Groundwater (GW) is an almost ubiquitous source of generally - PowerPoint PPT Presentation

JDS International Seminar ll Supervisor: Prof. Maki Tsujimura Content  Introduction  Objectives  Methodology  Findings Mohammad Tanvir Akkas  Summary 201326025 (M2)  Future Works December 15, 2014 December 15, 2014 1

 Groundwater (GW) is an almost ubiquitous source of generally high-quality fresh water. (Taylor et al., 2013) Fig: Per-capita groundwater resources in administrative units, in m 3 /(capita yr). Canada: 20366 USA: 2512 Japan: 798 Egypt: China: 490 India: 8 273 Bangladesh: 86 Australia: 13514 Falkland Island: > 10 6 (P. Doll et al., 2008)  GW in Highly Populated Area: Have lower per-capita groundwater resources < 1000 m3/(capita yr) (P. Doll et al., 2008) 2 December 15, 2014

 GW in Developing World:  Preferred as a source of potable water:  ready availability and  natural protection from contamination. (Hoque et al., 2007)  Developing countries in the tropics  Rapid Urbanization . (A. Gupta et. Al., 1997)  GW in Tropical Area:  In tropical landscapes where land-cover and land-use change have been rapid and complex; (J. Krishnaswamy et al., 2013)  GW in Flood Plain Area:  Groundwater resources are significantly influenced and extensively recharged by flood plain areas.  Extensive floodplains along large rivers play an important role in the hydrological cycle and water resources.  Reduction of inundation area reduce the GW recharge. (So Kazama et al., 2007) December 15, 2014 3

 GW in Delta Area:  Shallow aquifers underlying Asian mega-deltas are characterized by strong seasonal variations associated with monsoon rainfall. (M. Shamsudduha et.al. 2009)  In Ganga Delta aquifers, Rainfall and Floodwater  Groundwater (Ratan K et al., 2011)  In Humid region: Image: Wikipedia Unsolved Issues : Solved Issues  Contribution of Climate Change towards  Evolution of Groundwater chemistry Groundwater. with rapid urbanization.  Groundwater Recharge process in two  Groundwater and Surface water different aquifer system of floodplain interaction alluvium and Pleistocene clay zone.  During the 20th century, precipitation :  increased  In high northern latitudes  decreased  in some sub-tropical and lower mid-latitude regions. December 15, 2014 4 (Bovolo et al. 2009)

Monthly Precipitation in Bangladesh 600 Populated Humid 400 Developing mm 200 Bangladesh 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 35 Temp, °C 25 Delta Flood Tropical plain 15 Max and Min Temp in Bangladesh 5 Despite In Bangladesh, it has jan feb mar apr may jun jul aug sep oct nov dec  Alluvial flood plain  Sufficient rainfall (2400 mm)  Abundant surface water (800 River;  Tropical humid climate (10 ~ 35 °C) 24,140 km) (BMD, 2013) Suffering from GW issue for quantity and quality specially in the central region!  Dhaka is a vital central region of BD for its political and economical importance In Dhaka it is projected that So it is very much essential to  Water demand will double in next 15 years; understand the hydrology of  Land subsidence from 2000 to 2020 would be Dhaka city to study the reasons of its rapid GW drawdown; 6.4 cm; (IWM, 2008) 5 December 15, 2014

 In Bangladesh decreasing tendency of annual rainfall was indicated in Madhupur Tract (central region of Bangladesh). (Kazi, 2001)  Systematic groundwater development began in the city of Dhaka in 1949. (Ahmed et al. 1999)  More than 79% population of Dhaka relies on groundwater. (Dhaka WASA, 2013)  Due to the over extraction of groundwater, last 15 years the groundwater table declined Hoque et al., 2007 @ 3.5 meter/year. (Sultana, 2009) Fig: Surface Geology of Dhaka  Upper parts of the aquifer are already For better understanding the dewatered throughout the Dhaka city; hydrology Mohammad A. Hoque et al., 2007) of Groundwater of Dhaka it is  Due the intensive pumping, vertical leakage inevitable of relatively poor quality water may occur. to know its recharge process! (Sultana, 2009) 6 December 15, 2014

 To Identify the recharge sources of groundwater in Dhaka; Fig: Topographic map of Dhaka Densest Megacities Area: 360 km 2 ; of the world Water body: 48.56 km 2 density  45,000 Avg Altitude from Sea Level: 4 m pop/sq-km. (Joel Kotkin, Climate: Tropical Monsoon 2011) (Hoque et al. 2007) Temperature: 12~34 °C Population: 14.6 Annual Rainfall: 2150 mm million (World Bank, 2013 ) Dhaka city is situated in the Pleistocene uplifted block (Madhupur Tract) within the passive margin surrounded by subsiding floodplains. (Miah & Bazlee, 1968) River and canal 7 Source: Bangladesh Bureau of Statistics(2011), December 15, 2014

