Ground Water Management in Groundwater Demand and Use Groundwater - PowerPoint PPT Presentation

9/5/2013 National Workshop On Groundwater Management in IWRM Dhaka, Bangladesh Course Contents Ground Water Management in • Groundwater Demand and Use • Groundwater Occurrences Bangladesh: Policy and Institutional • Groundwater Development Constraints Arrangement in Bangladesh • Case Studies: – Arsenic – Dhaka City Dr. Kazi Matin Ahmed, Professor – Coastal Area Department of Geology • Existing Policies • Institution and Capacity University of Dhaka • Requirements for Management Groundwater : source of drinking water for 97% of Self Sufficiency in Rice Production the population Current access to safe water: 80% 1

9/5/2013 Demand for Groundwater in 2025 (WARPO Data) Irrigation and Groundwater GW Population in millions SW m 3 /s Region Other Rural m 3 /s SMAs Total Towns Areas DTW STW LLP SW 2.4 4.5 16.4 23.3 1 16 Irrigated Area ('000 Hectres) 6000 5000 SC - 3.4 10.6 14.0 0 10 4000 NW 2.3 11.0 28.9 42.2 1 29 3000 2000 NC 26.8 6.0 17.6 50.4 14 31 1000 NE - 3.5 14.1 17.6 0 12 0 3 5 7 9 1 3 5 7 9 1 3 5 7 SE - 4.0 14.2 18.2 0 13 8 8 8 8 9 9 9 9 9 0 0 0 0 - - - - - - - - - - - - - 2 4 6 8 0 2 4 6 8 0 2 4 6 8 8 8 8 9 9 9 9 9 0 0 0 0 EH 6.1 3.2 6.0 15.3 3 10 Irrigation Season Total 37.6 35.6 107.8 181 19 121 The Bengal Basin Geological Background Nepal • Geology of Bangladesh Himalayan Mountains Himalayan Mountains – Physiographic Shillong Massif Shillong Massif – Stratigraphy • References: Indian Indian Shield Shield – Books on Geology of Bangladesh – BGS Report on Arsenic Contamination of Groundwater in Bangladesh – Groundwater Task Force Report 2

9/5/2013 Occurrence of Groundwater: Geology & Landform Quaternary Geology of the Bengal Basin Aquifer System Nature of Aquifers Sediments Workshop on IWRM, Dhaka, 23-27 April 3

9/5/2013 Aquifer System Aqui- UNDP , 1982 Aggarwal BGS & JICA, 2002 GWTF , fer et al., DPHE, 2002 Units 2000 2001 1 Upper/ 1 st Upper Upper Upper Composite Aquifer Shallow Aquifer Holocene Aquifer Aquifer Aquifer Groundwater 2 Main 2 nd Lower Mid Aquifer Middle Regions (UNDP, Aquifer Aquifer Shallow Holocene Aquifer Aquifer 1982) 3 rd 3 Deep Deep Deep Late Aquifer Aquifer Aquifer Aquifer Pleistocene -Holocene Aquifer 4 Plio- Pleistocene Aquifer Hydrogeological Zones 89 90 91 92 Zone Geomorphology 26 Zone I 26 I Teesta Fan INDIA Groundwater 25 25 II Deltaic Plains Zone IV Zone III Zones (MPO, Zone III 24 24 III Pleistocene Uplands (W e s t B e n g a l) INDIA 1985) A INDIA Zone II IV Sylhet-Mymensingh 23 23 Depressions Zone V B Zone VI Coastal Plains V 22 22 B a y o f B e n g a l VI Complex Geology 21 21 89 90 91 92 4

9/5/2013 Spatial variability in seasonality and trends Spatial variability in seasonality and trends Seasonal groundwater flow Seasonal groundwater flow dynamics dynamics v Highest and lowest groundwater levels are observed in September and b April respectively a v higher seasonal Dhaka fluctuationsare observed in c the Brahmaputra and upper Ganges floodplains Groundwater levels are referenced to the PWD Declining Water Levels Declining Water Levels Seasonal – trend decomposition Seasonal trend decomposition Seasonal-Trend decomposition procedure based on Loess (STL) Original time series Seasonal component Trend component Residual component 5

9/5/2013 Major findings: current trends Major findings: current trends v Rapid declines (>1 m/year) in shallow groundwater levels in and around Dhaka – urban/industrial abstraction is drawing from long-term storage; low permeability of surface geology impedes direct recharge to shallow aquifer v Steady declines in groundwater levels (50-100 cm/year) occur in the NW, Change in long-term north-central and SW districts due to intensive abstraction for dry-season GW storage groundwater-fed irrigation v Declining groundwater levels (50-100 cm/year) during wet periods indicate the shallow aquifers are not completely recharged in many parts of the country v Rising groundwater levels (0-10 cm/year) are observed in southern deltaic and estuarine areas and these are associated with the sea level rise and local recharge As in West Bengal, India Development Constraints • Presence of arsenic • High salinity • Excessive dissolved chemical and radioactive elements • Lowering of water level • Occurrences of gravel • Occurrences of biogenic methane • Pollution from various sources • Overexploitation of groundwater • Hilly Terrain • Other Physical Constraints 6

