regulation 2017):
Replication of hydrological processes.
Prevention of pollution.
Integration of stormwater systems into the urban development.
Development of systems able to respond to environmental, social and
economic restraints.
Heavy flooding in 2010/11 in Queensland and Victoria led to the development of
these guidelines and several policies to not only improve water management, but in
doing so, prevent the loss of property and life in severe storm events. As such in
Western Australia, Water Corporation have developed a stormwater management
manual that assists in the planning of stormwater infrastructure and contingency
plans (Department of Environment 2004)
In Indonesia, although there are policies on stormwater management, there is no
code of practice on the design and implementation of stormwater injection. In 2013, it
was recorded that only 1.16% of local/city councils had a stormwater management
policy (ASEAN 2015). This is a direct by-product of not having the appropriate
framework to encourage and sustain development of these networks.
A comparison of these different regulatory frameworks shows that there is not
appropriate implementation of water rights in Yogyakarta, and indeed, Indonesia as
a whole. In Perth, everybody is required to be approved should they extract water or
trespass on any groundwater zones, whether they be industry or domestic users.
One of the main faults in Indonesia is that the law differentiates between companies
and residents. As such, residents are not required to hold permits, as supported by
article 8, clause 1, Law N. 7/2004 (Hadipuro 2010). In order to achieve groundwater
sustainability, this issue must be addressed with urgency. The lack of stormwater
policy in Indonesia is also inadequate. Lack of proper drainage and diversion
facilities could be the cause of flash flooding in urban centres. Stormwater as a
source of potential recharge will be discussed in this chapter and assessed in
Chapter 6.
3.6 Groundwater Exploitation
Like many parts of Indonesia, Yogyakarta faces problems in managing the volume of
groundwater being abstracted, leading to this resource becoming overexploited
(Putra and Baier 2007). This is due to growing population in the area. Going as far
back as the 1980s, educational institutions, hotels and houses have been built to
promote the city’s activities (Kamalyan n.d.). As a result of increased land use and
burgeoning population, there is increased groundwater pumping all throughout the
region. In some areas, the water table drops at a rate of 0.3 m/year (Muryanto 2014).
27
The main uses for the groundwater in the Special Region of Yogyakarta are (Putra
and Baier 2007):
Drinking Water in Rural Areas
Drinking Water in Urban Areas
Irrigation Water
In Australia, groundwater is becoming an increasingly important resource as surface
water resources decline. The groundwater in the metropolitan city of Perth currently
constitutes 2/3 of all water in the state. (Geoscience Australia 2018). Similar to
Yogyakarta, Perth is also experiencing a rapid increase in population and to cope
with this, more water is required. In the past decade, Perth has had to access
coastal aquifers and deeper aquifers than the superficial one closest to the surface
(Geoscience Australia 2018). It is often combined with seawater desalination to meet
the demands of many industrial/agricultural needs and irrigation purposes.
3.6.1 Abstraction Rates
It has been stated that groundwater is being extracted at a rate of 45000 m3/day
(Iqbal, et al. 2013). This equates to a rough total of 16.4x106 m3/annum. It was also
predicted that safe abstraction rates were not to exceed more than 6.5x106
m3/annum (D. Putra, Integrated Water Resources Management in Merapi-
Yogyakarta Basin 2003). As evidenced by these polarizing figures, the extraction
rates currently being used in the province far exceed the safe levels estimated for
use.
There are no published extraction rates or figures for the Perth metropolitan region
or surrounding areas. However, Figure 9 shows the allocation of water sources in
Perth – there is a clear trend that groundwater is being used more and more. So, it
can be inferred that abstraction rates are gradually increasing.
28
3.6.2 Urbanization
A commonly accepted theory is that variations in groundwater in Yogyakarta are
caused by high abstraction rates and domestic sources of recharge (Putra and Baier
2007). From this, two main points can be taken. These are as follows:
1. The introduction of domestic/industrial recharge affected the existing
groundwater cycle in urban settings.
2. The aforementioned domestic sources caused large contamination.
Historical reports support that Yogyakarta has experienced systemic deterioration in
water quantity since the 1990s due to increased land use, thereby decreasing
natural recharge in the area (Muryanto 2014). In 1998, a new water supply and
sanitation system was installed. However, this only services 9% of residents
(Sukarma and Pollard 2002). As such, the remaining population continues to use on-
site sanitation systems.
Figure 10 provides illustrates the inputs and outputs into the groundwater. The
extraction and loading points shown in the diagram is representative of the current
situation universally, but most especially in Yogyakarta.
1 Figure 9 - Dependence on Different Sources of Water in Perth (D.
McFarlane, Will Perth have Enough Water for its Diverse Needs in a
Drying Climate? 2016)
1 Please Note: Due to poor quality of original image, note that red bars correspond to dams,
green to groundwater and blue with desalination.
29
Unlike Yogyakarta, however, the water network in Perth is well connected and hardly
has any sewerage leaks that would introduce water full of harmful bacteria to aquifer
below (Appleyard 1995). All road runoff goes to infiltration basins – so more or less,
there is no loss of rainfall. However, the disparity between non-urban and urban
areas is large. Groundwater recharge in suburbs is roughly 15-25%, whereas in the
city, this figure is 37%. This is due to land clearing, stormwater infiltration and
importation of water (Appleyard 1995). Land use and clearing works in Perth
continue to decrease recharge of groundwater from natural occurrences such as
precipitation events.
3.7 Groundwater Recharge
Groundwater recharge is the replenishment of underground aquifers with inputs of
water. These inputs can range from freshwater sources such as rain to industrial
waste liquids and sewerage, raw or treated. There are several ways total
groundwater recharge can be calculated. A study on water supply schemes in
Yogyakarta used (1) (Japan International Cooperation Agency 2008), as follows:
U = P – ETr – Ro
Where U = Groundwater Recharge (mm/year) P = Precipitation (mm/year) ETr = Evapotranspiration (mm/year) Ro = surface runoff (mm/year)
(1)
Figure 10 - Model of Groundwater Inputs and
Outputs in Yogyakarta (Putra and Baier 2007)
30
Urban Recharge
An equation calculating total urban recharge, including leaks, sewage and industrial
effluent (Putra and Baier 2007) is shown in (2).
UU = LI + LS + LW + Lnd
Where UU = Total Urban Recharge LI = Leakage from Water Supply System LS = Leakage from Sewer System LW = Non-Exported Domestic Waste Water Lnd = Non-Domestic Wastewater
Table 3 below illustrates the breakdown of urban groundwater recharge in Yogyakarta.
3.7.1 Artificial Aquifer Recharge by Stormwater
Either forced or passive injection of treated water into groundwater reserves can
increase water quantity to increase longevity of an aquifer. They do not require
complicated and costly technologies, which is ideal for medium sized communities
(Hofkes and Visscher 1986) and can instead use passive techniques such as sump-
catch basin on a gradient to encourage stormwater collection. A study in the
Netherlands found that recharge schemes economically viable, most especially in
developing countries (Hofkes and Visscher 1986). Yogyakarta contains semi-
confined aquifers, which proves a challenge as direct infiltration cannot occur.
Several technical factors must be taken into account to assess viability of an artificial
recharge scheme:
Retention time
Permeability
Storage capacity
(2)
Table 3 - Table of Urban Recharge Parameters in Yogyakarta (Putra
and Baier 2007)
31
Infiltration Rate, and;
Porosity
There are several ways of recharging an aquifer. Since the aquifers in Yogyakarta
are unconfined in nature (Iqbal, et al. 2013), there will be a focus on infiltration
basins and induced recharge.
Due to water stress, Perth has developed several artificial recharge schemes that
would replenish groundwater resources. The sand, gravel and limestone composition
in Perth has likened artificial aquifer recharge to slow sand filtration and so infiltration
galleries are popular. However, they get clogged much more easily - an infiltration
gallery in Floreat, Perth underwent excessive clogging due to the high concentration
of sediments (McFarlane, et al. 2015).
Hartfield Park, in the city of Kalamunda, utilized filtered stormwater to inject into the
Leederville aquifer. Between June and October 2016, the injection bore captured
and successfully stored 4,400 kilolitres into the Leederville aquifer (City of Kalmunda
2018).
3.8 Contamination
3.8.1 Total Organic Compounds
The risk of total organic compounds (TOC) entering the groundwater stream poses a
threat to humans as taste, odour, colour or smell can lead to degradation in water
quality and thus, risk to human health if consumed. Although there are separate
national limits for TOC in Australia and Indonesia, there are no international TOC
quality guidelines due to dependence on location and social tolerance (Borovac
2009).
