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INTEGRATED COASTAL VULNERABILITY ASSESSMENT MODEL FOR BALI ISLAND

D.M.Sulaiman 1), R. W. Triweko 2), D. Yudianto3) Civil Engineering Graduate Program, 2Professor, Civil Engineering Graduate Program 3Lecture, Civil Engineering Graduate Program Parahyangan Catholic University Jalan Merdeka 30 Bandung 40117 INDONESIA Email : dedems@ymail.com, triweko@home.unpar.ac.id, doddi_yd@home.unpar.ac.id1Ph.D Student,

ABSTRACTVulnerability is defined as the extent to which a population or an ecosystem is liable to be affected by a hazard event . A Numerical assessment measures the probability of physical changes based on analysis of physical and human-interference variables. The approach model attempts to combine susceptibility with the ability of the system to adapt and to cope with these problems. Vulnerability indexes provide a measurement of vulnerability potential effected by natural and human induced sea level rise that likewise may contribute to or trigger an increasingly vulnerability. This study shall provide a more realistic vulnerability assessment model that shall not only illustrate physical vulnerability but also the threat to socio-economic and environment development. The vulnerability assessment method integrating two variables, namely physical and human influence variables that include also the influence of culture and traditional wisdom is expected to be a more integrated assessment model for the estimation of coast vulnerability. By including human induced activity into the vulnerability assessment model, more objective vulnerability indexes to improve management in coping with affected sea level rise, and preparation of strategy, anticipation and adaptation to climate change will be resulted . The application of the coastal vulnerability assessment model in Bali showed that both physical and human-interference variables had affected the coastal vulnerability of the island. Keywords: vulnerability assessment, coastal vulnerability indexes, physical variables, human interference variables, Bali Island

INTRODUCTIONIndonesia as an island nation and with a coast line of approximately 95.181 km, the fourth longest in the world (Rompas 2010), is extremely vulnerable to be affected by sea level rise (UNEP 2006). The vulnerability is aggravated by the population residing these coastal areas, i.e. approx imately 60% of the total population lives at a radius of 50 km within the beach line (Idris 2002). Sea level rise in Indonesia reaches an average of 5-10 mm per annum (MMAF 2009). This sea level rise is relatively small, but in the long range this increase will be of high significance causing serious impact to beach destruction. When adaptation attempts are not carried out and population growth not controlled, the scenario of one meter sea level rise in a time span of 100 years ahead may cause erosion and a beach retreat of 50 m (IPCC 2007). This serious condition of erosion may decrease coastal areas in Indonesia by approximately 4.759 ha per year, and millions of people have to be evacuated to higher grounds (MMAF 2009). Sea level rise and other related effects are estimated to cause serious impact to coastal areas along the north coast of Java, small islands like Bali, east coast of Sumatera, south coast of Kalimantan, southwest coast of Sulawesi, some coastal areas in West Papua (Kabupaten and Kota Sorong, Teluk Bintuni/Bentuni Bay and Merauke) (ADB 2001).

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_______________________________________________________________________Sea level rise as impact of global warming has become a serious threat to coastal communities, infrastructure and eco-system (Kaiser, 2007), and exacerbate to coastal areas (1) beach erosion, (2) inundated coastal plains, (3) tidal flooding, (4) salt intrusion into groundwater layer (Kana et al, 2004; Leatherman, 1989), (5) increase of flood frequency and intensity, (6) change of sea current and destruction of mangrove forests, and (7) disappearance of small islands (Gornitz, 2000). Other induced impacts are the decrease of productive agricultural land and the slow down of industrial and business activities due to damaged infrastructure (MMAF 2009). Coastal zones are therefore the most vulnerable areas to sea level rise (IPCC 2001). This study intends to put forth a model of vulnerability assessment to sea level rise and was tested on beach vulnerability in Bali. It is expected that this study may come out with a more realistic assessment model that shall not only illustrate physical vulnerability but also socio-economic and environmental vulnerability. Development of this model may result (1) coastal vulnerability maps depicting areas of high vulnerability for reference of policy makers, planners and stake-holders in anticipating impacts of climate change, and in preparing strategy, anticipation and adaptation to these impacts of change, (2) priority in coping with impact in accordance with area vulnerability, and (3) most vulnerable and dominant parameter used in the adaptation plan to impact of sea level rise.

