Road to Sustainable Arsenic Road to Sustainable Arsenic Management in Bangladesh: The Management in Bangladesh: The
Deep Aquifer IssuesDeep Aquifer Issues
K M Ahmed, G Howard, R Ogata & I HuqK M Ahmed, G Howard, R Ogata & I Huq
DU/DFID/JICA/DPHEDU/DFID/JICA/DPHEDhaka 1000, BangladeshDhaka 1000, Bangladesh
[email protected]@univdhaka.edu
Presentation OutlinePresentation Outline
IntroductionIntroduction Deep Aquifer as a Source of Safe WaterDeep Aquifer as a Source of Safe Water Deep Aquifer DefinitionsDeep Aquifer Definitions Development of Deep Aquifer DatabaseDevelopment of Deep Aquifer Database Deep Aquifer MappingDeep Aquifer Mapping Water Quality IssuesWater Quality Issues Current Development StrategyCurrent Development Strategy ConclusionsConclusions RecommendationsRecommendations
Number of Water Points Installed by DPHENumber of Water Points Installed by DPHE
1076792
2048123835 771
0
200000
400000
600000
800000
1000000
1200000
Num
ber
Ope
ratio
nal
in J
une
2007
STW DTW SW RWH
Type of Waater Source
Status of Arsenic in WellsStatus of Arsenic in Wells
10
19
9
6
29
4
1
23
0
12
0
5
10
15
20
25
30
% E
xcee
ding
50
ppb
Dha Chi Syl Bar Far Raj Ran Khu CHT BAN
DPHE Region
Proportion of Shallow & Deep WellsProportion of Shallow & Deep Wells
0
50000
100000
150000
200000
250000
300000No
of W
ells
Dha Chi Syl Bar Far Raj Ran Khu CHT
DPHE Region
Tot S Tot D Tot W
0
20
40
60
80
100
% o
f Wel
l s
Dha Chi Syl Bar Far Raj Ran Khu CHT BAN
DPHE Region
% S % D
Mitigation ImplementedMitigation Implemented
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
Num
ber I
nsta
lled
DW PSF RWH DTW AIRP PWSS SST DSP
Mitigation Options
0
10
20
30
40
50
60
70
% o
f Ins
talle
d O
ptio
ns
DW PSF RWH DTW AIRP PWSS SST DSP
Mitigation Options
0102030405060708090
% F
unct
iona
l
DW PSF RWH DTW AIRP PWSS SST
Option
Number of Options % of Total Number of Options
% of Functional Options
(Data Source: APSU)
Mitigation by sources of waterMitigation by sources of water
96%
1% 3%
GW SW RWH
14%
2%0%
84%
ARP&P DW SST DTW
Sources of Water
Mitigation Option
Relative Risks of Various SourcesRelative Risks of Various Sources
(Howard et al., 2006)
Aqui-fer Units
UNDP, 1982 Aggarwal et al., 2000
BGS& DPHE, 2001
JICA, 2002 GWTF, 2002
1 Upper/Composite Aquifer
1st Aquifer Upper Shallow Aquifer
Upper Aquifer
Upper Holocene Aquifer
2 Main Aquifer 2nd Aquifer
Lower Shallow Aquifer
Mid Aquifer Middle Holocene Aquifer
3 Deep Aquifer
3rd Aquifer
Deep Aquifer
Deep Aquifer
Late Pleistocene-Holocene Aquifer
4 Plio-Pleistocene Aquifer
Lateral Variations in AquifersLateral Variations in Aquifers
(Ahmed, 2003)
Alam et al., 1990)
Deep Aquifer Definitions -1Deep Aquifer Definitions -1
Morton and Khan (1979) describe the deep Morton and Khan (1979) describe the deep aquifer from Barisal and Patukhali districts as the aquifer from Barisal and Patukhali districts as the one that occurs at depths ranging from 238 to one that occurs at depths ranging from 238 to 328m 328m
Jones (1985) describes the saturated deep Jones (1985) describes the saturated deep Tertiary sequences, identified from the electrical Tertiary sequences, identified from the electrical logs of oil and gas wells at the depths of 1000 to logs of oil and gas wells at the depths of 1000 to 3000m, as the deep confined aquifers.3000m, as the deep confined aquifers.