In a study conducted in Yogyakarta in 2014, seven sites were tested for presence of
TOC – only two were found to contain high amounts of the material (Sensamras,
Hendraya and Putra 2014). These were due to an isolated incident where there was
substantial oil disposal and leakage from underground fuel tanks in 1998
(Sensamras, Hendraya and Putra 2014). As shown in Figure 11, the highest amount
of contamination was centred largely at the site where the incident occurred i.e. near
the railway station. However, as can be seen in the same figure, the entire plume
itself covers a large area. The average distance of the contamination zone ranges
from 150-200 metres (D. Putra, The Impact of Urbanization on Groundwater Quality
2007).
32
The impact of contamination caused by industrialization is supported by Table 4,
detailing industrial zones which display highest TOC contamination.
Figure 11 - Model of TOC Contamination in Yogyakarta
City (Sensamras, Hendraya and Putra 2014)
Table 4 - Risk Matrix of Organic Contaminaton in Yogyakarta (D. Putra, The
Impact of Urbanization on Groundwater Quality 2007)
33
Similarly, in Perth, two incidences of high contamination were noted, one of which
was in 1989, where 500 litres of gasoline were released into groundwater from
underground gasoline tanks, causing BTEX contamination (Prommer, Barry and
Davis 1998). Also, an incident in 1992 resulted in a study being carried out, which
uncovered severe contamination of trichloroethylene, with a concentration of 2000
micrograms/litre being detected in groundwater (Benker, et al. 1994). This was due
to several industrial areas that had failed to ensure that their waste effluent did not
affect groundwater, most especially with residential areas being so close in proximity
to these areas, located in Jolimont. Analysis found that the plume covered a distance
of 900 metres (Benker, et al. 1994).
Generally speaking though, the above incidents have been singular in nature due to
ill fortune or the failure of industrial organizations to form stringent safety plans. In
recent years, there has been no significant industrial discharge of organic pollutants
into groundwater in either Yogyakarta or Perth.
3.8.2 Nitrogen
The reduction of nitrous compounds in water is vital in assuring good water quality.
To understand the presence of these compounds, one must understand the global
nitrogen cycle. High ammonia levels are usually from agricultural fertilizers,
pesticides, domestic waste and sewerage effluent. The transformation of this into the
transient compound nitrite via Nitrosomonas bacteria is the pre-step to forming
nitrate (Spalding and Exner 1993). The concentration of these compounds in
Australia, Indonesia and the World Health Organization (WHO) guidelines are
expressed in Table 5.
Table 5 - Comparison of Nitrogen Guidelines in Indonesia, Australia and the World
Compounds/Ions World Health Organization (WHO) Guidelines (mg/L) (World Health Organization 2017)
Australian Drinking Water Guidelines (ADWG) (mg/L) (National Health and Medical Research Council 2011)
Kementrian Kesehatan (Ministry of Health) – Indonesia (mg/L) (Menteri Kesehatan Republik Indonesia 2010)
Ammonia Not Specified Not Specified 0.5 mg/L (aesthetic)
Not Specified
Nitrate 50 50 (infants) 100 (adults)
50
Nitrite 3 3 1
Due to rapid urbanization, industrialization and population growth, usability of
groundwater has decreased due to high nitrogen contamination (Smith, et al. 1999).
34
This is supported by a study where 123 wells in the Kotagede district alone were
sampled. Results showed that at least half of these exceeded WHO guidelines for
safe nitrate levels in groundwater (Smith, et al. 1999). High levels of nitrate
contamination are largely influenced by increasing population density, as shown by
Figure 12 (D. Putra, Estimation, Reality and Trend of Nitrate Concentration Under
Unsewered Area of Yogyakarta City - Indonesia 2010).
There is evidence of nitrogen contamination in Perth, largely contributed by
increased urbanization. However, there are also suggestions of denitrification taking
place due to the presence of organics – overall nitrogen contamination may be lower
in certain locations because of this e.g. Bassendean (Dillon, et al. 1999). The key
sources of nitrogen in Perth are similar to other setting around the globe, as are
fertilizers & pesticides for lawn maintenance and septic tanks (Sarukkalige and
Ranjan 2011). These sources will increase as population grows, due to an increase
in demand (Dillon, et al. 1999). As such, nitrogen contamination will continue to
increase.
3.8.3 Acidification & Heavy Metals
Excessive excavation and dewatering in Perth has led to disruption of naturally
occurring sulfidic peat soils (Wong, et al. 2004). Oxidation of this material has
caused extensive acidification and heavy metal contamination. High levels of arsenic
(7 mg/L), aluminium (290 mg/L) and iron (1300 mg/L) have also been noted, along
with a pH of 1.9 (Sarukkalige and Ranjan 2011) (Wong, et al. 2004). The
Figure 12 - Correlation of Population Density with Nitrogen
Contamination in Yogyakarta (D. P. Putra 2011)
35
composition of this groundwater, when used on gardens, was observed to have
caused plant death. Acidic groundwater currently reaches to a depth of 5-10 metres,
implying that it has not yet affected deeper groundwater reserves (Wong, et al.
2004). However, as sulfidic peat soils are common in the Perth area, it is important
to take preventative measures to ensure that it does not severely mix with
groundwater and become a continuing issue.
No sources were found pertaining to acidification in Yogyakarta. However, heavy
metals have been observed in certain areas, most particularly in industrial zones.
Piyungan landfill in the Bantul region receives solid waste from Bantul, Sleman and
Yogyakarta city. The high metallic levels in leachate produce a high risk to
groundwater streams (Marwati 2012). Minerals such as iron and manganese have
regularly been recorded in excess of normal standards (Marwati 2012). Also, a study
conducted in 2010 found that there are also amounts of cadmium, chromium, copper
and zinc in excess of World Health Organization (WHO) guidelines, implying that the
water is unsafe (Pich, et al. 2010).
3.8.4 Salinity
In the Samas and Bantul regions of Yogyakarta, a study found that the province has
not yet experienced saltwater intrusion to a great extent. However, laboratory results
found that electrical conductivity ranged from 216-856 μS/cm and Cl & Cl- ion
concentrations ranged from 11-72.6 mg/L.
Around the city of Perth itself, there is a relatively low risk of salinity as compared to
other parts of state. This is because, due to excessive deforestation and salinity in
the early 1900s, a strategy was developed where reforestation was encouraged to
replenish the Mundaring reservoir (Bennett and Macpherson 1983). However, in
agricultural areas across south-western Australia, excessive clearing of native
vegetation has introduced extensive salinity into groundwater aquifers (McFarlane,
George and Nulsen, Salinity Threatens the Viability of Agriculture ad Ecosystems in
Western Australia 1997). Groundwater levels in these areas have generally risen by
more than 30 metres, leading to the creation of saline aquifers where there were
none before (McFarlane, George and Nulsen, Salinity Threatens the Viability of
Agriculture ad Ecosystems in Western Australia 1997). This puts increasing pressure
on the catchments where there is reduced salinity to provide water for all residents.
3.8.5 Pathogens
The inability to contain domestic wastewater makes groundwater a rampant source
of bacterial contamination in Yogyakarta. From a study of 145 onsite wells, roughly
82.8% had total coliform greater than 50 MPN/100 mL (Kamalyan n.d.). Research
also estimates that the average distance from septic tank to well ranges from four to
eight metres – well below the recommended ten metres (Kamalyan n.d.). Figure 13
shows a comparison of coliform levels in 1999 and 2000 in areas with high
population density.
36
Although, there are records of bacterial contamination, including fecal coliforms, in
Perth, the problem is not extensive since the city has a well-supplied sewer network
(Appleyard 1995).
3.9 Public Awareness
From the research above, it can be seen that Yogyakarta has a major groundwater
issue – a combination of decreasing aquifer quantity and quality make it a hazard to
residents currently using it regularly. However, much of it stems from a lack of
awareness and public participation to effectively clean up these contaminated waters
(Santikayasa and Perdinan 2016). A groundwater sustainability infrastructure index
was developed and applied to five areas that were deemed to have the most impact
on change:
Groundwater monitoring
Knowledge, generation and dissemination
Regulatory intervention
Public participation
Institutional responsibility
Figure 13: Coliform Levels in Areas of Yogyakarta from 1999 and 2000
(Kamalyan n.d.)
