Dr. A.F.M Afzal Hossain 1 , PEng. Dr. A.F.M Afzal Hossain 1 , PEng. - - PowerPoint PPT Presentation

• Dr. A.F.M Afzal Hossain1, PEng.

Saad Siddiqui2 PEng.

• Md. Jakir Hossain3

Zannatul Ferdous Haque4

1Deputy Executive Director (P&D); 2Principal Specialist, HRD; 3Senior Specialist, IRM, 4Junior Engineer, R&D

• Dr. A.F.M Afzal Hossain1, PEng.

Saad Siddiqui2 PEng.

• Md. Jakir Hossain3

Zannatul Ferdous Haque4

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) 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

• ften neglected. The three E’s of IWRM (Economic

efficiency, Environmental sustainability and social Equity) are the drivers

• f

water sector reform, including groundwater

Integrated Water Resources Management (IWRM)

Sectoral Use of Groundwater (GW)

Source:

http://www.fao.org/nr/water/aquastat/data/query/results.html

Environment 9% Agriculture 32% Water Supply 3% Instream 56% Source: WARPO

Proportion of Water Demand (2025)

Trend of Irrigation Water use in Bangladesh

1000 2000 3000 4000 5000 6000 1979-80 1980-81 1981-82 1982-83 1983-84 1984-85 1985-86 1986-87 1987-88 1988-89 1989-90 1990-91 1991-92 1992-93 1993-94 1994-95 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 Irrigation Coverage ('000 Ha) Year

Trend of Irrigation Development in Bangladesh

SW Irri, GW Irri. Total Irri

Source: BBS, BADC, DAE & BMDA

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

• n 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

Total Groundwater Abstraction (699 Mm

3) of

Dhaka City

74% 18% 4% 4% Domestic supply Commercial supply Industrial supply Community supply

Abstraction balance by subsurface inflow, vertical recharge and mining

86.29% 13.71% Subsurface inflow and vertical recharge Mining

Groundwater Abstraction in Dhaka city (2004-05)

Without conjunctive use 1997 - Max depth, 25m GW - 98%

Without conjunctive use 2016 - Max depth, 45m

Population - 9.74 mill Abstraction - 507 Mm3 DTW - 387 Nos

Without conjunctive use 2006 - Max depth, 35m

Population - 7.74 mill Abstraction - 408 Mm3 DTW - 312 Nos

With conjunctive use 1997 - Max depth, 15m SW - May-Oct GW - Nov-Apr

• 1500
• 1000
• 500

500 1000 1500 mm

1997 2006 2016

• 3000
• 2000
• 1000

1000 2000 3000 4000 mm

1997 2006 2016

• 1500
• 1000
• 500

500 1000 1500 2000 2500 mm

2016 2006 1997

• 3000
• 2000
• 1000

1000 2000 3000 4000 mm

1997 2006 2016

• 800
• 600
• 400
• 200

200 400 600 800 mm

1997 2006 2016

• 2500
• 2000
• 1500
• 1000
• 500

500 1000 1500 2000 2500 3000 mm

1997 2006 2016

Abstraction Recharge Surplus Deficit

Groundwater Balance of Dhaka City

Trend of Groundwater Development in Northwest Region

• 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%

• The

wide spread use

• f

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

• 1.3
• 1.1
• 0.9
• 0.7
• 0.5
• 0.3
• 0.1

16-Mar-13 23-Mar-13 30-Mar-13 6-Apr-13 13-Apr-13 20-Apr-13 27-Apr-13 WL (mPWD) Date

Water Level Observation Well no: 15, Well ID: KO_L_2_3

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

• pen 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

• f 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

500 1000 1500 2000 2500 21-Mar-13 28-Mar-13 4-Apr-13 11-Apr-13 18-Apr-13 25-Apr-13

EC (µs/Cm) Date

Electric Conductivity (EC) Observation Well no: 14, Well ID: KO_L_2_2

4000 4250 4500 4750 5000 5250 5500 5750 6000 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

EC (µs/Cm)