Annual Rainfall and Humidity in Dhaka 3500 78 (1982 ~ 2012) Rainfall 3000 76 Annual Avg Temperature of Dhaka Humidity 27 Humidity, % Temperature ( °C)  Aquifer and aquitard layers do not have similar gradient as surface topography. 2500 74 1982~2012 Rainfall, mm y = -11.772x + 2281.9 26.5  Overlying and underlying aquitard / aquiclude units separate all three aquifer 2000 72 26 1500 70 units. 25.5 1000 68  Abrupt change of hydrostratigraphic unit thickness in places without following 25 500 66 usual gradient. 1980 1990 2000 2010 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Year A 2 5 A` B A 1 …. 2 3 B 1 2 3 4 B` 5 4 B’ A’ Fig: Hydrostratigraphic cross section under Dhaka aquifer. December 15, 2014 8

B Chemical Analysis A. Statistical Analysis Field Survey: Organization: Sample Collection: • Bangladesh Meteorology Dept: Secondary Data SW, GW, Rain water Primary Data Meteorological data Time: • Dhaka WASA: GW depth (production Wet season well), Water production, Usage; Dry Season • BD Water Dev. Board: GW depth pH, EC, Temp (Monitoring well) • Isotope Analysis • Inst. of Water Modeling: Geological d 18 O, d D data, Assessment report • Inorganic ion analysis • BD Bureau of Statistics: Demography A. Existed Data B. Experimental date Anthropogenic & CC Issues Recharge Source December 15, 2014 9

Daily Groundwater Production & No of DTW 2000 700 1800 No of DTW 600 1600 Production Production, MLD 500 1400 No of DTW 1200 400 1000 300 800 DTW Operated by Private Agencies 600 200 400 2000 100 1719 1800 200 1600 No of DTW 0 0 1469 1400 Jul-98 May-99 Mar-00 Jan-01 Nov-01 Sep-02 Jul-03 May-04 Mar-05 Jan-06 Nov-06 Sep-07 Jul-08 May-09 Mar-10 Jan-11 Nov-11 Sep-12 Jul-13 1200 1000 691 800 Month 453 Source-wise Daily Water Production 600 400 2500.00 200 0 Jul-98 Aug-99 Sep-00 Oct-01 Nov-02 Dec-03 Jan-05 Feb-06 Mar-07 Apr-08 May-09 Jun-10 Jul-11 Aug-12 Sep-13 2000.00 Declining Production, MLD production Month in Zone 5 1500.00 The number of private Total Production boreholes has also increased Groundwater 1000.00 substantially and abstraction Surface Water through these wells remains 500.00 unquantified but is likely to be significant. (Hoque et al. 2007) 0.00 Jul-98 May-99 Mar-00 Jan-01 Nov-01 Sep-02 Jul-03 May-04 Mar-05 Jan-06 Nov-06 Sep-07 Jul-08 May-09 Mar-10 Jan-11 Nov-11 Sep-12 Jul-13 10 December 15, 20 Source: Dhaka WASA, 2013

Reasons might be:  Higher demand/pumpage comparatively to other;  Higher discharge;  Lower replenishment; “Abstraction is the main discharge from underlying aquifer system.” ( IWM, 2008) River and canal December 15, 2014 11

Fig: Distribution of production Well Need to consider the  Chemical Analysis of Groundwater and Surface water;  Contour lines of the GW table; 12 Source: Dhaka WASA, 2013 December 15, 20

Fig: Sample Location • Groundwater August 2014 (Rainy Season) • River water • Lake Water  Water Sample collection: GW: 39; SW: 14; HCO 3 Electrical Conductivity pH December 15, 2014 13 River and canal

Groundwater (deep) Fig: Stiff diagram of water samples of Dhaka. Lake water River water Na+K Cl Ca HCO 3 Mg SO 4 +NO 3 Fig: Piper diagram of water samples of Dhaka. 100% 0 ％ 0 ％ 0 ％ 100% 100% 100 ％ 0 ％ 0 ％ 100 ％ 0 ％ 0 ％ December 15, 2014 100 ％ 14 Ca 2+ Cl-

Static Water Level Pumping Water Level December 15, 2014 15

For downstream region: Production Well Stream Recharge Abstraction Aquifer December 15, 2014 16

 Extensive groundwater abstraction may be the primary reason of rapid GW drawdown;  Groundwater flow from the peripheral region towards central region leads the possibility of GW recharge from the river bed;  Water quality varies significantly from the down stream region to central and upstream region;  GW is mostly Ca-Mg-HCO 3 type;  Water samples are dominated by HCO 3 with a very low concentration of Cl - . SO 4 and NO 3 are almost nil.  Performing the Isotope ( d 18 O, d D ) analysis of the water samples ; 17 December 15, 2014