37
Figure 14 shows a schematic developed to rate how the aforementioned agencies
contribute to groundwater sustainability in Yogyakarta. It was found that while
regulatory intervention has been good, the other four areas are quite poor in
comparison (Santikayasa and Perdinan 2016).
A study was conducted by CSIRO to assess the values that Perth residents have
towards groundwater sustainability and conservation (Tapuswan, Leviston and
Tucker 2009). Using a Sense of Place methodology, it was found that 73% of
residents were aware of the current groundwater situation, most especially relating to
the Gnangara Groundwater System. Residents were largely interested not only in
groundwater conservation for their own use, but also in increasing the aesthetic
values of the locations they lived in (Tapuswan, Leviston and Tucker 2009). As
addressed in the section Policy and Regulation, Perth has a consistent record of
monitoring groundwater and applying relevant legislation to ensure standard targets
are met.
3.10 Remediation Methods
From the sections listed above, it is clear to see that both Yogyakarta and Perth
have a groundwater contamination issue. As the field study has been conducted in
Yogyakarta, treatment methods will be trialed on the groundwater from Indonesia.
The treatment methods discussed below were found to be the three most common
types of groundwater treatment and were chosen for this literature review based on
their ability to remove the aforementioned contaminants.
Figure 14: Groundwater Sustainability Infrastructure Index (Santikayasa and
Perdinan 2016)
38
3.10.1 Granular Activated Carbon
The use of carbon filtration for treatment of contaminated waters has been
widespread for many years. The main advantage of using granular activated carbon
are the adsorption properties that it contains and the pore sizes which allow for faster
flow through the system (Borovac 2009) – Figure 15 shows this in a schematic
manner. Figure 6 also shows how carbon filters are commonly used in household
appliances to eliminate contaminants.
A study in China found that the use of granular activated carbon (GAC) achieved
93% ammonia nitrogen removal (Chung, Lin and Tseng 2005). However, several
other sources have a low removal rate of total dissolved nitrogen, with approximately
43% being removed. Therefore, for use of this type of treatment method, it would be
best to identify which types of nitrogen are present in the groundwater stream. As
noted above, much of the nitrogen in Yogyakarta is associated with high population
and domestic waste, which is high in ammonia. Therefore, the GAC method could be
used to effectively remove nitrogen present. It was also noted that GAC is
particularly useful in the removal of heavy metals, with a removal efficiency of
approximately 90% (Wilkins and Yang 1996). GAC was also found to have removed
80% turbidity (Hatt, Germain and Judd 2013) and 80-90% removal of total dissolved
organics (Dosoretz 2008).
3.10.2 Biosand Filtration
The understanding that household treatment systems are largely capable of treating
a variety of contaminants in water has led to the selection of a biosand filter as a
potential technology for groundwater remediation (Borovac 2009). The components
of this system are identified in Figure 16.
Figure 15 - Household Application for Activated Carbon Filters
(Borovac 2009)
39
A study in Haiti found that an output flow rate of more than 36 litres/hour would
decrease treatment of water; however, it was found that 36 litres/hour is sufficient to
providing water for an average of 18 people (Lentz 2007). Hydraulic loading rate did
not seem to have significant differences in the removal of contaminants (Kennedy, et
al. 2012).
A study in South Africa in 2012 found that using standard biosand filters removed 99
to 100% of total coliform bacteria and had a turbidity ranging from 0.6 to 0.8 NTU
(Mwabi, Mamba and Momba 2012). Due to high effectiveness in contaminant
removal, this technology has been introduced to several developing communities.
Biosand filters are also useful in the removal of several heavy metals – a study in
China (Tang, et al. 2010) on river water found that:
74.75% of iron (Fe) was removed.
76.55% of manganese (Mn) was removed.
74.07% of lead (Pb) was removed.
68.82% of chromium was removed.
3.10.3 Reverse Osmosis
Reverse osmosis has been widely used to treat a range of different water sources
including seawater, wastewater and groundwater. Although reverse osmosis has
been shown to remove pathogenic presence in contaminated waters, this is not
recommended for long term use (Durham and Walton 1999). Issues such as fouling
and leakage through the semi-permeable membrane can affect the efficiency of
removal (Durham and Walton 1999). A study in Belgium found that instead of directly
using the raw water as the feed for reverse osmosis, using microfiltration as a pre-
treatment step eliminated all coliform (Van Houtte, et al. 1998). However, the small
Figure 16 - Schematic of Biosand Filter (Borovac 2009)
40
membrane size is suitable to remove all other contaminants. A study in Pretoria
found that reverse osmosis is well suited to nitrogen removal, with removal rates
ranging from 85-95% on average (Schoeman and Steyn 2003)This was supported
by a trial study conducted in Norway, which recorded a removal efficiency of 95%
(Bilstad 1995). However, it should be noted that pre-treatment using cartridges
should form an essential step in the reverse osmosis process in order to remove any
sediments that may clog the membrane.
3.10.4 Chlorine Disinfection
In order to remove bacteria from water bodies, chlorination has repeatedly been
proven to be the most effective way of achieving this. It is particularly effective in
removing fecal coliforms such as E. coli. This could most especially be used in
Yogyakarta as many of the bores and wells are open, and oxidation has caused
bacterial populations to grow. However, how much of the chemical being used must
be carefully monitored, as high quantities of chlorine can severely reduce pH, which
is detrimental in the eradication of bacteria (Alberta Agriculture and Forestry 2018).
3.11 Conclusion
The identification and comparison of these issues has shown that while Yogyakarta
and Perth are facing different levels of water stress, they share many problems such
as rising population demand, excessive usage of groundwater and high
contamination. They also share various physical attributes implying that recharge
and remediation solutions would be similar in both locations.
In terms of assessing groundwater recharge, it is clear that both cities suffer from a
lack of natural recharge from precipitation events, as indicated by Section 3.1. Land
development, including excavation works has prohibited the reception of rainwater to
the aquifers. Low permeability soils in Yogyakarta act as aquitards and further
disrupt natural recharge. However, unlike Perth, a point of concern in Yogyakarta is
also excessive urban recharge to groundwater reserves. Several contaminants have
been identified in both cities, although the types of constituents vary. In Yogyakarta,
research has identified that hydrocarbons, heavy metals, nitrogen and coliform are
all present in varying amount. This has caused severe groundwater deterioration to
the extent where human health is now a large concern.
While there are gaps in regulatory enforcement and public awareness and
participation, the main problems of groundwater management in Yogyakarta lie in an
inability to produce an effective groundwater recharge and remediation strategy.
Using principles that have been applied in Perth and beyond, this study will aim to
create a sustainable framework that aims to replenish groundwater reserves and
clean up contaminated aquifers.
41
4 Methods
In pursuit of information on artificial aquifer recharge, groundwater pollution
treatment and governmental and behavioural obstacles, there were three separate
areas that required different approaches. These are listed below.
Water depth and hydraulic conductivity to aid in locating a feasible site for
artificial aquifer recharge schemes.
Social surveying of local residents to understand current concerns
surrounding groundwater, particularly focussing on chemical contamination,
public acceptance and the presence of different socio-economic classes in
Yogyakarta.
Water contamination and sampling to determine superficial water chemistry
and chemical compounds present in the groundwater.
Locations were predetermined based on their ability to include all five regencies the
sampling regime and also on their frequency of use by local residents. The majority
of locations were concentrated within or near the urban centre and the regency of
Sleman, as this is where most of the urban population dwells and groundwater
extraction is at its peak. However, southern and western regions (i.e. Bantul and
Kulon Progo) were included in the study to assess the impact of groundwater
recharge and pollution in coastal areas.
Groundwater extraction sites were usually private and/or PDAM (Perusahaan
Daerah Air Minum – private Indonesian water company) connected – others were
public wells. Figure 17 shows the different location across the province – eighteen in
total were sampled for this dissertation.
Figure 17 – Locations
Visited and Monitored
42
4.1 Water Depth and Hydraulic Conductivity
The determination of water depth and hydraulic conductivity was done following the
procedure in Appendix 4A.
4.1.1 Permeameter
The permeameter used was modelled after the Talsma-Hallem method of measuring
Ksat. Using an auger to dig a shallow hole, the soils then wetted with water – this is a
limitation as it will only indicate Ksat of the surface, and will not show any changes as
soil geology changes with depth. The permeameter is then placed on top of this
area. Water will rise back up the instrument via the inner tube. This method works by
maintaining a constant head pressure i.e. the water level in the ground.