MPO (1986) based on the information of Jones MPO (1986) based on the information of Jones (1985) proposed the term Lower Aquifer (1985) proposed the term Lower Aquifer Sequence for the aquifers occurring underneath Sequence for the aquifers occurring underneath the main aquifer of UNDP, 1982. the main aquifer of UNDP, 1982.
Deep Aquifer Definitions -2Deep Aquifer Definitions -2 Khan (1991) defined deep aquifer as “those aquifers Khan (1991) defined deep aquifer as “those aquifers
whose waters have no access vertically upward or whose waters have no access vertically upward or downward but flow very slowly along the dips and slopes downward but flow very slowly along the dips and slopes of the aquifer. The depths of the deep aquifers containing of the aquifer. The depths of the deep aquifers containing useable water range from 600 feet to 3000 feet on the useable water range from 600 feet to 3000 feet on the Dinajpur platform and 800 feet to 5000 feet in the basin”. Dinajpur platform and 800 feet to 5000 feet in the basin”.
DPHE/UNICEF/WB (2002): It was agreed at the meeting DPHE/UNICEF/WB (2002): It was agreed at the meeting that deep aquifer should not be defined in terms of depth that deep aquifer should not be defined in terms of depth where the depth would depend on local/regional where the depth would depend on local/regional hydrogeological conditions. There should be an aquitard hydrogeological conditions. There should be an aquitard or aquiclude separating the shallow and deep aquifers.or aquiclude separating the shallow and deep aquifers.
DPHE & BGS (2001) considered the red brown Dupi Tila DPHE & BGS (2001) considered the red brown Dupi Tila of the Chandina area, and Barind Madhupur Tracts and of the Chandina area, and Barind Madhupur Tracts and grey sub-150m deep aquifers composed of cyclic, grey sub-150m deep aquifers composed of cyclic, vertically stacked aquifers in the subsiding delta as the vertically stacked aquifers in the subsiding delta as the deep aquifer.deep aquifer.
Deep Aquifer Definitions -3Deep Aquifer Definitions -3 JICA (2002) hydrogeologically defined deep aquifer JICA (2002) hydrogeologically defined deep aquifer
as consisting of D and E formations of Pleistocene as consisting of D and E formations of Pleistocene age at depths of 160 to 220m in their study area in age at depths of 160 to 220m in their study area in Jessore, Jhenaidah and Chaudanga districts of SW Jessore, Jhenaidah and Chaudanga districts of SW Bangladesh. Bangladesh.
Ravencroft (2003) defined deep aquifers as those Ravencroft (2003) defined deep aquifers as those accessible to current water well technology (<350m) accessible to current water well technology (<350m) and already developed by hand tubewells and locally and already developed by hand tubewells and locally by production tubewells (e.g. Khulna). He termed the by production tubewells (e.g. Khulna). He termed the deep aquifers of Jones and Khan as “super-deep” deep aquifers of Jones and Khan as “super-deep” aquifers and commented that it was unlikely that their aquifers and commented that it was unlikely that their exploitation would be economically viable for the exploitation would be economically viable for the foreseeable future. foreseeable future.
Zheng et al. (2005) defined shallow (<28m) and deep Zheng et al. (2005) defined shallow (<28m) and deep (40-90m) aquifers in a local case study based on (40-90m) aquifers in a local case study based on hydrogeological and hydrogeochemical contrasts.hydrogeological and hydrogeochemical contrasts.
