Water supply vs Water Demand. CATCHMENT area

Transcription

1 Water supply vs Water Demand CATCHMENT area 1

2 Water supply vs Water Demand Supply Current status / availability of water resources Current status / availability of water infrastructure Dependence between water sources in the systems Water quality issues at sources and infrastructure Spa?al and seasonal differences in supply Technology op?ons based on water resources Demand Water uses: WASH, food produc?on, energy, ecosystem, etc Water users: nr of people, nr of schools, nr of health centres, etc Re-use poten?al between different uses Wate quality demands Spa?al and seasonal differences in demand Technology demand Does the supply meet the demand? 2

3 Water Demand Basic: Uses: domes?c (WASH), produc?ve Users: nr of households, nr of people Demands towards water quality à Field survey / mapping Second layer: Seasonal demand differences Now and the future (climate change, popula?on growth, etc) à Desk research 3

4 Example of water demand calcula?on (domes?c) Ward Nr of hh (2016) Expected nr of hh (2030) Nr of people (2016) Expected nr of people (2030) Litres per hh / day (2030) Litres per day/ ward (2030) Total 1,

5 Water demand considera?ons Is there compe??on between water for WASH and other uses (now and in the future)? Is there re-use poten?al between different uses? If there is already a specific technology demand, is this is the appropriate technology? 5

6 Water supply Basic: Current status / availability of water resources Current status / availability of water infrastructure Dependence between water sources in the systems Water quality issues at sources and infrastructure à Field survey / mapping Second layer: Spa?al and seasonal differences in supply Technology op?ons based on water resources à Desk research 6

7 Water demand vs supply Water resources Water infrastructure Water demand Groundwater: Surface water: Rainfall M3 / day M3 / day 7

8 Example of water supply Water resources Groundwater: river base flow, spring sources and wells hold water throughout the year (>1500 m3) Surface water: river, fluctua?ng but holding water throughout the year, and ponds withhold rainfall and runoff water (>400 m3) Rainfall: approximately mm per year, dry season from February to July (6 months) ExisJng water infrastructure At least 400 m3/ day through river intakes and piped system (es?ma?on based on informa?on that water is available throughout the year), at least 150 m3 from springs and wells Storage tanks (8): total volume 160 m3/day (based on average size of 20 m3 per storage tank, and assump?on that piped system will refill tanks during the night) Ponds (4): 400 m3 (assump?on 100 m3 per pond) All water resources have potenjal for use > 550 m3 per day 8

9 Water demand vs supply Water supply Water demand Sources Infrastructure Uses and Users Groundwater: river base flow, spring At least 400 m3/ day through river Domes?c: 40 litres p.p.p.d. sources and wells intakes and piped system (es?ma?on No of households: based on informa?on that water is available throughout the year), at No of people: Surface water: river, fluctua?ng but holding water throughout the year, and ponds withhold rainfall and runoff water Rainfall: approximately mm per year least 150 m3 from springs and wells Storage tanks (8): total volume 160 m3/day (based on average size of 20 m3 per storage tank, and assump?on that piped system will refill tanks during the night) Ponds (4): 400 m3 (assump?on 100 m3 per pond) Cacle: unknown, but all people have cacle, some have large herds of cows, ponds are used as well as river water Irriga?on: unknown, but there is a lot of irrigated (gravity-led) land and approximately 30% is used for sugar cane Fish farming: unknown, but some ponds are used for fish farming Total for domesjc uses > 550 m3 per day 364 m3 per day 9

10 Water demand vs supply P R G E - T = S P = Precipita?on R = Runoff G = total Groundwater ouglow ET = Evapo-Transpira?on S = Change in Storage

11 Water demand vs supply Scenario 1: No interven?on P = 500 mm E = 3% of P T = 2% of P R = 45% of P G = 10% of P Scenario 2: With Interven?ons P= 500 mm E = 3% of P T = 7% of P R = 15 % of P G = 15 % of P Es?mate how much storage (mm) is leh in the watershed in the two scenarios? Calculate the addi?onal amount of water (m3) retained in the catchment.