Date

Electric Conductivity (EC) Observation Well no: 40, Well ID: KA_R_2_1

Under Joint Action Research project IWM collects data from observation wells

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

• r

irrigation developments) on the behavior of the aquifer

 Groundwater models are used in various water management

plans for urban areas

 Being able to model groundwater systems can be

tremendously useful for a wide range of applications

 Using a model helps people visualize a system which they

cannot see, and it can illustrate key points of interest or be used to gather information about a system

 People who have difficulty understanding water use

policy and other issues sometimes benefit from instruction with a groundwater model in which issues are visually illustrated

Groundwater Modelling Tools:

IWM uses three complete packages of mathematical

• modelling. These are:

 MIKE SHE  MODFLOW  FEFLOW

 MIKE SHE is a fully distributed, physically-based

hydrologic model that can simulate water movement over and under the earth's surface

 MIKE SHE can be used for the analysis, planning and

management of a wide range of water resources and environmental problems related to surface water and groundwater

 Five basic modules of MIKE SHE water movement are:

Overland Flow, Channel/River Flow, Evapotranspiration, Unsaturated Flow and Saturated/Groundwater Flow

Evapotranspiration Overland Flow River Flow Flow in Unsaturated Zone Groundwater Flow

Approach

• US Geological Survey (USGS) originated Visual MODFLOW is

an easy-to-use modeling environment for practical applications in three-dimensional groundwater flow and contaminant transport simulations

• It is a finite difference model, which solves a system of

equations describing the major flow and related processes in the hydrological system

• Visual MODFLOW simulates three-dimensional ground-water

flow through a porous medium by using a finite-difference method

FEFLOW

FEFLOW is the first complete groundwater modeling software package to successfully combine powerful graphical features with sophisticated analysis tools and robust numerical algorithms for:

 Density-dependent flow (salt water intrusion)  Transient or steady-state flow  Saturated and unsaturated flow  Multiple free surfaces (perched water table)  Mass and heat transport

FEFLOW has been specifically designed to meet the advanced technology requirements of expert modeling professionals involved in complex groundwater modeling projects

B a y o f B e n g a l

Fourth Dhaka Water Supply Project Meghna Dhonagoda Irrigation Project North Bangla Deep Tube Well Project

Modelling Technique used in Selected GW Projects

Conjunctive use Model for SW/GW interaction in CAD Project for Teesta Barrage Pilot Conjunctive use Model for SW/GW interaction in lower Atrai Deep Tube Well Installation Project in Barind Area BMDA Unit 2 BMDA Phase-III

Coverage of Coarse Groundwater Models at IWM

Case Study on GW Model in Barind Area (Phase-1)

Project Map of 25 Thana in Rajshahi, Nawabganj & Naogaon Districts

Project Covers 25 thana

• f Rajshahi, Nawabganj

& Naogaon Districts Total Area = 750,000 ha Cultivable Area = 595,760 ha Population = About 2 million Rainfall ~ 1200 to 1700 mm Nos of DTW = 6047 Nos of STW ~ 70,000

Data Collection & Processing

Topography, Cross Section Survey & Geo-referencing Hydro-meteorological & Hydrological Data Hydro-geological Investigation Soil Sample Testing & Analysis Percolation and Seepage in the Paddy Field Hydro-Geochemical Investigation Land Use and Vegetation Water Abstraction and Irrigation by Different Modes

Objectives of the study

• Assessment
• f Thana wise available safe groundwater

resources and recharge potential using groundwater model

• Development
• f

guidelines for effective Groundwater Monitoring System

• Development of Management Information System to store,

review and analyze time series and spatial data

• Irrigation adoption based on model results for an efficient

planning and management of the groundwater resources

Model Calibration . Groundwater Level

Calibration Period: 1997-2003

INDIA

BMDA GW Well BWDB GW Well IWM GW Well

Model Calibration Groundwater Level

Calibration Period: 1997-2003

INDIA

BMDA GW Well BWDB GW Well IWM GW Well

Observed Simulated

Model Validation Groundwater Level

Validation Period: 2004-2005

INDIA

BMDA GW Well BWDB GW Well IWM GW Well

Simulated Observed

Findings

Thana Area (km2) Available Resource (mm) Useable Resource (mm) Irr Requirement Year: 2005 (mm) Remaining Water (mm) Atrai 284 931 838 399 439 Badalgachi 214 607 546 437 109 Bagha 184 369 332 207 125 Bagmara 363 725 653 422 231 Bholahat 124 696 626 377 249 Charghat 165 343 309 368

