Groundwater in LusakaGroundwater in LusakaG ou d ate usa aG ou d ate usa a-- A Resource in Need of Protection A Resource in Need of Protection --

Roland Bäumle & Levy MusetekaREPUBLICOF ZAMBIA

yFringilla Lodge, Feb 8th, 2011

Presentation OutlinePresentation Outline

1. Groundwater Pollution

2. Groundwater Protection

3. Vulnerability3. Vulnerability

4. Lusaka Groundwater Systems

5. Groundwater Chemistry and Quality in Lusaka

6. Conclusions

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World wide fresh water resources = 35 Mio. km3

Lakes 0 26% Rivers

Fresh groundwater

0,26% Rivers 0,0057%

Wetlands 0,033%Unsaturated soil 0,05%g

30,1% Atmosphere 0,04%

,

Ice and snow ( + glaciers and permafrost)( + glaciers and permafrost)

68,8%Source: Water for People, Water for Life – UN World Water

Development Report (WWDR); UNESCO 2003.REPUBLICOF ZAMBIA

Relevance of groundwater

Groundwater:

• worldwide most important resource for drinking water supply(nearly 60% of all drinking water worldwide is abstracted from groundwater,in arid and semi-arid zones up to 100% ! )

• in many countries used for agricultural irrigation(over 50% in Bangladesh, India and Iran; ca. 30% in Argentina, Mexico,and Pakistan; nearly 20% in China karst aquifers)and Pakistan; nearly 20% in China karst aquifers)

• secure water supply(natural protection against pollution important storage function during dry season)(natural protection against pollution, important storage function during dry season)

• relatively cheap to develop for rural water supply (local resource low development costs no sophisticated pipeline system needed(local resource, low development costs, no sophisticated pipeline system needed, in most cases no or only minor treatment costs)

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Groundwater Pollution in Urban AreasLand use activities commonly responsible for groundwater pollutionLand-use activities commonly responsible for groundwater pollution in the urban areaHow do aquifers become polluted?

When contaminants (effluents, discharge or leachate) are inadequately controlled and disposed of orexceed natural attenuation capacity of underlying soils and strata

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Common g/water contaminants & associated pollution sources

Pollution source Type of contaminantPollution source Type of contaminant

Agricultural Activity nitrates; ammonium; pesticides; faecal organisms

In-situ Sanitationnitrates; faecal organisms; trace synthetic hydrocarbonshydrocarbons

Gasoline Filling Stations & Garages

benzene; other aromatic hydrocarbons; phenolsStations & Garages

Solid Waste Disposal

ammonium; salinity; some halogenated hydro-carbons; heavy metalsDisposal carbons; heavy metals

Dry Cleaning trichloroethylene; tetrachloroethylene

Sewage Sludge nitrates various halogenated hydrocarbons lead Sewage Sludge Disposal

nitrates; various halogenated hydrocarbons; lead; zinc

chromium; various halogenated hydrocarbons; REPUBLICOF ZAMBIALeather Tanneries

chromium; various halogenated hydrocarbons; phenols

Peri-urban settlements

Present situation in many peri-urban settlements :Uncontrolled settlementPredominant use of on site-sanitationPredominant use of on site-sanitationUncontrolled waste dumpingWater supply predominantly from shallow wells or open water y yponds

Extensive contamination by nitrate,nitrite, ammonia, and faecal bacteria

Frequent outbreak of water-bornediseases (diarrhea, cholera).

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Contamination Sources

Source: Source: Nkhuwa 2006Nkhuwa 2006

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Contamination Pathway

Retention of solids

I fil i f li id

Soil:

Pathogens

Infiltration of liquids

P ll t d d tHigh water l l Nitrates

Viruses

Polluted groundwaterlevel:Short cut

Source: GTZ (Werner) 2005Source: GTZ (Werner) 2005

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Pathogenic germs

Unaffected groundwater is free of pathogenic germsUnaffected groundwater is free of pathogenic germsand is in good bacteriological conditions≈ 50 days of underground passage is sufficient to virtually kill all harmful bacteria

Empirical correlation of the so-called“50-day line”

Time in days

Mortality Rate in %REPUBLICOF ZAMBIA

Mortality Rate in %

Groundwater Protection

Protection of water resources by employing G/w Protection ZonesProtection of water resources by employing G/w Protection ZonesZone 1 – Immediate Protection ZoneProtects well/spring from direct contamination

WellI II III

Groundwater Flow Direction

contamination

Well

Zone III – Outer Protection ZoneZone II – Inner Protection ZoneProtects drinking water source against pathogenic constituents

Protects against contamination affecting drinking water source over long distances (for chemical substances REPUBLIC

OF ZAMBIA

g p gbacteria, viruses, parasites.

long distances (for chemical substances, which are non- or hardly degradable)

Protection ZonesGroundwater Protection Zones around well fields (public sector)Groundwater Protection Zones around well fields (public sector)

Graded protection and controlled use –To protect drinking water resources supplied from groundwater

Protection zone I has the highest priority(area directly surrounding the production well)

upstream of the well/spring from pollution.

Protection zone II:no groundwater pollutants and no industry

(area directly surrounding the production well)

and no industry, no untreated wastewater

Protection zone III

Zone III

limited use, construction/housing limited

Catchment areaCatchment Boundary

Zone II

Zone ICatchment BoundaryCatchment area

Integrated Water ResourcesManagement (IWRM)

BoundaryZone I

Well

Boundary

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Groundwater Protection Zones

Need regulatory embeddingNeed public awarenessNeed monitoringUsually imply land use restrictions to balance

ti i t tcompeting user interests.