LITERATURE REVIEWCoastal vulnerability is defined as : (1) the extent to which a population or an ecosystem is liable to be affected by a hazard event and be capable of coping with the hazard (UNEP, 2006); (2) the sensitivity of an eco-system and coastal community, individually or as a group to disaster, a condition triggered by a social-economic and environmental system, implies the capability of adaptation in coping with disaster in terms of carrying out preventive measures (Kaiser, 2007); and (3) sensitivity of a community and eco-system to susceptibility of loss and the capability of recovery (Kim et al, 2009). A hazard can maintain a hazard or become more dangerous changing into a disaster. Such depending on the level of vulnerability, particularly if hazard event interacts with human-interfered activity (Kim et al, 2009). Vulnerability has not only become the main concept in understanding the impact of climate change and natural disasters but is also the management tool in strategy development of coastal damage risk management. Several approaches were applied in the assessment of vulnerability of various coastal areas in the world (Nicholls et al, 2007). This assessment of coastal vulnerability is very substantial in determining high risk areas, why these areas are of high risk, and what measures are to be taken to mitigate these risks. Many methods of coastal vulnerability assessment were developed since 1991 and started first with development of the Common Methodology for Vulnerability Assessment by IPCC. In the concise method of adaptation and coastal vulnerability assessment, Kay and Travers (2008) collected at least 15 (fifteen) assessment methods comprising (1) IPCC Common Method, which includes seven steps of approach using monetary assessment in estimating vulnerability to sea level rise; (2) UNEP Method, provides a mind-set in responding to the problem of sea level rise and its impact; (3) Bruun Rule, estimates the responds to change of coastal profile because of sea level rise; (4) Shoreline Management Planning; (5) Coastal Vulnerability Indexes/CVI; (6) SPIM; (7) RamCo and Island Model; (8) SURVAS; (9) COSMO; (10) Community Vulnerability Assessment Tool/CVAT; (11)Dynamic Interactive Vulnerability Assessment / DIVA; (12) CoastClim and SimClim; (13) Reef Resilience Toolkit; (14) Smartline; and (15) CV & A. Almost all of these assessment methods stresses upon physical aspects only causing a separation between physical and socio-economic aspects (Nicholls and Small, 2002), and for a long time vulnerability assessment had particularly discussed the physical aspects. However, in recent years some studies had resulted more integrated vulnerability assessment methods that considered both physical and socio-economic/human-interference aspects. These combined variables produced an integrated and complete vulnerability index system (Boruff et al, 2005). Indicators are defined as the value obtained from several parameters that provides information and the illustration of a phenomena or the environment (OECD, 2003 following Kim et al, 2009). Indicator based vulnerability assessment provides a probability of explaining confusing and intangible reality in one single value. This can be done by reducing these confusing and intangible parameters or application of statistical analysis by a panel of experts (Kim et al, 2009).

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METHODOLOGY 1. Vulnerability Assessment TypologyThe indicator based coastal vulnerability assessment model attempts to account for resulting an index of coastal vulnerability to assess and estimate the risk of coastal area to hazards and its capability of coping with these hazards. From the many models of vulnerability assessment and the indexes resulted as shown on Table 1, vulnerability indexes can be divided into three types: (1) based on physical parameters ; (2) based on combined physical and social parameters ; and (3) based on combined physical, socio-economic , and environmental parameters . The first type initiated the currently used coastal vulnerability indexes as publicized by Gornitzt et al (1991), and the model of vulnerability assessment putting forth physical parameters is used as reference in other types of coastal vulnerability assessment model.

1)

