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Sri Lanka Rainwater Harvesting
Sri Lanka should focus on rainwater harvesting to address water scarcity issues. Historically, rainwater harvesting was practiced effectively during ancient kingdoms. Currently, population growth, urbanization, infrastructure limitations, and water wastage are reducing water supply. However, Sri Lanka receives adequate annual rainfall that could be harvested from roofs to meet demands. Focusing on rainwater harvesting would provide clean water and reduce stress on existing water systems.
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Sri Lanka Rainwater Harvesting
- 1. Sri Lanka Sri Lanka Rainwaterharvesting Rainwater harvesting Why Sri Lanka should concentrate on Why Sri Lanka should concentrate on Rainwater Harvesting Rainwater Harvesting I.DISSANAYAKE SRI LANKA
- 4. Introduction Introduction ƒ ƒ Definition Definition ƒ ƒ Rainwaterharvesting (RWH) is the capture and Rainwater harvesting (RWH) is the capture and storage of rainwater for purposes such as potable storage of rainwater for purposes such as potable and non potable uses, storm water abatement and and non potable uses, storm water abatement and landscape irrigation. It is a strategic tool and landscape irrigation. It is a strategic tool and proactive approach for drought mitigation and proactive approach for drought mitigation and alleviate water scarcity. alleviate water scarcity.
- 5. ƒ ƒ Roof rainwatercollection means getting clean Roof rainwater collection means getting clean water just from out side the door step. water just from out side the door step. ƒ ƒ It It’ ’s method is simpler, reduces fetching time, s method is simpler, reduces fetching time, economical, no toxic, no fluoride, minimize economical, no toxic, no fluoride, minimize health risk. health risk. ƒ ƒ Harvested rainwater can be particularly useful Harvested rainwater can be particularly useful when no other sources of water supply is when no other sources of water supply is available ,or if the available water supply is available ,or if the available water supply is inadequate or poor quality. inadequate or poor quality.
- 6. Historical perspective Historical perspective ƒ ƒTraditionally and Historically evolved methods of Traditionally and Historically evolved methods of RWH RWH ƒ ƒ The Great king The Great king Parakramabahu Parakramabahu – – Parakramabahu Parakramabahu (1153 (1153 - - 1186 A.D.) during 1186 A.D.) during Polonnaruwa Polonnaruwa kingdom. kingdom. “ “Not a single drop of water Not a single drop of water received from rain should be allowed to escape in to the sea received from rain should be allowed to escape in to the sea without being utilized for the benefit of human kind. without being utilized for the benefit of human kind.” ” Sigiriya Sigiriya Rock fortress Rock fortress. . In the 5th century, the In the 5th century, the construction of construction of Sigiriya Sigiriya rock fortress by the king rock fortress by the king Kasyapa Kasyapa was was the unique and magnificent showpiece with storage tanks and the unique and magnificent showpiece with storage tanks and swimming pools swimming pools etc.to etc.to present as rain water collection model. present as rain water collection model.
- 7. Water scarcity andor stress Water scarcity and or stress inadequacy of water supply to match the inadequacy of water supply to match the demand demand - -There are four main underlying causes There are four main underlying causes 1. Population increase and demand for Public 1. Population increase and demand for Public amenities amenities - - Land clearing and reclamation Land clearing and reclamation - - destruction to water bodies: destruction to water bodies: - - siltation affect to water sources, siltation affect to water sources, - - high demand for potable water and high demand for potable water and sanitation. sanitation.
- 8. Water scarcity andor stress Water scarcity and or stress inadequacy of water supply to match the inadequacy of water supply to match the demand demand 2. Urbanization and new townships 2. Urbanization and new townships - - Construction of new infrastructure, Construction of new infrastructure, new new condominiums condominiums - - demand for pipe borne water and demand for pipe borne water and sanitation. sanitation.
