Water supply vs Water Demand - wash-alliance.org · Water demand vs supply 9 Water supply Water demand Sources Infrastructure Uses and Users Groundwater: river base flow, spring

WatersupplyvsWaterDemand

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CATCHMENTarea

WatersupplyvsWaterDemandSupply Demand

Currentstatus/availabilityofwaterresources

Wateruses:WASH,foodproduc?on,energy,ecosystem,etc

Currentstatus/availabilityofwaterinfrastructure

Waterusers:nrofpeople,nrofschools,nrofhealthcentres,etc

Dependencebetweenwatersourcesinthesystems

Re-usepoten?albetweendifferentuses

Waterqualityissuesatsourcesandinfrastructure

Watequalitydemands

Spa?alandseasonaldifferencesinsupply Spa?alandseasonaldifferencesindemand

Technologyop?onsbasedonwaterresources

Technologydemand

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Doesthesupplymeetthedemand?

WaterDemand

Basic:•  Uses:domes?c(WASH),produc?ve

•  Users:nrofhouseholds,nrofpeople•  Demandstowardswaterquality

à Fieldsurvey/mapping

Secondlayer:

•  Seasonaldemanddifferences•  Nowandthefuture(climatechange,popula?ongrowth,etc)

àDeskresearch

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Exampleofwaterdemandcalcula?on(domes?c)

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Ward N r o f h h (2016)

Expected nr of hh (2030)

N r o f p e o p l e (2016)

Expected nr of people (2030)

Litres per hh / day (2030)

Litres per day/ward (2030)

1 76 99 456 593 270 26.676

2 37 48 222 289 270 12.987

3 42 55 252 328 270 14.742

4 118 153 708 920 270 41.418

5 124 161 744 967 270 43.524

6 155 202 930 1.209 270 54.405

7 117 152 702 913 270 41.067

8 197 256 1182 1.537 270 69.147

9 171 222 1026 1.334 270 60.021

Total 1,037 1.348 6222 8.089 2.430 363.987

Waterdemandconsidera?ons

•  Istherecompe??onbetweenwaterforWASHandotheruses(nowandinthefuture)?•  Istherere-usepoten?albetweendifferentuses?•  Ifthereisalreadyaspecifictechnologydemand,isthisistheappropriatetechnology?

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Watersupply

Basic:•  Currentstatus/availabilityofwaterresources•  Currentstatus/availabilityofwaterinfrastructure•  Dependencebetweenwatersourcesinthesystems•  WaterqualityissuesatsourcesandinfrastructureàFieldsurvey/mappingSecondlayer:•  Spa?alandseasonaldifferencesinsupply•  Technologyop?onsbasedonwaterresourcesàDeskresearch

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Waterdemandvssupply

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Waterresources Waterinfrastructure Waterdemand2016+2030Groundwater:Surfacewater:

Rainfall

M3/day M3/day

Exampleofwatersupply

Waterresources ExisJngwaterinfrastructureGroundwater: river base flow, spring sources andwellsholdwaterthroughouttheyear(>1500m3)

At least 400 m3/ day through river intakes andpiped system (es?ma?on based on informa?onthat water is available throughout the year), atleast150m3fromspringsandwells

Surfacewater: river,fluctua?ngbutholdingwaterthroughout the year, and ponds withhold rainfallandrunoffwater(>400m3)

Storagetanks(8):totalvolume160m3/day(basedon average size of 20 m3 per storage tank, andassump?on that piped system will refill tanksduringthenight)

Rainfall: approximately 1.500 mm per year, dryseasonfromFebruarytoJuly(6months)

Ponds(4):400m3(assump?on100m3perpond)

AllwaterresourceshavepotenJalforuse

>550m3perday

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Waterdemandvssupply

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Watersupply Waterdemand

Sources Infrastructure UsesandUsersGroundwater: riverbaseflow, springsourcesandwells

At least 400 m3/ day through riverintakesandpipedsystem(es?ma?onbased on informa?on that water isavailable throughout the year), atleast150m3fromspringsandwells

Domes?c:40litresp.p.p.d.Noofhouseholds:1.348

Noofpeople:8.089

Surface water: river, fluctua?ng butholding water throughout the year,and ponds withhold rainfall andrunoffwater

Storage tanks (8): total volume 160m3/day(basedonaveragesizeof20m3perstoragetank,andassump?onthat piped system will refill tanksduringthenight)

Cacle:unknown,butallpeoplehavecacle, some have large herds ofcows,pondsareusedaswellasriverwater

Rainfall:approximately1.500mmperyear

Ponds (4): 400 m3 (assump?on 100m3perpond)

Irriga?on:unknown,butthereisalotof irrigated (gravity-led) land andapproximately 30% is used for sugarcaneFish farming: unknown, but somepondsareusedforfishfarming

TotalfordomesJcuses

>550m3perday

364m3perday

Waterdemandvssupply

• P–R–G–E-T=△SP=Precipita?onR=RunoffG=totalGroundwaterouglowET=Evapo-Transpira?on△S=ChangeinStorage

Waterdemandvssupply Scenario1:Nointerven?on•  P=500mm•  E=3%ofP•  T=2%ofP•  R=45%ofP•  G=10%ofP

•  Scenario2:WithInterven?ons•  P=500mm•  E=3%ofP•  T=7%ofP•  R=15%ofP•  G=15%ofP

•  Es?matehowmuchstorage(mm)islehinthewatershedinthetwoscenarios?

•  Calculatetheaddi?onalamountofwater(m3)retainedinthecatchment.