4.1.2 Computer Modelling
There were several software packages involved in producing images to aid in the
determination suitable sites for recharge. GIS packages such as ArcGIS and Terrset
were used to pinpoint certain locations around the area, in terms of hydraulic head
and Ksat. ArcGIS proved a useful tool in assessing land use, due to the installed
database and geological base maps. The images will be shown in the Chapter 5.
It was recommended that a basic geochemical model be used to show the mixing
between rainwater and groundwater streams. This was to verify whether water
quality will increase/decrease using artificial recharge. A geochemical modelling
package called Phreeqc was used to determine pH, optimal temperature and
chemical constituents present after mixing. The results from this will be shown in
Chapter 5.
Figure 18 – Permeameter
43
4.2 Water Contamination
There were two main aspects in the gathering of information on water contamination:
a qualitative social survey and chemical analysis conducted on groundwater samples
from each site. These are explained in the following sub-sections
4.2.1 Social Surveying
This approach was mostly used to gain an understanding of residents’ perspectives
on groundwater quality in their locality, issues that were currently being faced and
how they were handling these problems. The survey was used to determine thoughts
on public acceptance of remediation techniques, local views on government
assistance and socio-economics of households. Eighteen households were travelled
to, and the questionnaire was performed verbally with the assistance of colleagues
for translation. A rapport was struck with locals and the author was able to converse
with them amiably to understand their concerns, which formed a basis of what
constituted behavioural barriers of new techniques in the process.
While it would have been preferred for only one person to answer the questionnaire,
entire families often came out to greet the author, ranging from two to three people in
each home. This made it difficult to quantify the number of participants in the social
survey, although it is estimated to be between fifty and sixty people.
A template was formed asking varied questions relating to groundwater in
Yogyakarta, as shown in Table 6.
Location of Groundwater Wells e.g. Grand Permata Residence
Questions Answers
How important is groundwater in completing household and/or business activities?
Not Important; Slightly Important; Important; Very Important.
Do you use groundwater for all domestic purposes? If not, which water resource do you rely on?
Yes; No. What do you use instead of groundwater? (If Applicable)
Do you find that groundwater extracted from private/public wells is safe to use and drink?
Not Safe; Slightly Safe; Safe; Very Safe.
Do you have to treat the water prior to using it, and if so, how?
Yes; No. How do you treat the water? (If Applicable)
Do you feel that you receive enough water to carry out all household activities?
Yes; No.
Do you feel that authorities Yes; No.
44
fairly allocate water resource around the province?
Are you aware of educational campaigns or efforts from government to improve the groundwater situation in Yogyakarta? How much of an impact do they have on how you use water?
Yes; No. Not at All; Slightly Relevant; Relevant; Important; Very Important.
How do you feel the issue of groundwater depletion and pollution can be solved?
No pre-selected answer to this question – dependent on individual’s own views.
What are your biggest concerns for groundwater use in Yogyakarta in the future?
No pre-selected answer to this question – dependent on individual’s own views.
Table 6 – Template of Questionnaire Asked of Local Residents
4.2.3 Sampling
Groundwater samples were analysed in terms of chemical composition. The
procedure for this is explained in Appendix 4B.
4.2.4 Experimental Design
The design of pilot scale remediation techniques were limited due to the loss of
samples during transportation from Yogyakarta to Perth (explained in Chapter 1). As
such, experimental design for the biosand filter, activated carbon filter, reverse
osmosis unity and chlorination setup developed for this study could not be trialled.
However, in lieu of this, qualitative assessments were carried out on the
aforementioned technologies according to key stakeholder values identified for this
project. They are as listed below:
Removal efficiency – the ability of the remediation technologies to perform
adequately in the removal of contaminants.
Cost – the price of implementing said technologies.
Ease of operation – the ability of users to use the selected techniques with
relative ease.
Maintenance – whether the equipment will require constant care or is largely
self-sufficient in this manner.
Government approval – should any of the aforementioned techniques require
government assistance in installing technologies into homes.
Public approval – whether the public would be open to implementation of
remediation techniques in their homes.
45
5 Results
This section will display the results that were produced over the course of this thesis.
There were four different types of results:
GIS imaging of water depth and hydraulic conductivity.
Geochemical modelling to determine molality of chemical constituents and
their distribution in the mixed groundwater and rainwater stream.
Social surveying to understand public reactions to groundwater pollution and
possible implementation of remediation techniques.
Groundwater sampling to determine concentrations of contaminants in
groundwater samples.
The aforementioned areas will be explained in this chapter.
5.1 Water Depth and Hydraulic Conductivity
Figure 19 above shows the different locations that were travelled to in Yogyakarta
and their corresponding depths. Site locations are represented by the purple points
on the map. Using ArcGIS, a raster interpolation was done to gain an understanding
of water depth for the entire study area, despite not having more location sample
points. In future, more sample points should be taken to verify Figure 18, most
especially in the blue regions of the map where there are less values. Areas with
deep groundwater depth are shown in warmer tones (i.e. yellow, orange and red),
ranging from 9.31-18 metres. Conversely, areas in cooler tones (i.e. blue and green)
have much higher hydraulic heads, showing that low water depth is concentrated in
the north-east of the study area.
Figure 19 – Map of Groundwater Depth (m)
Depth of
Groundwater
(m)
46
Figure 20 is a representation of hydraulic conductivity within the study area. Similar
to the previous map of water depth, the raster interpolation tool from ArcGIS
provided image analysis for the whole study area, allowing generalizations to be
made. Raster interpolation predicts values for cells where there are no discrete
numerical entries. Warmer colours are indicative of high hydraulic conductivity zones
while cooler tones are for lower hydraulic conductivity zones, as represented by the
scale to the right of Figure 19. From the image, it can be seen that hydraulic
conductivity increased to the eastern end of the study area where warmer tones are
prevalent, and so there is greater confidence in this portion of the study area.
Figure 20 – Hydraulic Conductivity (m/day) in Yogyakarta
Hydraulic
Conductivity
(m/day)
47
Figure 21 once again shows hydraulic conductivity, but the author has distinguished
particular points on the map. A table of depth measurements (refer to Appendix 1)
yielded an average water depth of 7.67 m. Any locations 20% outside of this range
(i.e. 9.2 m) are shown by the green placemarks situated on the map. In looking at the
agglomeration of values, it is clear that the north/north-eastern parts of the study
area have the lowest water depth. Further analysis on what this implied for recharge
site selection will be discussed in Chapter 6.
5.2 Geochemical Modelling
The modelling software Phreeqc was used to mix both rainwater and groundwater to
determine final water quality. Parameters were based on constituents present in the
in rainwater and groundwater. Rainfall measurements were not personally recorded
for this study and thus, could not be analysed. However, an article on rainwater
analysis in Yogyakarta (refer to Appendix 1) was discovered and this was used as a
substitute to act as Solution 1. Solution 2 consisted of the chemical concentrations
from the groundwater samples at site locations 1-4, as listed in Table 7. The ions
indicated in the table are those present after mixing and transformation of initial
species occur. Further discussion will occur in Chapter 6.
Table 7 – Distribution of Species in Groundwater Wells
Molality (mol/L)
Parameters (Ions in Mixed Stream)
Bapak Muji Intan 50 House
Ibu Najib Ibu Suwardi
Average
H+ 1.158E-07 0.000000198 1.142E-07 1.709E-07 1.49725E-
Figure 21 – Identification of Locations with Lowest Water Depths against
Hydraulic Conductivity
Hydraulic
Conductivity
(m/day)
48
07
OH- 1.041E-07 5.694E-08 9.89E-08 8.187E-08 8.54525E-08
H20 55.51 55.51 55.51 55.51 55.51
Cl- 0.001481 0.0003766 0.0004203 0.0002101 0.000622
MnCl+ 8.216E-08 6.539E-10 5.818E-10 2.223E-10 2.09045E-08
MnCl2 8.216E-12 1.041E-13 1.032E-13 1.989E-14 2.1108E-12
MnCl3- 3.351E-15 1.079E-17 1.194E-17 1.151E-18 8.4372E-16
H2 0 0 0 0 0
Mn2+ 0.000002534
4.544E-07 3.634E-07 2.728E-07 9.0615E-07
MnOH+ 5.976E-10 6.197E-11 8.58E-11 5.523E-11 2.0015E-10
Mn(NO3)2 7.745E-16 1.276E-16 7.559E-17 2.022E-16 2.94973E-16
Mn(OH)3- 2.585E+20 9.277E-22 3.867E-21 8.665E-22 6.4625E+19
Mn3+ 1.748E-19 5.529E-20 2.315E-20 2.677E-20 7.00025E-20
N2 3.77E-10 4.857E-10 3.257E-10 6.633E-10 4.62925E-10
NO2- 1.298E-15 9.8E-16 1.033E-15 2.007E-15 1.3295E-15
NO3- 0.000009628
0.000008821 0.000007612
0.00001422
1.00703E-05
O2 1.885E-09 1.214E-09 8.143E-10 1.658E-09 1.39283E-09
5.3 Social Survey
Table 8 – Social Survey of Residents on Groundwater Contamination Issues
Location of Groundwater Wells e.g. Grand Permata Residence
Questions Answers
How important is groundwater in completing household and/or business activities?