- 9. Water scarcity/stress Water scarcity/stress inadequacyof water supply to match the inadequacy of water supply to match the demand demand 3. Stress on pipe borne water supply 3. Stress on pipe borne water supply (infrastructure and financial limitations). (infrastructure and financial limitations). new water supply schemes, new water supply schemes, water supply infrastructure water supply infrastructure costly maintenance costly maintenance
- 10. Water scarcity andor stress Water scarcity and or stress inadequacy of water supply to match the inadequacy of water supply to match the demand demand 4. Pipe borne water wastage 4. Pipe borne water wastage - - Flushing, Flushing, - - Washing and gardening. Washing and gardening. - - public water wastage public water wastage - - water theft water theft
- 11. Water scarcity/stress Water scarcity/stress inadequacyof water supply to match the inadequacy of water supply to match the demand demand Direct causes Direct causes ƒ ƒ Surface water contamination Surface water contamination - - Natural reasons such as pollution, chemical and Natural reasons such as pollution, chemical and negligence negligence - - Agriculture waste Agro chemicals, nutrient Agriculture waste Agro chemicals, nutrient - - Discharging effluent by industries Discharging effluent by industries - - Dumping of Solid waste by local authorities and Dumping of Solid waste by local authorities and individuals individuals ƒ ƒ Natural phenomena Natural phenomena - -Geography, Geology naturally sloppy areas non Geography, Geology naturally sloppy areas non availability of water availability of water - -Seasonal cycles such as Drought Seasonal cycles such as Drought - -Disasters like earth slips . Disasters like earth slips .
- 12. Water scarcity/stress Water scarcity/stress inadequacyof water supply to match the inadequacy of water supply to match the demand demand ƒ ƒ Ground water resources depletion. Ground water resources depletion. - - Water extraction for agriculture, Shrimp Water extraction for agriculture, Shrimp farms, domestic uses farms, domestic uses - - Contamination due to salination, Contamination due to salination, Chemical and toxic substances Chemical and toxic substances - - Less seepage /ground absorption due to Less seepage /ground absorption due to concrete canals and drainage concrete canals and drainage - - Mining for sand, quarry, gem or other minerals Mining for sand, quarry, gem or other minerals
- 17. 1961 1961- -90 Annual 90 Annual Average Average2001 2001 2002 2002 2003 2003 2004 2004 2005 2005 2006 2006 Rainfa Rainfa ll ll mm mm No of No of Rainy Rainy days days Rainfal Rainfal l l mm mm No of No of Rainy Rainy days days Rainfal Rainfal l l mm mm No of No of Rainy Rainy days days Rainfal Rainfal l l mm mm No of No of Rainy Rainy days days Rainf Rainf all all mm mm No of No of Rainy Rainy days days Rainf Rainf all all mm mm No of No of Rainy Rainy days days Rainfal Rainfal l l mm mm No of No of Rainy Rainy days days Anuradhapura Anuradhapura Bandarawela Bandarawela Colombo Colombo Hambantota Hambantota Kandy Kandy NuwaraEliya NuwaraEliya Ratnapura Ratnapura Trincomalee Trincomalee 1285 1285 1572 1572 2424 2424 1050 1050 1840 1840 1905 1905 3749 3749 1580 1580 89 89 129 129 146 146 87 87 148 148 163 163 205 205 86 86 1262 1262 1539 1539 1933 1933 730 730 1922 1922 1681 1681 3264 3264 1431 1431 104 104 146 146 132 132 75 75 164 164 189 189 205 205 103 103 1260 1260 1602 1602 2100 2100 982 982 1927 1927 1517 1517 3202 3202 1725 1725 99 99 147 147 174 174 95 95 171 171 186 186 215 215 83 83 1192 1192 1498 1498 2030 2030 1273 1273 1502 1502 1374 1374 4021 4021 1425 1425 97 97 136 136 158 158 97 97 158 158 170 170 209 209 97 97 1444 1444 1591 1591 1958 1958 1165 1165 1565 1565 1741 1741 3742 3742 1926 1926 114 114 154 154 162 162 104 104 168 168 206 206 229 229 118 118 799 799 1516 1516 2814 2814 978 978 1784 1784 1347 1347 3405 3405 1792 1792 87 87 155 155 163 163 82 82 179 179 188 188 211 211 87 87 1324 1324 2081 2081 2723 2723 1334 1334 2121 2121 2555 2555 3736 3736 78 78 93 93 177 177 173 173 133 133 188 188 219 219 243 243 15 15 Met. stations Met. stations Rainwater Potential Rainwater Potential RAINWATER AVAILABILITY RAINWATER AVAILABILITY Annual rain fall and rainy days Annual rain fall and rainy days Source: Central Bank reports