• 59

Dhamoirhat 301 296 266 462

• 196

Durgapur 195 734 661 414 247 Godagari 472 231 208 295

• 87

Gomastapur 318 189 170 180

• 10

Mohadebpur 398 305 275 482

• 208

Manda 376 553 498 251 247 Mohonpur 163 619 557 345 212 Nachole 284 405 365 206 159 Naogaon 276 564 508 455 53 Nawabganj 452 913 822 134 688 Niamatpur 449 236 212 290

• 78

Paba 280 542 488 287 201 Patnitala 382 331 298 286 12 Porsha 253 335 302 105 197 Puthia 193 461 415 380 35 Raninagar 258 740 666 521 145 Sapahar 245 510 459 193 266 Shibganj 525 586 527 280 247 Tanore 295 180 162 280

• 118

Conclusions of Case Study

It is beneficial to augment surface water irrigation. Groundwater condition is greatly improved by augmented recharge from surface water irrigation During peak time, groundwater table almost regains to its original positions except some areas such as Tanore Upazilas. This is mainly due to higher abstraction in monsoon period. At the same time, recharge is also less compare to the total abstractions in these areas Present withdrawals of groundwater to fulfill the requirement of Boro in excess

• f potential recharges and available resources have created the tendency of

continuous lowering of groundwater level in some Upazilas. Monitoring of groundwater level in these Upazilas need to be carefully continued for future action

• Major knowledge gaps have been observed on uncertainty in the water

availability under climate change consideration, uncertainty in the upstream withdrawal, occurrence of Arsenic, water utility, natural and environmental water requirements

• Many research has already been conducted on Arsenic occurrence and

possible solutions, there are still considerable gaps in the understanding of release mechanism

• Key areas for high priority research are implications for food safety of

irrigation with Arsenic contaminated water; the horizontal and vertical extent

• f contamination;
• Another major issue is prediction of whether aquifer contamination will

change with time, cost-effective solutions for immediate mitigation and long- term solutions

• The utility of groundwater depends on its quality, the level

from which it must be pumped and its sustainable yield

• Remarkable growth in groundwater use over the last two

decades, both for domestic and irrigation use, implies that important planning considerations may be explored further

• Relationship between water and the natural environment is not

well understood

• The knowledge gaps exist in both national and basin level
• Filling gaps is seen as an essential and integral component to

meet the basin level water scarcity in future

• Groundwater

quality particularly salinity is a major issue in the coastal region as well as in the pilot areas

• An assessment
• f the present

state of ground water salinity has been performed using available secondary source data

GW Salinity, Dry & Wet Period 2011-2012 Depth upto 150, Pilot Area-1

GW Salinity, Dry & Wet Period 2011-2012 Depth upto 150, Pilot Area-2

Database Development

Location of Nest Wells

Concluding Remarks

 As groundwater resource is limited both qualitative and

quantitative monitoring of groundwater is required

 Qualitative monitoring is required to assess whether the

groundwater recharge is adequate or not

 If recharge is less than withdrawal then there will be

chance of groundwater mining which is alarming

 Qualitative monitoring is required to assess whether all

the parameters are within the range or not

 It is recognized that water resources problems cannot be

treated in isolation

 The problems are seldom isolated and their solution

requires a holistic approach to water management that must address different, often conflicting, demands for water

 Problems like wetland protection or the conjunctive use of

surface water and groundwater resources require the integrated management of surface water and groundwater together with the water chemistry and ecology

 Regional model for Surface water is available. But

there is no regional model for groundwater

 Groundwater model for whole Bangladesh is required

for coupling surface water and groundwater model

 This will help predicting future scenario of

groundwater resources