ACTION RESEARCH ON WATER BUFFERING IN BANGLADESH SCOPE

ACTION RESEARCH ON WATER BUFFERING IN BANGLADESH SCOPE AND OPTIONS FOR APPLICATION IN BANGLADESH Albert Tuinhof – Acacia Water Dhaka, 24 February 2011 Department of Public health Engineering University of Dhaka Geology Department

(GROUND)WATER BUFFERING IN BANGLADESH • • • Why is storage important ? Water buffering: the concept Technical options Possibilities in Bangladesh Examples/tools Cost and benefits

STORAGE: BETWEEN RESOURCE AND SUPPLY Resource mgt and water supply need more integration Water res. dev. & mgt. Water supply provision Source Abstraction Storage needed to bridge gaps in supply and demand Treatment Distribution Point of use

SOME FIGURES • Surface water storage per capita – Ethiopia 43 m 3 – South Africa 750 m 3 – North America 6150 m 3 • Village ponds or domestic rainwater storage could add 2 -5 m 3 person per annum • Each additional 10 mm groundwater recharge could add 50100 m 3 person per annum 4

WHERE STORAGE IS INADEQUATE 5

WHERE THERE IS STORAGE The Economist 22 May 2010 : In semi- arid Gujarat agriculture has grown at an average of 9. 6% since 2000, due to the creation of 500, 000 small ponds, dams and such like 6

STORAGE IS BUFFERING Its not about allocation scarce water but to catch and retain water and extend the chain of use and reuse as possible within a basin

MANAGING THE WATER BUFFER: THE CONCEPT Quick scan to assess hydrological, socio-economic and environmental conditions and water buffering needs on basin /catchment level Selection of appropriate Recharge, Retention and Reuse) interventions using tools and valuation techniques for decision making Focus on rural water livelihoods but also for urban ws and productive use Goal: upscaling (pilot projects) and integration of buffer management in IWRM /Basin Water Management

RAIN, SURFACE AND GROUNDWATER • Local tanks, surface water and subsurface storage (active use of aquifer) for both water- and food security • Subsurface storage (MAR) is largest potential in terms of quantity (m 3 ) and quality protection MAR 9

CLASSIFICATION OF 3 R SOLUTIONS

3 R and MAR: building infrastructure and/or modifying the landscape to intentionally enhance groundwater recharge Recharge enhancement provides additional storage

POTENTIAL IN BANGLADESH Tistafan Sandy deposits Barind Tract: Quantity Madhipur Tract: Overexploitation Sylhet: surface Clay and geology Flood Plains: Arsenic Coastal zone: Coastal: Salinity Chittagong Hills: Difficult Geology

POTENTIAL IN BANGLADESH

BANK INFILTRATION: CHAPAI NAWABGANJ Production wells drilled along the Mohanandan River abstract part of the water from the river. Simulations with a groundwater model and with a Bank Infiltration Simulator (NASRI) show that approximately 30% (dry season) to 60% (wet season) of the pumped water (at 30 -50 m) originates from the river with travel times of 5 -10 days (wet season) to 30 -40 days (dry season).

SAND STORAGE DAMS Abstraction well Subsurface storage - Capital cost : 8, 000 -12, 000 USD - Annual cost: O&Mand monitoring: 1, 000 -1500 USD - Water storage provided: 2, 000 m 3/rainy season - Number of users: 20 -30 families (100 -200 users)

SHALLOW GROUNDWATER INFILTRATION ACTION RESEARCH ON GROUNDWATER BUFERING IN BANGLADESH , PHASE 2 Infiltration testing Khulna Sundarbans Pilot Study of fresh WR in the coastal belt (IWACO, UNICEF, 1985)

INFILTRATION TESTING Fresh water from ponds and roofs can be injected in the shallow (brachish) aquifer during monsoon for abstraction during dry season 2 tests sites are constructed and tested after the 2010 monsoon 2 new sites will be added for testing during the 2011 monsoon A 3 D model was made to guide the testing and to be calibrated for future desings and upscaling 3 R solutions to improve Water Quality and Quantity 17

UPSCALING POTENTIAL SHALLOW GW INFILTRATION IN KHULNA AND SATHKIRA DISTRICT: Upozila Population 2006 Area km 2 % affected Kaliganj 275. 000 329 100 Assasuni 268, 000 377 100 Syamnagar 337, 000 1969 100 Batiaghata 151, 000 237 20 Paikgacha 267, 000 378 50 Koyra 207, 000 1583 100 Dacope 169, 000 1050 100 Rampal 192, 000 276 80 Mongla 160, 000 1502 100 Morrelganj 376, 000 439 95 Sarankhola 123, 000 Total 825 100 2, 526, 000 Experiences can also be used to assess and test the application elsewhere in Bangladesh

SIMULATION MODEL RAINWATER HARVESTING

ECONOMIC VALUATION OF STORAGE: 3 R CBA

OVERVIEW OF COST /BENEFITS OF STORAGE COST ITEM VALUATION CONSTRUCTION Incl. design etc USD ADDITIONAL COST Land acquisition Power supply USD SOCIAL/ENV. COST EIA/SIA / Mitigation USD - USD/yr O&M Incl. monitoring USD/yr BENEFITS ITEM VALUATION REDUCED COST OF WATER Drinking, livestock, rural industry, small scale irr. INCR. PRODUCTIVITY See above: income increase HOUSEHOLD BENEFITS Improved health, more time SOCIAL / COMMUNITY BENEFITS Cohesion, security, education ENVIRONMENTAL BEN. Biodiversity, vegetation USD/yr, based on interviews Indirect, through valuation methods.

EXAMPLES OF MEASURED BENEFITS : INDIA Kolwan Valley 3 check dams Population 15, 000 Catchment area 80 km 2 Satlana Carr 3 check dams/1 percolation pond Population 4250 Catchment area 20 km 2 Location USBed Dsbed Samrapur Vajapur Nedardi Control total Village Bhalgudi Chikhalgaon Hadshi village Nanegaon Nadgaon average agricultural income (Rs thousand/yr) before after 18. 00 36. 00 10. 00 28. 00 35. 00 16. 00 19. 00 15. 00 33. 00 22. 00 23. 00 household income (Rs thousand/yr) 1996 2004 18, 000 26, 000 20, 000 28, 000 24, 000 30, 000 62, 000 20, 667 33, 200

Thank you