- 18. Rainwater harvesting potential Rainwaterharvesting potential Data on roof and rainfall Data on roof and rainfall (TWD web site) (TWD web site) Roof top area Roof top area ( (Sq.m Sq.m) ) Rain fall (mm) and flow efficiency between 85 Rain fall (mm) and flow efficiency between 85- -90% 90% 100 100 200 200 300 300 400 400 500 500 600 600 800 800 1000 1000 1200 1200 1400 1400 1600 1600 1800 1800 2000 2000 HARVESTED WATER FROM ROOF TOP (Cum) HARVESTED WATER FROM ROOF TOP (Cum) 20 20 1.6 1.6 3.2 3.2 4.8 4.8 6.4 6.4 8 8 9.6 9.6 12.8 12.8 16 16 19.2 19.2 22.4 22.4 25.6 25.6 28.8 28.8 32 32 30 30 2.4 2.4 4.8 4.8 7.2 7.2 9.6 9.6 12 12 14.4 14.4 19.2 19.2 24 24 28.8 28.8 33.6 33.6 38.4 38.4 43.2 43.2 48 48 40 40 3.2 3.2 6.4 6.4 9.6 9.6 12.8 12.8 16 16 19.2 19.2 25.6 25.6 32 32 38.4 38.4 44.8 44.8 51.2 51.2 57.6 57.6 64 64 50 50 4 4 8 8 12 12 16 16 20 20 24 24 32 32 40 40 48 48 56 56 64 64 72 72 80 80 60 60 4.8 4.8 9.6 9.6 14.4 14.4 19.2 19.2 24 24 28.8 28.8 38.4 38.4 48 48 57.6 57.6 67.2 67.2 76.8 76.8 86.4 86.4 96 96 70 70 5.6 5.6 11.2 11.2 16.8 16.8 22.4 22.4 28 28 33.6 33.6 44.8 44.8 56 56 67.2 67.2 78.4 78.4 89.6 89.6 100.8 100.8 112 112 80 80 6.4 6.4 12.8 12.8 19.2 19.2 25.6 25.6 32 32 38.4 38.4 51.2 51.2 64 64 76.8 76.8 89.6 89.6 102.4 102.4 115.2 115.2 128 128 90 90 7.2 7.2 14.4 14.4 21.6 21.6 28.8 28.8 36 36 43.2 43.2 57.6 57.6 72 72 86.4 86.4 100.8 100.8 115.2 115.2 129.6 129.6 144 144 100 100 8 8 16 16 24 24 32 32 40 40 48 48 64 64 80 80 96 96 112 112 128 128 144 144 160 160 150 150 12 12 24 24 36 36 48 48 60 60 72 72 96 96 120 120 144 144 168 168 192 192 216 216 240 240 200 200 16 16 32 32 48 48 64 64 80 80 96 96 128 128 160 160 192 192 224 224 256 256 288 288 320 320 250 250 20 20 40 40 60 60 80 80 100 100 120 120 160 160 200 200 240 240 280 280 320 320 360 360 400 400 300 300 24 24 48 48 72 72 96 96 120 120 144 144 192 192 240 240 288 288 336 336 384 384 432 432 480 480 400 400 32 32 64 64 96 96 128 128 160 160 192 192 256 256 320 320 384 384 448 448 512 512 576 576 640 640 500 500 40 40 80 80 120 120 160 160 200 200 240 240 320 320 400 400 480 480 560 560 640 640 720 720 800 800 1000 1000 80 80 160 160 240 240 320 320 400 400 480 480 640 640 800 800 960 960 1120 1120 1280 1280 1440 1440 1600 1600 2000 2000 160 160 320 320 480 480 640 640 800 800 960 960 1280 1280 1600 1600 1920 1920 2240 2240 2560 2560 2880 2880 3200 3200 3000 3000 240 240 480 480 720 720 960 960 1200 1200 1440 1440 1920 1920 2400 2400 2880 2880 3360 3360 3840 3840 4320 4320 4800 4800
- 19. Benefits from rainwater Benefitsfrom rainwater ƒ ƒ Reduce water stress Reduce water stress to the people who practice RWH to the people who practice RWH ƒ ƒ Time Time saving from fetching of water saving from fetching of water ƒ ƒ Health Health- - reduce water contamination reduce water contamination ƒ ƒ Cost of water Cost of water- - No or less: water bills, water No or less: water bills, water bowser bowser cost, cost, transport expenses transport expenses. . ƒ ƒ Living condition Living condition improvement by improvement by labour labour time saving and water for better sanitation time saving and water for better sanitation ƒ ƒ Support to environment Support to environment water replenishment water replenishment ƒ ƒ Reduce stress Reduce stress to govt. by reducing heavy investment on to govt. by reducing heavy investment on infrastructure and it infrastructure and it’ ’s maintenances. s maintenances.