All people said that groundwater is very important to them as it forms majority of their water capacity, if not all.
Do you use groundwater for all domestic purposes? If not, which water resource do you rely on?
All replied they use groundwater for all domestic purposes.
Do you find that groundwater extracted from private/public wells is safe to use and drink?
People from lower socio-economic classes said that the water ranged from slightly safe to safe. Those from more affluent localities said groundwater from wells is very unsafe.
Do you have to treat the water prior to using it, and if so, how?
Most people treat groundwater prior to use, by boiling the water to get rid of bacteria.
49
Do you feel that you receive enough water to carry out all household activities?
Those within city limits with wells said that water levels had constantly decreased. Those with access to PDAM pipework and areas where water depth still high said there is enough water, however because it is contaminated, there is only so much that the homeowners think is safe for drinking, showering and cooking.
Do you feel that authorities fairly allocate water resources around the province[6]?
People from lower socio-economic classes feel that PDAM restricts access of water pipework to city limits and expenses are high. As such, they are required to extract water from wells.
Are you aware of educational campaigns or efforts from government to improve the groundwater situation in Yogyakarta? How much of an impact do they have on how you use water?
Most people are aware of the groundwater problem in Yogyakarta. Only have slight impact on use of groundwater as no concrete investigation or solution has been proposed in the past.
How do you feel the issue of groundwater depletion and pollution can be solved?
Using rainfall to fill up the aquifers again. It would be nice to have access to cleaner water for drinking and cooking.
What are your biggest concerns for groundwater use in Yogyakarta in the future?
Not enough water in the future; lower socio-economic classes replied that they feel clean water will be restricted only to city limits.
5.4 Groundwater Sampling
Manganese, while not a high concern, was tested due to mention in the literature
review (Section 3.8.3). Remaining constituents were also based on concern
addressed in the literature review, 3.8.
EC TDS Temperature Total Alkalinity Cl NO3 Mn Fecal Coli
X Y μs/cm mg/L °C ppm CaCO3 mg/L mg/L mg/L mpn/100 mL
1 Bapak Muji -7.9161369 110.3926652 6.9 974 487 28 460 105 1.02 0.28 ≥400
2 InTan 50 House -7.772103 110.325253 6.5 294 164 27 120 26.7 0.92 0.05 ≥400
3 Ibu Najib -7.7680252 110.4041404 6.9 286 143 27 120 29.8 0.77 0.04 ≥400
4 Ibu Suwardi -7.825752 110.397876 6.6 318 159 33 200 14.9 1.59 0.03 ≥400
Average 6.725 468 238.25 28.75 225 44.1 1.075 0.1
pH
Parmeters Measured
Site No. Location
Coordinate
Table 9 – Chemical Constituents
50
6 Discussion
6.1 Artificial Aquifer Recharge
To determine whether artificial aquifer recharge is a feasible option in Yogyakarta
province, two different parameters were considered. They were:
1. Site suitability for proposed recharge location(s).
2. Suitability of stormwater addition to groundwater.
Based on whether the aforementioned were deemed suitable or not, a strategy to
implement artificial aquifer recharge was proposed. In particular, there was a focus
on the general merit of unconfined aquifer recharge as compared to confined aquifer
recharge and which design would be best for replenishing aquifers in the region.
6.1.1 Site Suitability for Proposed Recharge Location(s)
In evaluating whether artificial aquifer recharge was suitable for replenishing
Yogyakarta’s aquifers, variables such as slope, land cover, water depth and
hydraulic conductivity were assessed. Contour maps and GIS images were created
for the variables (refer to Chapter 5) and then studied to determine the best locations
for proposed artificial aquifer recharge. A soil geological GIS image was not created
because surface geology in Yogyakarta is consistently of a sandy loam quality.
Areas where groundwater depth is critical were concentrated in the northern section
of Map 5 (refer to Chapter 4). However, due to the north-to-south trajectory of
groundwater in the region, which is supported by Map 3 (Chapter 2) and literature
review (Chapter 3), aquifer recharge in this location implied that the water table
would mostly increase in areas south of the target zones, providing no relief to these
locations despite their proximity to the recharge site. It was therefore proposed that
aquifer recharge lie further north, slightly outside the bounds of the study area. This
was based on two reasons:
1. By placing the recharge location further north of the study area, it will ensure
that the groundwater table increases in all regions as groundwater moves in a
north-to-south direction.
2. The placement of location in less populated areas outside the urban city
would decrease chances of any urban obstruction e.g. walking on the
infiltration zone.
From Figures 20 and 21 showing hydraulic conductivity zones (Chapter 5), it was
observed that the main areas where groundwater depth is perceived severe are in
opposing zones – one has a much higher hydraulic conductivity as compared to the
other. Placement of aquifer design is based on hydraulic conductivity – a passive
infiltration basin would favour the north-eastern region of Yogyakarta, where
hydraulic conductivity is high. To compare the effect this would have on infiltration,
Table 10 and Figure 21 were produced using the following equation:
51
Qi = A x Ksat
Where Qi = infiltration rate (m3/s) A = area of infiltration (m2) Ksat = saturated hydraulic conductivity (m/s) Table 10 – Effect of Different Hydraulic Conductivities on Infiltration Rate
Hydraulic Conductivity Q for Infiltration Basin in Sandy Loam Soils (m3/s)
Medium Conductivity (5.160 m/day)
1.1574
High Conductivity (8.64 m/day)
1.9907
Placing the sites in a location with higher hydraulic conductivity, this improves
infiltration by almost 42%. As such, instead of focusing on the northern boundary of
the city for capture, the target area became narrowed to the north-eastern edges of
the city for maximum recharge of groundwater. A four-kilometre buffer zone was also
Figure 22 – Infiltration Rate VS Hydraulic Conductivity
(3)
Infiltration Rate (Q) of Aquifer Basins
at Varying Conductivities
Medium Conductivity
(5.160 m/day)
52
applied around the sites so the recharge zone would be located outside of
Yogyakarta city – this was determined by estimating radial distance to outside of the
city centre in the northern areas. This was to ensure that urban obstruction to the
recharge zone, and in turn any disruption caused by the development, would be
minimal. Figure 23 depicts the boundary where recharge location was proposed.
The orange boundary on the north-eastern corner was the proposed area for artificial
recharge. The blue circles are indicative of four-kilometre buffer zones created
around location sites.
6.1.2 Site Suitability of Stormwater Addition
As per Section 5.2, Geochemical models were created to predict whether chemical
composition of rainfall, when combined with groundwater, would result in the
formation and/or transformation of compounds that would further deteriorate present
aquifer conditions.
There was no significant change in pH, which stayed within the range of 6.5-7.0,
which is within WHO recommended limits. The two highest constituents, as per
Table 7, were found to be Cl- ions and water with limited concentration of the
remaining contaminants. This supports the initial laboratory result where chloride
Figure 23 – Buffer Zones and Proposed
Placement of Recharge
Proposed Recharge Site
53
was of greatest concern, with nitrate and manganese being nearly negligible in
geochemical calculations. It should be noted that the application Phreeqc did not
allow E. coli and total dissolved solids to be inputted as measures. This could be a
reason why calculated percentage error of chemical composition is exceedingly high
– in the high 80s. Due to restrictions in the analysis of the samples, potential
compounds that may exist in the groundwater were not identified. For the purposes
of this study, however, it is clear that the chemical contaminants identified in this
study, with the exception of Cl- were not of concern.
Precipitates were also an output of the modelling. The generated two precipitates
present in the mixed stream – manganite and pyrolusite.