Deep Aquifer Definitions –approachesDeep Aquifer Definitions –approaches
From the various definitions it is evident that deep aquifer From the various definitions it is evident that deep aquifer can be defined in a number of ways such as:can be defined in a number of ways such as: By depth: 150m as the boundary as adopted in the By depth: 150m as the boundary as adopted in the
BGS & DPHE (2001).BGS & DPHE (2001). Hydrostratigraphically: presence of a thick low Hydrostratigraphically: presence of a thick low
permeability layer, i.e. silt and clay layer in between the permeability layer, i.e. silt and clay layer in between the shallow and deep high permeability layers (aquifers), shallow and deep high permeability layers (aquifers), i.e. sand and gravel layersi.e. sand and gravel layers
Hydraulically: an observable head difference between Hydraulically: an observable head difference between the two aquifers the two aquifers
Hydrogeochemically: possesses groundwater with Hydrogeochemically: possesses groundwater with distinctly different hydrogeochemical faciesdistinctly different hydrogeochemical facies
Geologically: belongs to two different geological units, Geologically: belongs to two different geological units, e.g. Holocene and Pleistocene.e.g. Holocene and Pleistocene.
Deep Aquifer Definitions -ProposedDeep Aquifer Definitions -Proposed
Deeper Holocene/Late Pleistocene-Holocene Deeper Holocene/Late Pleistocene-Holocene aquifer separated by one or more sufficiently thick aquifer separated by one or more sufficiently thick (~10m) clay/silty clay aquitard or Pleistocene Dupi (~10m) clay/silty clay aquitard or Pleistocene Dupi Tila aquifer overlain by Pleistocene Clay or Tila aquifer overlain by Pleistocene Clay or separated by Holocene clay from the alluvial separated by Holocene clay from the alluvial aquifer. aquifer.
In the coastal region the Pliocene Tipam In the coastal region the Pliocene Tipam formation may also serve as the deep aquifer. formation may also serve as the deep aquifer.
It is proposed that there should not be a fixed It is proposed that there should not be a fixed depth attached to the definition of deep aquifer. depth attached to the definition of deep aquifer.
DEEP AQUIFER MAPPINGDEEP AQUIFER MAPPING
Distribution of Data PointsDistribution of Data Points
Chandpur Sadar UpazilaChandpur Sadar Upazila
Shallow Aquifer
Deep Aquifer
Satkhira Borelog Satkhira Borelog LocationLocation
Satkhira District ModelingSatkhira District Modeling
Data Coverage in Southern BangladeshData Coverage in Southern Bangladesh
Kushtia-Kushtia-Jessore-Khulna Jessore-Khulna
Regional Regional MappingMapping
Hydrostratigraphy of the Kushtia-Jessore-Khulna Region Hydrostratigraphy of the Kushtia-Jessore-Khulna Region
Khulna Region Hydrostratigraphic ModelKhulna Region Hydrostratigraphic Model
Comilla-Noakahli Comilla-Noakahli Regional Regional MappingMapping
NS Hydrostratigraphic SectionsNS Hydrostratigraphic Sections
EW Hydrostratigrapic Cross SectionsEW Hydrostratigrapic Cross Sections
Comilla-Noakhali Region Hydrostratigraphic ModelComilla-Noakhali Region Hydrostratigraphic Model
Depth to the Aquitard 2 in the Southern RegionDepth to the Aquitard 2 in the Southern Region
Thickness of the AquitardThickness of the Aquitard
Water Quality of the Deep Aquifer - Water Quality of the Deep Aquifer - ArsenicArsenic
Arsenic Data from Arsenic Data from DPHE Zonal LabsDPHE Zonal Labs
0
5
10
15
20
% o
f Sam
ple
DHA (1608) CHI (1724) SYL (293) KHU (1846) BAR (588) TOT (6059)
Division
>0.05 mg/L >0.01 mg/L
Depth Distribution of ArsenicDepth Distribution of Arsenic
0
50
100
150
200
250
300
350
0.00 0.05 0.10 0.15
As concentrations (mg/L)
Scre
en D
epth
(mbg
l)
<150m >150-200m >200-250m >250-300m >300-350m
Iron in Deep Iron in Deep GroundwaterGroundwater
0
10
20
30
40
50
% o
f wel
ls
<0.3 >0.3-1.00 >1.00-5.00 >5.00
Fe concentrations (mg/L)
0
50
100
150
200
250
300
350
400
0.00 3.00 6.00 9.00 12.00 15.00
Fe concentrations (mg/L)
Scre
en d
epth
(mbg
l)
<150m >150-200m >200-250m >250-300m >300m
Chloride in Deep Chloride in Deep GroundwaterGroundwater
0
20
40
60
80
100
% s
ampl
es
<600 >600-1000 >1000
Cl concentrations (mg/L)
0
50
100
150