Physical Vulnerability

Physical vulnerability is measured based on six physical parameters comp rising coastal geomorphology, beach line accretion, beach slope, sea level rise, significant wave height, and tidal range. This vulnerability index is commonly used in the United States, Canada, Australia, Greece, India, Malaysia and some other countries. The vulnerability index applied in Australia (Abuodha and Woodroffe, 2007), had developed it into 9 (nine) physical parameters with detailed geo morphological parameters according to type of rock, barrier, and slope. Although known as Coastal Sensitivity Index/CSI, and using different physical parameters, its method of assessment is similar with the model carried out by Gornitzt et al (1991). The Coastal Vulnerability Index/CVI as presented by Pendleton et al (2010), illustrates a series of coastal vulnerability divided into five levels of vulnerability , from lowest to very high, that may indicate the potential of vulnerability to physical changes when a change of sea level occurs. The CVI focuses on six parameters that directly influences the coastal change, i.e. geo-morphology, erosion or beach line accretion, beach slope, sea level rise, average significant wave height, and average tidal range. These parameters were selected to represent the coastal cha racteristics and physical process that influences beach condition without human interference. Two major variables in the assessment of coastal vulnerability, the geological and hydro-dynamics variables (see table 2), are the common standards applied in th determination of the coastal e vulnerability indexes by sea level rise. Whereas, from the six parameters used in determining these indexes, four of them are dominant and influencing parameters (Pendleton et al, 2010), namely geo-morphology, beach slope, sea level rise, and significant wave height. The two other parameters, tidal range and change of beach line are of no influence if these indexes are measured for an extensive beach (millions of kilometres). In order to maintain accuracy of the measurement of indexes, this study had used a relatively shorter beach segmentation method. Abuodha and Woodroffe (2010), had applied the same method for the southeast beaches in Australia. The physical variable based coastal vulnerability assessment method is related with the segmentation method ranking coastal segments according to semi-quantitative index. The Coastal Vulnerability Index is an example of one of the vulnerability assessment methods only concerned with physical influence. This method measures and ranks indexes based on parameters such as geo-morphology, beach slope, sea level rise, erosion or accretion of coastline, tidal waves, and average wave height. This vulnerability index was developed by the United States Geological Survey (Thieler and Hammer-Klose,1999). On the contrary, vulnerability assessment based on the human-interference variable uses socio-economic variables as its main component of analysis. Resulted index represents the total score of the social vulnerability index/ SoVI. Other methods that are based on social aspects is the Community Vulnerability Assessment Tool/CVAT which combines coastal socio-economic and environmental data, and the Dynamic Interactive Vulnerability Assessment/DIVA that analyzes a series of mitigation and adaptation scenarios. Geo-morphology is related with the landscape, characteristics, and process that shape the earth surface, above as well as below the sea surface, emphasizing on its genesis and future development and its context to the environment (Vestappen, 1983). The morphological parameter reflects the natural coastal landscape and its resilience to erosion (Thieller and Hammer-Klose, 1999). These parameters consist of steep beach slopes, medium beach slopes, sand dunes, gravel beaches, sand beaches or muddy beaches. The physical parameter of beach slopes gives an illustration and evaluation of possible erosion and flood potential. Relatively flat sloping coastal areas are more likely to be inundated by tidal

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_______________________________________________________________________floods or eroded than steep sloping areas (Pilkey and Davis, 1987). Other parameters include change of beach line, namely the retreat or progress of beach line to a fixed reference point on beach, usually a bench marking. The change of beach line is commonly episodic, seasonal, decennial or cennential. Beach erosion or accretion can be identified by comparing maps and aerial photos of former times. Sea level rise is a physical parameter decided by the average annual increase and decrease of sea level in a certain period of time observed at the tidal station. Global sea level rise ranges between 5-10 mm per year according to IPCC calculation ( 2007). The tidal range shows the difference between highest water level at high tide and lowest sea level at ebb. High tidal range is of low vulnerability, whereas on the contrary low tidal range has a high vulnerability (Thieler and Hammar-Klose, 1999). This opinion is based on the probability potential of extreme water level due to storms. In micro-tidal coastal areas, namely areas with a tidal range less than 2m, the probability of tidal floods is higher because of extreme water level exceeding highest water level in the coastal area. On the contrary, in macro-tidal areas with tidal range greater than 2m, the probability of inundation is very small because extreme water level during storm is lower than highest water level. Another physical parameter is the wave height which is a very substantial physical variable in determining coastal vulnerability. Wave attack may cause beach erosion, the higher waves the greater the erosion force, where wave energy approaching the coast is approximately the root of the ratio of high wave.

2)

Socio-economic Vulnerability

The socio-economic vulnerability index assesses coastal vulnerability according to socio-economic parameters, however with physical parameters still as the main factor. This social index was among others introduced by Boruff at al (2005) and applied in the assessment of coastal vulnerability to erosion in coastal villages throughout the United States. This socio-economic vulnerability index was also used in some South Pacific countries (Yamada et al, 1995), and South Africa (Hughes and Brundrit, 1992). The growth of population residing coastal areas and their economic development are important factors of contribution to coastal vulnerability, and these socio-economic parameters should therefore to be considered in the vulnerability assessment.

3) Socio-economic and Environmental VulnerabilityThis vulnerability index combining physical, socio-economic and environmental parameters is a more complete and reliable model complying with the definition of vulnerability that includes the sensitivity to disaster and capability of eco-system or community in coping with this disaster. This model was implemented in countries like Germany (Kaiser, 2007), South Pacific (Yamada et al, 1995), and Turkey (Ozyurt et al, 2008). Various impacts triggered by sea level rise such as the extension of eroded beaches and inundated areas are natural factors aggravating the coastal vulnerability. On the other hand, in coastal areas where pressure of socio-economic conditions have become more intense, excessive exploitation of coastal areas has rendered damage of the coastal eco-system. Coastal areas are not only been threatening by natural hazards due to climate change but also by humaninterference, uncontrolled development, conversion of coastal areas, and deforestation.