Low toxicity of contaminants identified in Table 7 indicated that mixing of rainwater
and groundwater form recharge purposed would not result in water quality
deterioration.
6.1.3 Recharge Options
In designing a recharge option, two different types of aquifer recharge were analysed
– unconfined aquifer recharge and confined aquifer recharge (refer to Chapter 3 for
further information). There was a proposed design for each option as shown by
Figures 24 and 25 below.
Figure 24 - Schematic of Infiltration Basin
54
Two hectares is the minimum recommended area of infiltration basin (Regional
Water Resource Agency n.d.). For this reason, the proposed infiltration basin area in
Diagram 4 was chosen. Depth of the infiltration basin was determined using (4)
(Regional Water Resource Agency n.d.):
d = fd x tmax
d = Depth of infiltration basin (m)
fd = Design Infiltration Rate (m/hr)
tmax = detention time (hr)
The following are full metric calculations using the above equation.
Soil Infiltration Rate (f) = 33m/hr
Design Infiltration Rate (fd) = 0.5 x f = 16.5 mm/hr = 0.0165 m/hr
Depth of Infiltration Basin (d) = 0.0165 m/hr x tmax (48 hours (Regional Water
Resource Agency n.d.)) = 0.792 m (2.598452 feet)
Assuming 2 hectares as minimum area (Regional Water Resource Agency n.d.),
volume V = 0.792m x 20,000 m2 = 15840 m3 storage capacity.
Stormwater and rainwater will act as inputs, with the only output being through the
basin itself, via the porous media, into the groundwater. Alternatively, in Figure 24,
rainwater is received into an above-ground surface water tank. As per the diagram,
the tank will preferably be at a higher gradient to the bore to encourage stormwater
collection and movement – the province of Yogyakarta is on a slope so a suitable
location north of the injection well can be found. From there, the gradient will allow
the water to flow to a bore where it is pumped into aquifer below. There are merits to
both systems, as discussed in Table 11 below.
Table 11 – Comparison of Infiltration Basins versus Injection Wells
Figure 25 - Schematic of Proposed Water Detention and Injection
Well
(4)
55
Factors to Consider Infiltration Basins Injection Wells
Capital Cost (i.e. Construction and Equipment)
$8333/acre = $16666 for 6-hectare basin (Taylor 2005)
$27130 including bore digging, storage tank pump cost and installation, gravel tube and grout seal (refer to Appendix 3 for breakdown of price).
Maintenance Self-maintenance - clogging caused by suspended matter and silts.
Clogging - lack of education on operation can lead to misidentification of issues and cause the system to become obsolete.
Effectiveness in Recharging Aquifers
Slow, dependent on stormwater inflow and precipitation.
Good, bypasses soil/rock formations underground for direction injection.
Rate of Recharge Slow Fast Placement Public open space Open space for placement
of tank and bore.
Infiltration basins were found to be the preferred option; firstly due to the high volume
of water they are capable of holding. Although infiltration rate is slower as compared
to injection wells, lower capital cost and low self-maintenance favour this method. It
also allows for suitable stormwater diversion and management to allow for the
development of a suitable strategy in this area, which Yogyakarta and wider
Indonesia lack.
6.1.4 Contrast to Perth and Wider Australia
Stormwater recharge strategies are currently being used in Perth, such as the
Hartfield Park Development in Kalamunda. This development extracts stormwater
from the Woodlupine Main Drain during winter, which injected a recorded 4,400
kilolitres in 2016 [38]. The use of this to replenish aquifers for future use by Perth’s
residents is an acute similarity also being faced in Yogyakarta – the welfare and
future water security of the people must be preserved. However, a lack of
infrastructure in Yogyakarta means that a similar system cannot be employed, and
passive techniques must be relied on to replenish the aquifers.
Similar climate and geological conditions prove that though the system may be
theoretically feasible in Yogyakarta, it is not a practical option due to lack of
infrastructure and appropriate regulatory framework. Permission and support from
the government must be received before such a project is undertaken. In Perth,
Water Corporation is fully in support of groundwater replenishment, with the aptly
named Groundwater Replenishment Scheme in Beenyup [39] restoring the aquifers
with highly treated wastewater. The government in Yogyakarta must have the same
driving encouragement to facilitate the implementation of the proposed aquifer
recharge strategy. Its potential success could also be a path to forming more
56
stormwater management policies in cities across Indonesia, particularly in areas
such as Yogyakarta where flash flooding can occur.
6.2 Remediation Techniques
The presence of contaminants in groundwater is a big public health hazard. To
assess which remediation techniques are best suited, a social survey was carried
out to understand the needs of the residents and a qualitative assessment of
treatment technologies. As mentioned in the Introduction (refer to Chapter 1), the
unavailability of groundwater samples in Australia limited the author’s ability to
conduct a technical assessment on removal efficiencies. As such, it should be noted
that all removal efficiencies for corresponding techniques are from several literature
sources.
6.2.1 Social Survey
Studying the generalized results in Table 8 (refer to Chapter 5) from the social
survey, majority of people replied that groundwater proved an essential source to
carry out domestic duties. Members of eighteen households commented that they
use groundwater for all chores, but that they needed to boil the water to eliminate
any pathogens. This method however, does not remove other chemical
contaminants such as Cl- ions, which as per Table 9 is a large concern.
Of particular interest are the discrepancies in perceived safety levels of groundwater
depending on socio-economic status. Those from provincial neighbourhoods and low
socio-economic class claimed groundwater is still safe. This is in stark comparison to
those from more affluent localities with more stable jobs, who claimed that
groundwater, most especially from public wells, is very unsafe. The difference in
opinion could be attributed to necessity – one woman claimed “We do not have
access to piped water and infrastructure, so we rely on what is available. We use it
daily so it is not a bad option.”
The economics of a family contribute to perceptions of how much clean water is
available to them. Residents living within the urban centre of the province claimed
that what they have is not enough water for their use. However, those from poorer
backgrounds living outside the city in the regencies of Bantul and Kulon Progo,
replied that while they had observed a decline in groundwater depth in their private
and public wells, they could sufficiently manage with what they had – again because
they did not have any other choice.
When analysing public receptiveness to future remediation works, residents were
excited and had a good understanding of public campaigns and information, mostly
provided by institutional bodies in the city. Once again, however, the economic
barriers provided a challenge to several homeowners, most particularly in Kulon
Progo and Bantul. “I would not pay for expensive equipment to be installed in my
home – my family does not have enough to buy it. Even if we did, it could be used for
better purposes like schooling and transport,” a man from Bantul had replied when
asked of his openness to implementing a technology such as reverse osmosis.
Those within the city from more affluent areas were slightly more open to the idea,
57
but said they would only consider it “if the government provided support.” This is a
sentiment felt similarly across the entire study area. When the man from Bantul was
asked if he would think about the technology if the government provided economic
help, he replied “Yes.” However, he also said that the government and private water
companies (e.g. PDAM) were either focused on isolated communities or urban
centres, and that it was difficult to gain support from them.
In analysing the social survey, it has become clear that although there is a need and
want for remediation technologies, the difference in socio-economic classes provides
a challenge in actual implementation. Those living in developed localities with stable
incomes say that using a system would have several benefits for their entire home,
but the cost of these systems proves an enormous concept to overcome. This is
even more so for those from less fortunate backgrounds. As such, solutions for
groundwater remediation, at an affordable household scale, were proposed so that
they are applicable to all residents of Yogyakarta province.
6.2.2 Presence of Contaminants in Groundwater
From Table 9 in Chapter 5, the two main causes for concern were the presence of:
1. Chloride ions from salinity intrusion.
2. E. coli from anthropogenic activity.
The E. coli levels expressed in Table 9 all have a value greater than 400 mpn/100mL
(mpn is the most probable number). This is because PDAM had observed E. coli
levels of the aforementioned value. However, historical data analysis showed that,
there is an exceedance of E. coli beyond this limit, in some cases being as high as
1800 mpn/100 mL. For this reason, E. coli could not be quantified in a graph.
However, the concentration of Cl- ions at the various locations was compared to total
dissolved solids. The following graph is a representation of this.
58
The strong correlation coefficient shown on the graph proved that chloride ions
formed 20% of the total TDS concentration. As specified in Section 6.1.2, the
geochemical model showed a particularly high value for chloride ions as compared
to other constituents, further supporting the theory that chloride is present in high
quantities in groundwater. Also, graphs showing the relationship between electrical
conductivity and total dissolved solids are in agreement, as electrical conductivity is
usually a measure of salt (NaCl) in a solution. This is shown by Figures 27 and 28.