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Definition of Vulnerability

Term Definition

S iti it t t i ti d t i d b th t lAquiferVulnerability

Sensitivity to contamination, determined by the naturalintrinsic characteristics of geological strata forming the overlyingconfining beds or vadose zone of the aquifer concerned

Threats to groundwater pollution are a function of:g pThickness & properties of overlying soilDepth to the water tableInfiltration rates and othersInfiltration rates, and others

A variety of vulnerability assessment tools may be used, e.g.: DRASTIC, PI methods

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How can groundwater pollution hazard be assessed?

Vulnerability Assessment

DRASTICDRASTICD - Depth to waterR N t R hR - Net RechargeA - Aquifer mediaS S il diS - Soil mediaT - TopographyI I f d I - Impact of vadose zoneC - hydraulic Conductivity

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Vulnerability Map

The ultimate goal of a vulnerability map is the subdivision of anThe ultimate goal of a vulnerability map is the subdivision of an area into several units showing the different degree of vulnerability.

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Lusaka Groundwater system in perspectiveLusaka Groundwater system in perspective

Lusaka is capital of Zambia with population of [at least] 1.3 million people with population growth rate of 3.7% per annum.Water supply coverage by municipal Service Provider (LWSC) is at 68%Water supply coverage by municipal Service Provider (LWSC) is at 68%. LWSC pumps 52% of water supply from groundwater. 48% comes from Kafue River 45km from Lusaka.

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Challenges

Karstic aquifer system characterized by shallow water tables andKarstic aquifer system characterized by shallow water tables and epikarstic zone extending between 5 and 25m Unregulated groundwater abstractiong gIncrease in unsafe disposal of solid and liquid waste in highly karstified aquiferS ll l iSmall-scale quarryingLow sanitation coverage of 17%

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Program to Develop Aquifer Management StrategyWater Quality Assessment

Hydrogeological InvestigationsG

Water Quality AssessmentPollution source/ risk

detectionVulnerability assessment

Groundwater balanceResource

t

Groundwater Information Groundwater Information System

Water point database

y

Remote SensingassessmentGroundwater

Modelling

Water point databaseHydrometric & water

quality monitoringGIS/Thematic Mapping

Remote SensingLand useKarst features &

geological structuresGIS/Thematic Mapping

D l t f d t

geological structures

Development of a groundwater management strategy

C lt tiR i P t ti Z i

Management guidelines

Consultative Process

Review Protection Zoning

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gg

Lusaka Groundwater SystemsPlateau of 3 000 sq km covering Lusaka City and adjacent parts ofPlateau of 3,000 sq.km covering Lusaka City and adjacent parts of Mwembeshi and Chongwe catchments

Quartzite & Schist

1. Main aquifer hosted by marbles of the Lusaka Dolomite – fast flowing GWLusaka Dolomite fast flowing GW

2. Subordinate aquifers within marbles of the Cheta formation located to the north and south – fast flowing GW

3. Minor Aquifers developed in schists and quartzites of the Cheta and Chunga formations and within alluvial deposits –l GW fl d filt tiREPUBLIC

OF ZAMBIA slower GW flow and more filtration

Lusaka Groundwater Systemsgroundwater flows (like surface water) from the higher (potential / water table) togroundwater flows (like surface water) from the higher (potential / water table) to the lower (potential / water table) Regional flow (shown here) but locally it can differ due to pumping of boreholes

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Some Past Water Quality studies conducted on the Lusaka Aquifers

ECZ, Lusaka Groundwater Contamination Assessment Project 2003. Concentrated ona) Libala Tipping sitea) Libala Tipping site. b) Leopard’s Hill –c) Lusaka industrial area )

UNEP, Assessment of pollution Status and Vulnerability of Water Supply Aquifers of African cities, 2005

Th t i t t t lit bl i th j t fThe most important water quality problem in the project areas of John Laing and Misisi is faecal pollution together with the associated disease-causing organisms Water from boreholes is less affected by bacteriological problems than that from shallow wells Conductivity and nitrate generally show elevated levels duringConductivity and nitrate generally show elevated levels during the dry season and lower concentrations during the wet season, probably resulting from dilution due to increased saturation in the aquiferREPUBLIC

OF ZAMBIA aquifer

GReSP Water quality sampling 2010

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Chemical Results GW Quality in Lusaka-Apr/May 2010

Piper DiagramResults groupedResults grouped

according to lithology and nitrate content

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Nitrate Spatial Presentation of Results

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ConclusionsUntreated wastewater from households and industry infiltrate into theUntreated wastewater from households and industry infiltrate into the soil and endanger aquifers and thus the drinking water supplyThe Lusaka Aquifer management strategy will depend on thorough assessment of:assessment of:

Groundwater potentialCurrent pollution statusPotential risks and vulnerability of the Lusaka groundwater system

Development of suitable management concepts that take specific situation in and around Lusaka into account

Thus decentralized sanitation and wastewater treatment concepts are some alternatives that could be usedThe concept of protection zones, the separation of abstraction, renewalThe concept of protection zones, the separation of abstraction, renewal and catchment area is essential for sustainable drinking water supplyIntegrated concepts can help in the long run to save considerable investments in water treatment and supply schemes as well as forinvestments in water treatment and supply schemes as well as for health services

Successful implementation will rely on institutional framework and capacitiesREPUBLIC

OF ZAMBIAcapacities

Thank youThank you

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http://www.bgr.bund.de/zambia