4)

Integrated Vulnerability Model

The vulnerability model involving all influential factors of coastal vulnerability, namely physical, socio-economic and environmental variables, is presently considered as the most complete model. By including the cultural parameter, this model is regarded as an integrated vulnerability assessment model and the conceptual coastal vulnerability assessment model used in this study. In particular natural conditions, coastal areas may have a moderate level of vulnerability. However, due to human-interference, like for example the construction of a port or sediment controller in the upstream, coastal areas have become more vulnerable. Beach erosion in coastal areas is exacerbated by the construction of these structures. On the contrary, vulnerability of coastal areas can be reduced by beach protection structures like groins, revetment or wave breaker. Apart from the physical parameters used in the vulnerability model by Gomitzt and Kanchiruk (1989), socioeconomic, environmental and cultural variables of human-induced activities are also used. The seven parameters proposed in the vulnerability assessment concept include: (1) coastal

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_______________________________________________________________________protection structure, (2) sediment controller, (3) coastal vegetation, (4) land-use, (5) groundwater consumption, (6) population rate, and (7) local tradition, see Table3.

Table 1 Vulnerability Indexes in Some Countries and Parameters UsedNo. 1 Name of Index Coastal Vulnerability Index (CVI) Country USA Parameter Used Relief, type of rock, morphology, relative sea level, change of beach line, tidal wave, maximum wave height Relief, type of rock, morphology, relative sea level, change of beach line, tidal wave, maximum wave height Location, infrastructure, hazard Natural vulnerability, tradition, institution, infrastructure, economic and human factors. Relief, type of rock, morphology, relative sea level, change of beach line, tidal wave, maximum wave height Geo-morphology, erosion/accretion, beach slope, relative sea level, average wave height and tidal waves Frequency of disturbances, relief SI plus exposure surge level , beach slope Analysis of social data census main components Combination of CVI and SoVI Reference Gornitz and Kanchiruk (1989) Gornitz et al (1991) Hughes and Brundrit (1992) Yamada et al (1995) Shaw et al (1998)

2

Coastal Vulnerability Index (CVI) Risk Matrix Sustainable Capacity Index (SCI) Sensitivity Index (SI)

USA South Africa South Pacific Canada

3 4

5

6

Coastal Vulnerability Index (CVI)

USA

Thieler and Hammer-Klose (2000) Petrick and Crooks (2000) Forbes et al (2003) Boruff et al (2005) Boruff et al (2005) Dukakis (2005)

7 8 9 10

Vulnerability Index Erosion Hazard Index Social Vulnerability Index (SoVI) Coastal Social Vulnerability Index (CSoVI) Coastal Vulnerability Index (CVI) Total Vulnerability Index Coastal Vulnerability Index (CVI) Vulnerability Index

UK Canada USA USA Greece

11

12 13 14

Germany Turkey Malaysia

15

Coastal Vulnerability Index (CVI) Coastal Sensitivity Index (CSI)

India

16

Australia

Geomorphology, erosion/accretion , beach slope, relative sea level, average wave height and tidal waves Socio-economic and environmental vulnerability Physical (erosion, tidal flood, inundation, salt water intrusion) and human interference Geomorphology, erosion/accretion, beach slope, relative sea level, average wave height and tidal waves Geomorphology, erosion/accretion, beach slope, relative sea level, average wave height and tidal waves Geomorphology, erosion/accretion, beach slope, relative sea level, average wave height and tidal waves

Kaiser (2007) Ozyurt et al (2008) Zakaria(2008)

Nageswara et al (2008) Aboudha and Woodroffe (2009)

The application of a coastal vulnerability assessment method that combines physical factors and human-interference variables, is expected to result a more integrated and realistic assessment

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_______________________________________________________________________method. The human-interference factors in the assessment model shall provide more objective indexes and improve coastal management in coping with the impacts of sea level rise and adaptation to climate change.

Table 2 Variable and Range of Indicator used in Deciding the Vulnerability Index No. 1. VariableGeomorphology

Very lowSteep slope >2 > 1.2 < 1.8 > 6.0 3.4 2.60

2 3 4. 5. 6.

Change of coast line Beach slope Sea level rise Tidal Range Wave height

-1.0 1.0 0.9 - 0.6 2.51 3.0 2.0 4.0 2.01 2.25

Source : Pendleton et al (2010) Table 3 Variable of Human Interference in deciding coastal vulnerability No. VariableHuman Interference Beach protection Sediment controller Coastal vegetation Land-use

Very Low>50 % < 20% >50 % Protected forest 80% < 5% Tourism

Groundwater consumption Population rate Local Culture

30-40% 500-1000 2-3

>50% >5000