Figure 26 – Correlation between Chloride Ions and
Total Dissolved Solids
Figure 27 – Correlation between
EC and TDS in July
59
The 23% decrease in correlation coefficient is due to lowered Cl- and TDS
concentrations in September 2018. This is due to monsoon rains experienced in later
months, diluting the contaminants in groundwater.
From analysis of the results, remediation technologies were proposed with a focus
on removal of Cl- ions and E. coli.
6.2.3 Assessment of Remediation Technologies
From analysis of the results, remediation technologies were proposed with a focus
on removal of Cl- ions and E. coli. They are biosand filtration, activated carbon
filtration, reverse osmosis and chlorination. A comparison of these treatment
techniques was made according to stakeholder values identified in Chapter 4. It
should be noted that all of the aforementioned techniques are being assessed on a
whole household basis.
Table 12 – Comparison of Remediation Technologies
Biosand Filter Activated Carbon Filter
Reverse Osmosis
Chlorination (0.25 mL of 25mg/L conc. (Northern Territory Government 2014)
Removal Efficiency
>90% fecal coliform (Dosoretz 2008) removal
80-90% removal rate; mostly used for organics
>95% removal of chloride (Kneen, Lemley and
99.9% inactivation of E. coli (Mwabi, Mamba and
Figure 28 – Correlation between
EC and TDS in September
60
Distillation (boiling) required for chloride removal (Wiggill 1974)
(Chung, Lin and Tseng 2005).
Wagenet 1995).
Momba 2012)
Capital Cost $68.80 (Centre for Water and Sanitation Technology 2018)
$69 (Tru Water Aust 2018)
$15000 (Moerk Water 2018)
$68.80 (Maze 2018) (100 L tank) + $51.9 (Hy-Clor 2018) (chlorine) = $120.7
Ease of Operation
Requires daily fillings during 2-3 weeks when bio-layer is growing. Slow flow rate and inconvenient for large daily usage. (Centre for Water and Sanitation Technology 2018)
Easy to use – some education of upkeep required.
Basic training of apparatus required.
Basic training of apparatus. Daily dosing will be required.
Maintenance Fairly simple. Requires regular cleaning. Sand may need to be cleaned. (Centre for Water and Sanitation Technology 2018)
Easy to maintain. However, if regular schedule is not kept, system may be inefficient.
Regions without consistent access to power would require solar powered units.
Would require regular monitoring of tank levels and dosing of chlorine.
Government Approval
Accepted as individual household accessory.
Accepted as individual household accessory.
Central government supports, but only in basic, rural areas.
Readily available in the market.
Public Approval
Yes Yes Those in low socio-economic classes worried about monetary fund.
Yes
61
From these results, reverse osmosis was the most efficient in removal of all
contaminants. The system that is being proposed is a whole house system that will
provide purified water for several purposes such as drinking, cooking, cleaning and
washing. However, its pricing proved problematic since, as explained in the social
survey, wealthier people were still unlikely to implement this technology unless they
received assistance from the government. Although the government provides
household reverse osmosis systems, this is only for isolated, rural communities. As
such, a potential subsidy scheme was suggested to encourage homeowners to
install their own reverse osmosis systems.
While this may be a possibility for those from more stable economic situations, it is
improbable for those from lower socio-economic classes. To supplement the reverse
osmosis system for a more suitable technology, the biosand filter was chosen. This
is because of high chloride and fecal coliform removal efficiencies. Even so, this still
leaves a residual amount of pathogens. Therefore, a hybrid system of biosand
filtration and chlorination tank was proposed, as shown in Figure 29 below.
The concept of having two tanks for treatment is so that disinfection can occur in the
first tank and the wholly disinfected water will be available to the household.
However, this is purely optional and left to the homeowner’s discretion. It should be
noted that this will not provide enough water for all domestic chores. Maximum
volume generated per day was 36 litres (Centre for Affordable Water and Sanitation
Technology 2009). The system is only devised for drinking water and a portion of
cooking water, to eliminate direct hazards to public health. This process essentially
imitates a pool chlorination system, with the exception of the biofilm layer that is
responsible for majority of pathogenic removal in the biosand filter. The main
advantage of this system is that there is no operational cost – it is not dependent on
electricity to produce clean water. However, should this technique be employed,
homeowners would need to be diligent on their tank maintenance, including
purchase of chlorine disinfectant and intermittent washing of sand.
Figure 29 – Schematic of Hybrid
Biosand and Chlorination
Treatment Process
62
7 Conclusion
In conducting this study, the author was able to form an understanding of current
groundwater practices in Yogyakarta. By comparing parameters such as site
description, groundwater recharge and contamination, solutions based on existing
technologies were proposed to aid in the replenishment of groundwater aquifers and
also in remediation of this resource.
In understanding suitability for groundwater recharge, GIS images were created to
understand the terrestrial overlay of the study area and interpolate water depth and
hydraulic conductivity points. This resulted in the understanding that the north-
eastern sector of the study area would be best suited for recharge due to high
hydraulic conductivity and proximity to areas that are most affected by decreasing
groundwater levels. Buffer zones of radius four kilometres were created around the
north-eastern sites to determine optimum site location away from the confines of an
urban setting. Similarly, geochemical modelling on chemical samples was taken to
determine feasibility of addition of rainwater/stormwater to groundwater streams so
that it would not have a negative impact on public health. The results affirmed the
mixing of solutions and so recharge locations are viable.
Recharge technologies were assessed by several values such as their cost, rate of
recharge and maintenance. It was determined that an infiltration basin via
stormwater sump would be the best suited for the area, primarily due to low cost and
high capture without loss of water to absorption by soil. This technology is currently
being applied in Perth on a large scale at Hartfield Park in Kalamunda and the
Andrews’ Farm in South Australia, with both yielding positive results, verifying the
operation of this proposed development.
A social survey of eighteen households was recorded for domestic use, perceptions
of government and public acceptance and future concerns for groundwater concern
they may have. This aided in determining the different socio-economic classes in
Yogyakarta, and ultimately in the selection of relevant technologies. The underlying
concept that was derived was that cost played a major aspect in determining suitable
technologies. To this extent, reverse osmosis systems were proposed for more
affluent localities while a simple biosand filter and chlorination disinfection unit were
proposed for those from low socio-economic backgrounds to provide drinking and
cooking water only.
It was found that while the Indonesian government has funds to allocate reverse
osmosis systems to homes, they are only doing so in isolated, rural communities.
This is in contrast with the literature review, which stated that government regulation
in the province was high. It was suggested that there be a possible formation of a
subsidy scheme to encourage homeowners to invest in reverse osmosis systems.
When looking at the hybrid biosand and chlorination system, it is feasible for
everyone, but is strongly recommended for lower socio-economic classes to invest in
for drinking water as this removes the risk of public health contamination.
63
Recharge and remediation form a key part in managing Yogyakarta’s groundwater
infrastructure. The aforementioned techniques in this section provide a summary of
techniques and strategies that will provide Yogyakarta with a long-term, sustainable
groundwater management plan. The utilization of these methods with adequate
government policy and increased public acceptance will allow for the future security
and longevity in Yogyakarta.
64
8 Recommendations for Further Study
Future works should be considered for this study to verify the proposed placement of
infrastructure. These are explained below.
Artificial Aquifer Recharge and Site Placement
There were several parameters that should be considered for placement of artificial
recharge sites in Yogyakarta Province and provide sufficient recharge of the aquifers
for further use. The recommended parameters that should be noted are explained in
the following points.
1. Trials and Long Observation Period
Hypothesizing on the design of a recharge well is useful, but it must be trialled
in a real-world setting. It is proposed that of the recommended location for
injection well recharge, one site is chosen and bore be dug to the appropriate
depth i.e. twenty metres. An underground stormwater tank should be placed
in an area where rainfall and stormwater runoff capture is high. This
stormwater should then be redirected by gravity-fed pipe to the injection well.
Alternatively, a network of trenches that will capture rainwater and stormwater
can be diverted to the injection well instead.
2. Assessment of Groundwater Depth in Different Locations
This parameter will allow for the mapping of which areas receive the highest
amount of water. As groundwater flows from a north to south direction, it is
important to note that the site chosen for recharge is providing enough water
to residents around the area, as well as south of the area. Should it be found
that the area is not providing sufficient water, this will provide cause to move
the injection site to a more suitable location which will allow for groundwater to
be more accessible to a greater population.
