Dr. A.F.M Afzal Hossain 1 , PEng. Dr. A.F.M Afzal Hossain 1 , PEng. Saad Siddiqui 2 PEng. Saad Siddiqui 2 PEng. Md. Jakir Hossain 3 Md. Jakir Hossain 3 Zannatul Ferdous Haque 4 Zannatul Ferdous Haque 4 1 Deputy Executive Director (P&D); 2 Principal Specialist, HRD; 3 Senior Specialist, IRM, 4 Junior Engineer, R&D
Introduction Groundwater has been the main source of irrigation and other uses using a large number of deep (DTW) and shallow tubewell (STW) both by public and private initiatives In recent years, decline of groundwater table is observed in some areas due to over-abstraction of groundwater Lowering of groundwater table during dry months creates a problem for operation of STW and hand tubewell (HTW) Many ponds and tanks become derelict due to lowering of groundwater table creating shortage of water for both domestic use and use by the livestock population Arsenic contamination is also observed in some places of shallow groundwater along major river banks.
Policy Issues There are various water policies such as National Water Policy (NWPo) Integrated Water Resources Management (IWRM) National Environmental Management Action Plan (NEMAP)
Integrated Water Resources Management (IWRM) Integrated Water Resources Management (IWRM) is a process which promotes the coordinated development and management of water, land and related resources in order to maximize economic and social welfare in an equitable manner, holistically without compromising the sustainability of vital ecosystems and the environment Groundwater is a component of IWRM strategies although often neglected. The three E’s of IWRM (Economic efficiency, Environmental sustainability and social Equity) are the drivers of water sector reform, including groundwater
Sectoral Use of Groundwater (GW) Source: http://www.fao.org/nr/water/aquastat/data/query/results.html
Proportion of Water Demand (2025) Environment 9% Agriculture 32% Instream 56% Source: WARPO Water Supply 3%
Source: BBS, BADC, DAE & BMDA Irrigation Coverage ('000 Ha) 1000 2000 3000 4000 5000 6000 Trend of Irrigation Water use in 0 1979-80 1980-81 1981-82 1982-83 SW Irri, 1983-84 1984-85 Trend of Irrigation Development in Bangladesh 1985-86 1986-87 1987-88 Bangladesh 1988-89 GW Irri. 1989-90 1990-91 1991-92 1992-93 1993-94 Total Irri 1994-95 Year 1995-96 1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11
Geomorphic divisions of Bangladesh Alam et al, 1990
Groundwater Resources Monitoring Groundwater monitoring comprises the collection, analysis and storage of data on a regular basis to provide information for effective groundwater management to a variety of stakeholders.
Why Monitor? Assess and control the impacts and risks of human activities on groundwater quantity and quality Detect changes in groundwater storage, flow and quality during well field operation. Bridge knowledge gaps in the general understanding of the resource and its changes in time . Groundwater is also an indicator of climate change. Monitoring of groundwater levels and recharge rates will help build greater understanding of the resource and the possible impacts of climate change upon it.
Effective Groundwater Monitoring Effective groundwater monitoring should be driven by a specific objective and the data collected should be systematically stored for future use The effectiveness of groundwater monitoring may be improved by careful attention to a) data collection network design b) system implementation and maintenance c) data management, interpretation and use d) accessible monitoring stations e) use indicator determinants to reduce analytical cost f) participatory monitoring amongst water users
Groundwater Level Monitoring BWDB has a network of GWL monitoring using 117 Observation wells IWM conducted a study in 2000 that was funded by JICA This study was to monitor the groundwater level scenario in central Dhaka as well as groundwater level at the peripheral rivers surrounding Dhaka city It was observed that the groundwater depletion in central Dhaka is about 3m whereas at the peripheral rivers, the groundwater level depletes 1.5-2m in dry period
Groundwater Abstraction in Dhaka city (2004-05) Abstraction balance by subsurface inflow, 3 ) of Total Groundwater Abstraction (699 Mm vertical recharge and mining Dhaka City 4% 4% 13.71% 18% Domestic supply Subsurface inflow and vertical recharge Commercial supply Industrial supply Mining Community supply 74% 86.29%
