Prospects of Artificial Recharge for Augmentation of the Upper Dupi Tila Aquifer in Dhaka City, Bangladesh Workshop on ACTION RESEARCH ON GROUNDWATER BUFFERING

Prospects of Artificial Recharge for Augmentation of the Upper Dupi Tila Aquifer

in Dhaka City, Bangladesh

Workshop onACTION RESEARCH ON GROUNDWATER BUFFERING IN BANGLADESH

24 February, 2011

Sarmin SultanaDepartment of Geology, University of Dhaka

Presentation Outline

● What is AR & what are the techniques● Why AR in Dhaka city● What is the source of water for AR● Objectives of this study● Results and discussion● Conclusions● On going research

The Megacity Dhaka Needs no introduction

14%

86%

Ground Water Surface Water

Water Demand and Supply

Why AR in Dhaka city

● GW Dependant City● No imported water● Big Gap between supply and Demand● Heavy GW abstraction and well deepening● Rate of water table decline 3.5 m/y● Aquifer dewatering

Uniqueness of Dhaka in terms of GW problem

No GW management !

GW hydrograph of Upper Dupi Tila demonstrates a steady down ward slope.

19801970 1995 2007

Water Table Elevation Contour for dry season as on 2008

Cone of depression

Is going Deep a sustainable Solution?

http://en.wikipedia.org/wiki/File:Dhaka_skyline1.jpg

0

100

200

300

J an-77 J an-77 Feb-77 Mar-77 Apr-77May-77May-77 J un-77 J ul-77 J ul-77 Aug-77 Sep-77 Sep-77 Oct-77 Nov-77 Nov-77 Dec-77

7-D

ay r

ain

fall

(mm

)

-3

-2

-1

0

1

2

3

4

GW

L (

m,P

WD

)

7-Day rainfall

GWL

0

50

100

150

200

250

300

J an-93 J an-93 Feb-93 Mar-93 Mar-93 Apr-93 May-93 May-93 J un-93 J ul-93 Aug-93 Aug-93 Sep-93 Oct-93 Oct-93 Nov-93 Dec-93 Dec-93

7-D

ay ra

infa

ll (m

m)

-15

-12

-9

-6

GW

L (m

,PW

D)

7-Day rainfall

GWL

GW hydrographs and corresponding 7-day rainfall are plotted for 1977 and 1993.

Mirpur (GT-2648010)

Dhaka station (R009}

Rainfall in Dhaka

Objectives

● To estimate the current open space available for natural recharge to take place;

● To delineate potential zones for implementing site-specific artificial-recharge techniques using GIS analysis; and

● To assess suitability and applicability of Artificial Recharge in Dhaka.

39.9943.93Natural water body (periphery)

22.224.39Open Area (vegetation reflection)

4.044.44Water Body (inside the city)

100109.84Total

32.4335.62Low-lying area (depression)

1.331.46Open Area(sand reflection)

Area in %Area in sq.kmClass Name




100109.84Total




Are

a in

%

Bar Diagram of Recharge Area Classes





Natural Recharge Area Map





































Status of the pond immediate after rain

Status of the pond after 3 days from raining

Infiltration Test at the pond of Institute of Fine Arts

0 - 10

& open area available

Zone 1

Clay thickness

(m)

Zone

0 - 10


Zone 1

Clay thickness

(m)

Zone

Rules for selecting prospectivezones of artificial recharge

Potential Zones

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

15 - 25 Zone 3

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

15 - 25 Zone 3

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

25 - 50 Zone 4

15 - 25 Zone 3

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

25 - 50 Zone 4

15 - 25 Zone 3

10 - 15

near water bodies

Zone 2

0 - 10


Zone 1

Clay thickness

(m)

Zone

City area (sq. km)

Avg. annual rainfall

(m)

Total volume rainfall (M L)

No of total concrete house available for rain water collection

Each roof area (sq, m)

Total roof area (sq.

km)

Yearly total volume of rainwater

(ML)

Daily Total Volume Of Rainwater (MLD)

370 2 740,000 6,78,000* 110 74.58 149160 408.65

R 1 R 2 R 3 R4 R5 Total

175 47 21 15 6 264

Abandoned well

Production well

Volume of Rainwater Available in Dhaka city (Sources: BBS)

Number of abandoned wells of DWASA.

Other OptionsDredging and re-excavation of khalsAvoid construction along faultsRiver dredging and Bank filtrationSystematic Clay Mining

Production well

If 30 % of this water can be collected, then more than 100 MLD water will be available to recharge the aquifer artificially.

No of Locatio

ns

Clay thickness

(m)Method

6 10 – 15 Trench pit

6 40 – 50 Injection well

2 3 – 7 Dug well

35 – 15 Lateral trench with

vertical shaft

1 0 – 10 Spreading Technique

220 – 25

Retention pond with well

2 25 – 35 En-echelon Dam

2 15 -30 Check dam

Rules for selecting sites ofdefinite artificial recharge methods

Site Specific Artificial Recharge Technique Map

Dhaka has high potential for Artificial Recharge

THANK YOU

Workshop onACTION RESEARCH ON GROUNDWATER BUFFERING IN BANGLADESH

24 February, 2011

Documents

Prospects of Artificial Recharge for Augmentation of the Upper Dupi Tila Aquifer in Dhaka City, Bangladesh Workshop on ACTION RESEARCH ON GROUNDWATER BUFFERING