3. Urban Obstruction
A note of potential urban obstruction should be recorded to ensure that any
interference to stormwater/rainwater capture and recharge from the injection
well. Also, it should be observed whether the appearance of an injection well
has caused any disruption the daily lives of locals in the area.
4. Rainfall Patterns and Total Capture
An observation of rainfall patterns should be observed to determine a rough
estimate of stormwater that is redirected to the injection well. This is
particularly useful when using a trench network to capture water. However, if
a water storage tank is used, a sensor is recommended to obtain an accurate
measurement of how much stormwater will be diverted to the injection well.
65
Groundwater Remediation Technologies on the Household Scale
It is highly recommended that the student applies for a permit from the Department
of Agriculture and Water Resources and ensure that all their samples arrive in Perth.
From there, they will be able to test which technology is best for removal efficiency of
contaminants by constructing pilot projects of the different techniques outlined in the
Discussion (Chapter 6). Should they choose, they can also conduct a more
comprehensive chemical analysis to determine organic, iron and sulfidic
components.
The hope for future studies is to verify proposed techniques to present to Yogyakarta
for implementation of a sustainable groundwater management strategy.
66
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74
Appendix 1 – Tables and Measurements
DepthHydraulic
Conductivity
X Y m m/day
1 Ibu Ari, Grand Permata Residence, imogiri bantul -78,715,433 1,103,760,019 7.1 482 241 25 9 8.64 120
2 Ibu Darul , imogiri, bantul -7,918,669 1,103,834,132 7.2 472 236 26 7 8.05 120
3 Bapak Muji , imogiri, bantul -79,161,369 1,103,926,652 7.2 1214 608 27 7.88 8.3 120
4 Ibu Suwardi, kotagede, Kota Yogyakarta -7,825,752 110,397,876 6.7 416 209 32 10 7.9 140
5 Bapak Hidayat, Kotagede -7,831,591 110,397,472 6.7 548 274 29 3 8.5 140
6 Ibu Najib , Sleman -77,680,252 11,040,414,038 6.7 1195 398 27 10 8.64 140
7 Instiper University, maguwoharjo, sleman -7,760,774 110,424,994 6.9 260 132 28 9 8.15 100
8 Ibu Lasmini, maguwoharjo, Sleman -775,214 110,417,346 6.8 264 128 28 8 8 100
9 Ibu Yunani, godean, Kulonprogo -7,772,103 110,325,253 6.8 274 137 27 9 4.1 120
10 Ibu Wardanah (PDAM Kulonprogo), wates -78,678,256 1,101,702,076 7.5 186 105 25 5.1 3.2 100
11 Public Well, wates, kulonprogo -786,742 11,016,984 6.9 1388 664 28 3 2.9 380
12 Ibu Ningsih, Ngampilan,Sleman -780,003 110,359,876 7.1 518 274 25 10.2 6.1 200
13 SMPN 7 Yogyakarta, Kota Yogyakarta -7,791,394 110,350,931 6.8 318 163 24.5 18 6.1 120
14 Bapak Jatmiko, Sleman -77,400,056 1,103,393,076 6.7 258 135 26 10 8.4 140
15 Bapak Bambang, Canting Prodo Hotel, Sleman -776,788 110,439,883 6.8 306 153 25 9 6.45 140
16 Ibu Winda, Sambiroto, Sleman -774,131 110,444,069 7.3 263 118 28 10 6.3 120
17 Ibu Nana, near UGM selokan Matarm, Sleman -7,765,182 110,379,908 6.9 402 204 26 9 6.9 120
18 Ibu Bunga ,near selokan mataram, sleman -7,761,923 11,036,631 6.7 400 200 27 10 7.2 120
Temperature Alkalinity (ppm CaCO3)TDSLocationNo Coordinate Ph EC
Table 13 – Superficial Chemical Analysis of Groundwater in
Yogyakarta
Table 14 – Rainwater Analysis of Yogyakarta (Fadhila, Brontowiyono and
Juliani 2016)
75
Appendix 2 – Design Parameters for Aquifer
Recharge
Parameters for Stormwater Calculation of Infiltration Basin
Values
Area of Infiltration Basin (acres)
4.94211
Rainfall Intensity (inches/hour)
1.5748
Runoff Coefficient of Sandy Loam
0.1
Peak Flow Rate (ft3/sec) 0.778283483
Peak Flow Rate (m3/s) 0.022038533
Peak Flow Rate (m3/year) 695007.208
Parameters for Stormwater Calculation Values for Injection Well via Stormwater Tank
Area of Stormwater Tank (acres) 0.017176359
Rainfall Intensity (inches/hour) 1.5748
Runoff Coefficient of Clay 0.22
Peak Flow Rate (ft3/s) 0.005950853
Peak Flow Rate (m3/s) 0.000168509
Peak Flow Rate (m3/annum) 5317.751973
Peak Flow Rate (kL/annum) 5317.751973
Table 16 – Peak Flow Rate of Stormwater Using
Injection Wells via Stormwater Detention Tank
Table 15 – Peak Flow Rate of Stormwater
Using Infiltration Basin
76
Appendix 3– Breakdown of Costings
Equipment Cost/Unit ($) Total Unit Cost ($)
Drilling of 15 Metre Borewell
61.48/metre 922.2
116000 Litre Water Tank
11500 11500
Groundwater Pump
8000 8000
Installation of Groundwater Pump
6000 6000
Gravel Tube of 8.5 Metres Deep
8.20/metre 69.7
Grout Seal of 8.5 Metres Deep
$75.13/metres 638.605
Total Cost ($) 27,130.305
Table 17 – Costing Distribution of Injection
Well and Subsequent Stormwater Tank
(Environmental Protection Agency n.d.)
77
Appendix 4 – Sampling Procedures
(A) For water depth and hydraulic conductivity
1. Travel to individual sites used for groundwater extraction.
2. Measure the depth to the water table. A water sensor was developed to test
the hydraulic head at the site. A cylindrical instrument had a sensor attached
to its base. It is slowly lowered using a measuring tape, as shown in Figures 8
and 9. When the sensor detects water, the measurement from the tape is
taken. It was developed by Dr. Yureana Wijayanti.
3. In some locations where the outer wall of the bore prohibited ground-to-water
measurement, the measurement of the height of the well lips was taken as
well. This was subtracted from the value obtained in step 2 to obtain hydraulic
head from the ground.
4. In order to determine hydraulic conductivity, a permeameter was used. A
shallow hole was dug into surrounding soil and the saturated hydraulic
conductivity (i.e. Ksat) was measured accordingly and recorded.
5. Using water depth and hydraulic conductivity, computational software was
used to create models in order to determine which areas would be most
suitable for recharge.
Figure 30 – Side View of
Water Sensor Figure 31 – Bottom View of
Water Sensor
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(B) Sampling
Groundwater samples were analysed in terms of chemical composition. The
procedure for this explained below.
1. As per the sites shown in Map 4, testing is carried out to determine superficial
chemical parameters of the groundwater at each site, such as pH,
temperature, electrical conductivity (EC), total dissolved solids (TDS),
alkalinity and total alkalinity.
2. A pH meter was used to test for pH of groundwater samples; this also
provided a temperature reading. A probe was used to test EC (μs/cm). Using
the same probe, the amount of TDS (mg/L) was also observed.
3. A 10 mL sample of groundwater was collected in a small vial. Results of
alkalinity are determined using a colour test. If the sample turned red, then it
is acidic; conversely if the sample turned blue, it is alkaline in nature. A clear
solution implied neutrality.
4. Following the initial observation in Step 3, total alkalinity (ppm CaCO3) was
determined. A new 10 mL sample of groundwater was taken. An initial
fluorescein dye was used to turn the sample a yellow-amber colour. After this,
drops of a reagent were added and mixed in quick succession until a red-
orange hue was observed. Each drop was equivalent to 20 ppm CaCO3.
5. Once the above parameters had been tested, 500 mL samples of
groundwater were extracted at five locations and stored at 20°C, in order to
avoid any chemical transformations, most especially if there were any
thermotolerant bacteria.
6. Samples were sent to laboratories for chemical analysis. The data collected
from the analyses is presented in Chapter 5.
Depth of Groundwater (m)
Figure 32 – Initial
Observation of Alkalinity as
Outlined in Step 4
Figure 33 – Observation of
Total Alkalinity as Outlined in
Step 5
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