Without conjunctive use 1997 - Max depth, 25m GW - 98%
Without conjunctive use Without conjunctive use 2006 - Max depth, 35m 2016 - Max depth, 45m Population - 9.74 mill Population - 7.74 mill Abstraction - 507 Mm 3 Abstraction - 408 Mm 3 DTW - 387 Nos DTW - 312 Nos
With conjunctive use 1997 - Max depth, 15m SW - May-Oct GW - Nov-Apr
800 1500 600 2016 2016 1000 2006 400 2006 500 1997 1997 200 mm mm 0 0 -200 -500 -400 -1000 -600 -1500 -800 4000 3000 3000 2500 2016 2016 2000 2006 2006 2000 1500 1997 1000 1997 1000 mm mm 500 0 0 -500 -1000 -1000 -1500 -2000 -2000 -3000 -2500 4000 2500 2000 3000 2016 2016 1500 2000 2006 2006 1000 1997 1997 1000 mm mm Abstraction 500 0 Recharge 0 -1000 -500 Surplus -2000 -1000 Deficit -3000 -1500 Groundwater Balance of Dhaka City
• Groundwater use for agricultural production has significantly been increased over the time in North- west region • The other areas where groundwater is widely used are the domestic and drinking purposes • Contribution of groundwater for domestic water supply in rural and urban towns in northwest region is about 97% Trend of Groundwater Development in Northwest Region • The wide spread use of groundwater for drinking purpose has resulted in significant reduction in water borne diseases like cholera, diarrhea, dysentery, typhoid etc
• In some places of the north-west region, depth to groundwater table goes below 7.0 to 20.0 m • During the peak time of recharge, groundwater table almost regains to its original positions except some places of the area such as Tanore Thana • In these areas, recharge is less compared to the total abstractions • Decline of groundwater table is mainly occurred due to higher abstraction round the year
Groundwater Level Monitoring in Coastal Region Water Level Observation Well no: 15, Well ID: KO_L_2_3 -0.1 -0.3 -0.5 WL (mPWD) -0.7 -0.9 -1.1 -1.3 16-Mar-13 23-Mar-13 30-Mar-13 6-Apr-13 13-Apr-13 20-Apr-13 27-Apr-13 Date
Groundwater Quality Monitoring BWDB has a network of GWQ monitoring using 117 Observation wells Similarly DPHE, BMDA and BADC have their own monitoring system IWM installs and collects data from observation well using field kit and lab tests measuring the values of different parameter The values of each parameter compared with standard for agriculture and drinking to see whether the qualities are within safe limits
In the north-west (NW) region a study was conducted by IWM There is no Boron and Fluoride toxicity in the NW region Manganese concentration is high in some places which might create potability and palatability problems Nitrate contamination in groundwater is noticed in areas where open latrine is located in the vicinity of drinking water sources such as a hand tube well The study area possess no salinity problem except in a pocket area of Manda Upazila under Naogaon district In the early 90’s Arsenic contamination was observed in few HTWs of Chapai-Nawabgonj district in the southwestern part of the Barind area. However, in other part of the area, the arsenic content of groundwater from DTWs is <0.01 mg/L
Groundwater Quality Monitoring in Coastal Region Under Joint Action Research project IWM collects data from observation wells Electric Conductivity (EC) Electric Conductivity (EC) Observation Well no: 14, Well ID: KO_L_2_2 Observation Well no: 40, Well ID: KA_R_2_1 2500 6000 5750 2000 5500 EC (µs/Cm) 5250 EC (µs/Cm) 1500 5000 4750 1000 4500 4250 500 4000 21-Mar-13 28-Mar-13 4-Apr-13 11-Apr-13 18-Apr-13 25-Apr-13 1-Jan-13 16-Jan-13 1-Feb-13 16-Feb-13 4-Mar-13 19-Mar-13 4-Apr-13 19-Apr-13 5-May-13 Date Date
Constraints to GW use
Hard to Reach Areas for Water Supply in Bangladesh Source: WSP, 2012
Relationship between Arsenic distribution and Geology of Bangladesh BGS-DPHE, 2001 ; Alam et al. 1990
Distribution of Arsenic in Bangladesh Source: DPHE/BGS/DFID, 2000
Groundwater Quality Source: NWRD, WARPO, 2003
Why Use Groundwater Model Groundwater models are mainly used for resource assesment Groundwater models are also used to represent the natural groundwater flow in the environment Groundwater models try to predict the fate and movement of the chemical The models may be used to predict the effects of hydrological changes (like groundwater abstraction or irrigation developments) on the behavior of the aquifer Groundwater models are used in various water management plans for urban areas
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