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- 21. Measures to beconsidered for future Measures to be considered for future ƒ ƒ - -Integrated approach Integrated approach – –Public, NGOO, CBOO, Public, NGOO, CBOO, Govt Govt, institutions, , institutions, local authorities and village level other organizations. local authorities and village level other organizations. ƒ ƒ - -Government patronage. Government patronage.- - Concessions, subsidies, Tax rebates, Concessions, subsidies, Tax rebates, govt govt sponsored funding arrangements such as matching grants. sponsored funding arrangements such as matching grants. ƒ ƒ - -Develop mechanism based on policy Develop mechanism based on policy- -. individual Activity based . individual Activity based work work programme programme ƒ ƒ - -New schemes for implementation New schemes for implementation - - Public private partnership Public private partnership programmes programmes ƒ ƒ - -Reduce misconceptions among people Reduce misconceptions among people- -Measure to improve Measure to improve rainwater quality for people to believe value of rainwater rainwater quality for people to believe value of rainwater ƒ ƒ - -Show benefits Show benefits- - improvement to livelihood, economic benefits, improvement to livelihood, economic benefits, improve sanitation. improve sanitation. ƒ ƒ - -Creation of Awareness Creation of Awareness – –Different types of awareness Different types of awareness programmes programmes ƒ ƒ - -Make Legal /mandatory requirement Make Legal /mandatory requirement – –Such as Chennai/ Such as Chennai/ bangalore bangalore India, selected cities in Japan ,Texas USA, India, selected cities in Japan ,Texas USA,
- 22. Future interventions Future interventions Issues IssuesProgramme Programme Activities Activities Benefits Benefits No policy No policy interventions interventions Non availability of Non availability of integrated integrated approach approach Lack of Lack of arrangement for arrangement for water quality water quality checking checking Lack of awareness Lack of awareness and education and education programme programme Policy based development Policy based development approach approach Introduce legislative Introduce legislative support: flood support: flood mitigation, Building and mitigation, Building and apartment construction apartment construction approval with (COC) approval with (COC) Road development; Road development; NWSDB by laws NWSDB by laws development development Stormwater Stormwater control, control, Reduction in Cost to Reduction in Cost to govt govt for water infrastructure for water infrastructure Water security and Water security and confidence in confidence in water availability water availability Integrated approach for Integrated approach for development development Public participation, Public participation, Govt Govt patronage and patronage and support; NGOO support; NGOO involvement; village level involvement; village level community group community group involvement; identify involvement; identify role of the individual role of the individual group group Collective effort; cost Collective effort; cost reduction; establish reduction; establish equity; fulfilling actual equity; fulfilling actual requirements; reduce requirements; reduce misconceptions. misconceptions. Scientific approach Scientific approach Water quality checking Water quality checking at intervals; Involve at intervals; Involve relevant agencies for relevant agencies for advises and field work advises and field work coordination. coordination. Get confidence on water Get confidence on water quality; development of quality; development of proper mechanism for proper mechanism for field field programmes programmes; Better ; Better coordination with coordination with relevant groups relevant groups Awareness and education Awareness and education programmes programmes Schools, temples and Schools, temples and larger institutions based larger institutions based programmes programmes for for implementation. implementation. Creation of awareweness Creation of awareweness among relevant groups among relevant groups and reduce and reduce misconceptions and misconceptions and popularize RWH popularize RWH
- 23. Future interventions Future interventions Needfor Need for demonstratio demonstratio n tank n tank construction construction programmes programmes Demonstration effect Demonstration effect Sponsored Sponsored activities; activities; demonstration demonstration tanks tanks construction construction Encourage people ;create tendency to Encourage people ;create tendency to have and own tank and popularize have and own tank and popularize tank construction. tank construction. Assessment Assessment for incentives for incentives No institution No institution interested in interested in RWH RWH Concessions and Concessions and incentives incentives Tax rebates ,tax Tax rebates ,tax incentives; incentives; grants or grants or matching matching grants; grants; material material supply. supply. Cost reduction in tank construction, Cost reduction in tank construction, more demand for water harvesting. more demand for water harvesting. Institutional Institutional arrangements for arrangements for RWH. Higher level RWH. Higher level commitment. commitment. Study Study infrastructure infrastructure requirements requirements Benefit to the water authorities; Benefit to the water authorities; reduction of monthly water expenses reduction of monthly water expenses to the institution to the institution
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