9/5/2013 Over 5 million wells tested! Map of Arsenic Occurrence v Most severely affected areas 2002 2002-03 Survey 03 Survey 1998 1998-99 Survey 99 Survey are in the southern part of the deltaic plains v Some contamination in the north east, northwest is least contaminated v Hills in the southeast safe v Distribution is controlled by surface geology v Deeper wells are mostly safe Arsenicosis Patients Arsenic Contamination in Bangladesh 7

9/5/2013 How many wells are untested today? What if all the wells were tested? 100% • Recent data collected 90% from 35 affected Upazila 80% in 2007-08 demonstrate Percentage of tes 70% that about 30% wells are 60% untested 50% 40% • 1.5M wells untested in 30% affected areas 20% 10% • up to 4.4M people 0% BAMWSP UNICEF/ UNICEF/ Total Tested Projection unknowingly exposed 272 DPHE 20 DPHE 172 464 464 Safe 71% 91% 92% 73% 84% Unsafe 29% 9% 2% 27% 16% About 16% of 10 million wells would exceed the drinking water standard (50 ppb) if all wells were tested How many people drink water Understanding Depth Distributions containing >50 ppb As? GOB, 2002 8

9/5/2013 Sources of Arsenic Safe Water Arsenic Removal Technologies A –Household ARTs: Alcan, Nelima, Read F, Shawdesh, Sono B - Community ARTs: Sidko Sono 45-25 Sidko READ-F MAGC/ALCAN 34 Pond Sand Filter Dug Wells and Ring Wells Rain Water Harvesting (UNICEF PHOTOS) 9

9/5/2013 Rural Piped Water Systems Deep Tube Wells (GOB, 2002) (GOB, 2002) Arsenic Exposure Situation Arsenic Situation Analysis 2009 2009 • In 2009, about 5.6, 22 and 35 million people are exposed to >200, >50, > 10 ug/L As in drinking water. • Health implications: 1 in 14 adult deaths attributable to arsenic exposure, or about 43,000 to 56,000 deaths per year • Economic implications: ~0.5% of annual GDP in lost income http://www.unicef.org/bangladesh/knowledgecentre_6868.htm 10

9/5/2013 Community based Testing Program Sediment Samples and Color Coding (B) (A) WHITE (W) OFF-WHITE (OW) BLACK (B) RED (R) (A) Sediment samples from SASMIT-8 (HARIAN) New kit, UNICEF (US$85/300 tests) (B) Assigning project hypothesis colors with the help Data entry in the field directly on handheld Garmin GPS Map76Cx (US$164 ea.) of a Munsell Soil Color Chart Mozumder et al, 2011 Google Earth for quality control Dhaka: The Fastest Growing Megacity OVEREXPLOITATION AND CONTAMINATION OF GROUNDWATER IN DHAKA MEGACITY UNICEF 11

9/5/2013 Physical Growth of Dhaka UNICEF Water Demand and Supply Ground Water Surface Water 14% 86% Dhaka Water Works 12

9/5/2013 Depletion rate: 2.5-3.5 m/y Max depletion at Tejgaon, Khilgaon Piezometric level :55-73 m (IWM, 2008). Groundwater EC of Dhaka City (2005) 1970 1980 1995 2007 Contour showing Depth to GW hydrograph of Upper Dupi Tila GW table of Upper Dupi Tila demonstrates a steady down ward slope. as on June, 2007 (Source: IWM) Increased build up areas, reduced vertical Site Specific Artificial Recharge Rules for selecting sites of Technique Map definite artificial recharge methods recharge and deepening of wells No of Clay Locatio thickness Method ns (m) 10 – 15 6 Trench pit 40 – 50 6 Injection well 3 – 7 2 Dug well 5 – 15 Lateral trench with 3 vertical shaft 0 – 10 1 Spreading Technique 20 – 25 Retention pond with 2 well 25 – 35 2 En-echelon Dam 15 -30 2 Check dam Dhaka has high potential for Artificial Recharge 13

9/5/2013 Saline Groundwater in Coastal Aquifers BRACKISH GROUNDWATER IN COASTAL PLAIN AQUIFERS Legend 0 cm SLR (Area 9239 sqkm) 32 cm SLR (Area 10612 sqkm) 88 cm SLR (Area 14468 sqkm) Lack of Local Fresh Water Water Logging Due to Storm Surge 14

9/5/2013 Field Exploration for Site Selection Site Layout for Two Locations Chandipur School Compound Pond Layout plan of the MAR Test Site at Layout plan of the MAR Test Site at Deb DPHE Compound, Assasuni, Satkhira Prosad’s home, Gangarampur, Batiaghata Exploratory Drilling Collection of Cuttings Schematic Designs for Two Sites Large Diameter Well Drilling Methods • Rotary Drilling • Percussion Drilling Schematic cross-section of MAR test Schematic cross-section of MAR test site for rain and pond water infiltration site for pond water infiltration in in Assasuni Batiaghata 15

9/5/2013 Installation and Completion of Infiltration Wells Abstraction Sites in Khulna District Abstraction Sites in Satkhira District Abstraction Sites in Bagerhat Districts 16