200
250
300
350
400
0 1000 2000 3000 4000 5000 6000
Cl concentrations (mg/L)
Scre
en d
epth
(mbg
l)
<150m >150-200m >200-250m >250-300m >300m
Manganese in Deep Manganese in Deep GroundwaterGroundwater
0
20
40
60
80
100
% s
ampl
es
~0.1 >0.1-0.4 >0.4
Mn concentrations (mg/L)
0
50
100
150
200
250
300
350
0.00 0.50 1.00 1.50 2.00 2.50
Mn concentrations (mg/L)
Scre
en d
epth
(mbg
l)
<150m >150-200m >200-250m >250-300m >300m
Mitigation StrategyMitigation Strategy
National Arsenic Policy 2004National Arsenic Policy 2004- access to arsenic-safe water for drinking and - access to arsenic-safe water for drinking and cooking will be ensured;cooking will be ensured;- all patients will be managed effectively;- all patients will be managed effectively;- public awareness will be raised about impact of - public awareness will be raised about impact of arsenic contaminated water;arsenic contaminated water;- capacity will be built at all levels for implementation - capacity will be built at all levels for implementation of mitigation options, surveillance and monitoring of of mitigation options, surveillance and monitoring of water quality and diagnosis and management of water quality and diagnosis and management of patients;patients;- impact of arsenic on agriculture will be assessed. - impact of arsenic on agriculture will be assessed.
Inter-ministerial Committee on Deep AquiferInter-ministerial Committee on Deep Aquifer
A committee has been constituted at the ministry of Local A committee has been constituted at the ministry of Local GovernmentGovernment
Representatives of Universities, Research Institutes and Representatives of Universities, Research Institutes and Government DepartmentsGovernment Departments
Approval has to obtained from this Committee for Approval has to obtained from this Committee for installing DTW by any GOB Departmentinstalling DTW by any GOB Department
The Committee Reports to the National Committee of The Committee Reports to the National Committee of ExpertExpert
Has given approval to applications made by BAMWSP Has given approval to applications made by BAMWSP and GOB5 projects of DPHEand GOB5 projects of DPHE
Ineffective for sometime now though DTW installation Ineffective for sometime now though DTW installation going on in many areas of the country!going on in many areas of the country!
ConclusionsConclusions There is not enough data to prepare There is not enough data to prepare
national scale deep aquifer mapnational scale deep aquifer map There are inconsistencies in borelogs There are inconsistencies in borelogs
availableavailable First step towards compilation of a deep First step towards compilation of a deep
aquifer databaseaquifer database RockWorks can be used for preparing RockWorks can be used for preparing
sections, fence diagrams and sections, fence diagrams and hydrostratigraphic modelshydrostratigraphic models
Good beginning of converting piles of Good beginning of converting piles of paper data into digital database and paper data into digital database and preparing mapspreparing maps
RecommendationsRecommendations Recording and Preservation of Lithologs and well Recording and Preservation of Lithologs and well
construction at DPHE and all other agencies using construction at DPHE and all other agencies using a Standard Format should be made mandatorya Standard Format should be made mandatory
A comprehensive Deep Aquifer Investigation A comprehensive Deep Aquifer Investigation including WQ study should be undertaken including WQ study should be undertaken urgentlyurgently
Wise use of deep groundwater should be Wise use of deep groundwater should be advocated until proper assessment has been advocated until proper assessment has been mademade
Deep Groundwater should be used only for Deep Groundwater should be used only for potable usespotable uses
Care should be taken in installing DTWs to avoid Care should be taken in installing DTWs to avoid cross contaminationcross contamination
Monitoring Network should be designed and Monitoring Network should be designed and installed for resource and quality surveillanceinstalled for resource and quality surveillance
DhanyabadThank You All
