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

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

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

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

WHERE STORAGE IS INADEQUATE 5

WHERE THERE IS STORAGE 6 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

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 9 MAR

CLASSIFICATION OF 3R SOLUTIONS

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

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

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 m) originates from the river with travel times of 5-10 days (wet season) to days (dry season). BANK INFILTRATION:CHAPAI NAWABGANJ

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

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

17 3R solutions to improve Water Quality and Quantity 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 3D model was made to guide the testing and to be calibrated for future desings and upscaling INFILTRATION TESTING

UpozilaPopulation 2006 Area km 2 % affected Kaliganj Assasuni268, Syamnagar337, Batiaghata151, Paikgacha267, Koyra207, Dacope169, Rampal192, Mongla160, Morrelganj376, Sarankhola123, Total2,526,000 UPSCALING POTENTIAL SHALLOW GW INFILTRATION IN KHULNA AND SATHKIRA DISTRICT: Experiences can also be used to assess and test the application elsewhere in Bangladesh

SIMULATION MODEL RAINWATER HARVESTING

ECONOMIC VALUATION OF STORAGE: 3R CBA

OVERVIEW OF COST /BENEFITS OF STORAGE COSTITEMVALUATION CONSTRUCTIONIncl. design etcUSD ADDITIONAL COSTLand acquisition Power supply USD SOCIAL/ENV. COSTEIA/SIA / MitigationUSD - USD/yr O&MIncl.monitoringUSD/yr BENEFITSITEMVALUATION REDUCED COST OF WATERDrinking, livestock, rural industry, small scale irr. USD/yr, based on interviews INCR. PRODUCTIVITYSee above: income increase HOUSEHOLD BENEFITSImproved health, more timeIndirect, through valuation methods. SOCIAL / COMMUNITY BENEFITS Cohesion, security, education ENVIRONMENTAL BEN.Biodiversity, vegetation

Village household income (Rs thousand/yr) Bhalgudi18,00026,000 Chikhalgaon20,00028,000 Hadshi village24,00030,000 Nanegaon 62,000 Nadgaon 20,000 average20,66733,200 Location agricultural income (Rs thousand/yr) beforeafter USBed Dsbed Samrapur Vajapur Nedardi Control total Kolwan Valley 3 check dams Population 15,000 Catchment area 80 km2 EXAMPLES OF MEASURED BENEFITS : INDIA Satlana Carr 3 check dams/1 percolation pond Population 4250 Catchment area 20 km2

Thank you