Transcript Slide 1

ACTION RESEARCH ON WATER
BUFFERING IN BANGLADESH
SCOPE AND OPTIONS FOR APPLICATION
IN BANGLADESH
Albert Tuinhof – Acacia Water
Dhaka, 24 February 2011
Department of
Public health
Engineering
University of Dhaka
Geology Department
(GROUND)WATER BUFFERING IN
BANGLADESH
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Why is storage important ?
Water buffering: the concept
Technical options
Possibilities in Bangladesh
Examples/tools
Cost and benefits
STORAGE: BETWEEN RESOURCE AND SUPPLY
Resource mgt and water supply
need more integration
Water res. dev. & mgt.
Water supply provision
Source
Abstraction
Storage needed to
bridge gaps in supply
and demand
Treatment
Distribution
Point of use
SOME FIGURES
• Surface water storage per capita
– Ethiopia 43m3
– South Africa 750m3
– North America 6150m3
• Village ponds or domestic rainwater storage could add 2-5
m3 per person per annum
• Each additional 10mm groundwater recharge could add 50100 m3 per person per annum
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WHERE STORAGE IS INADEQUATE
5
WHERE THERE IS STORAGE
The Economist 22 May 2010 :
In semi- arid Gujarat agriculture has grown at an
average of 9.6% since 2000, due to the creation
o f 5 0 0 , 0 0 0 s m a l l p o n d s , d a m s a n d s u c h l i ke
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STORAGE IS BUFFERING
Its not about allocation scarce water but to catch and retain water and extend
the chain of use and reuse as possible within a basin
MANAGING THE WATER BUFFER: THE CONCEPT
Quick scan to assess hydrological,
socio-economic and environmental
conditions and water buffering needs
on basin /catchment level
Selection of appropriate Recharge,
Retention and Reuse) interventions
using tools and valuation techniques
for decision making
Focus on rural water livelihoods but
also for urban ws and productive use
Goal: upscaling (pilot projects) and
integration of buffer management in
IWRM /Basin Water Management
RAIN, SURFACE AND GROUNDWATER
• Local tanks, surface water and subsurface storage (active
use of aquifer) for both water- and food security
• Subsurface storage (MAR) is largest potential in terms of
quantity (m3 ) and quality protection
MAR
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CLASSIFICATION OF 3R SOLUTIONS
Code
A
1
2
4
Rainfall
Recharge/
interception
Surface
recharge
Method
Rain Surface Stream
water runoff flow
infiltration ponds / recharge basins/
percolation
flooding
andtanks
irrigation
ditch, furrow, drains, burrowing, punching
Induced
bank infiltration
infiltration
B
1
C
1
2
3
Point
recharge
D
1
3
5
6
In channel
recharge and
retention
E
1
3
4
5
Run-off and
rainfall
harvesting
deep injection well (ASR, AS-TR)
shallow injection well / recharge shafts
dug well /recharge pits
X
X
X *1)
X *1)
X
gully plugging /small weirs
sand dams /gabions /sub surface dams
recharge dams /percolation tanks/ check
maintaining river beds/stream channel mod
barriers, bunds, trenches
terracing, vegetation strips etc
ponds / reservoirs /checkdams
RW interception + tank/reservoir/cistern
x2)
Reuse
GW
GW
GW
drain/well
/gallery +
pump
X
GW
Well/gallery +
pump
X
GW
GW
GW
Well + pump
GW/M
GW
GW/SW
GW/M
Mainly
Well + pump
X
X
X
x3
X
X
X
X
X
X
X
Retention
X
X
X
M
M
SW
SW
Transpiration
Pump
Pump/tap
x 1) i nfi l tra tion a fter tempory s tora ge a nd pre trea tment (fi l teri ng), ma y a l s o ma ke us e of other s ources l i ke trea ted wa s te wa ter or urba n s tormwa ter run-off
x 2) SW: s urfa ce wa ter, RW: Ra i nwa ter, GW: Groundwa ter ; M:Moi s ture
3R and MAR
MAR:
building infrastructure
and/or modifying the
landscape to intentionally
enhance groundwater
recharge
Recharge enhancement
provides additional storage
POTENTIAL IN BANGLADESH
Tistafan
Sandy deposits
Barind Tract:
Quantity
Madhipur Tract:
Overexploitation
Sylhet: surface
Clay and geology
Flood Plains:
Arsenic
Coastal zone:
Coastal:
Salinity
Salinity
Chittagong Hills:
Difficult Geology
POTENTIAL IN BANGLADESH
Recharge/
interception
Surface
recharge
Induced
infiltration
Point
recharge
Barind
Tract
-
Tista
Fan
+
+
-
bank infiltration
-
+
-
+
-
-
-
deep injection well (ASR, AS-TR)
shallow injection well / recharge shafts
dug well /recharge pits
+
+
-
+
+
+
+
+
+
+
+
+
-
+
+
+
-
gully plugging/ small weirs
+
+
+
-
-
+
-
-
+
+
+
barrier, bunds, trenches etc.
+
+
-
+
-
-
-
RW interception + tank/reservoir/cistern
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Method
infiltration ponds / recharge basins
flooding and irrigation
ditch, furrow, drains, burrowing, punching etc
In channel sand dams /gabions /sub surface dams
recharge and recharge dams /percolation tanks/ check dams
retention maintaining river beds /stream channel
Flood Madhupur
Sylhet
Coastal
X2)
x1)
Depression Plains
Plains
Tract
+
+
+
+
Hill
Tracts
-
modifcations
Run-off and
terracing, nefarim, veg strips etc
rainfall
ponds / reservoirs /checkdams
harvesting
x1): Incl udes Grea ter Dha ka
x2) i ncl udes Cha pa i Na wa bga nj a rea
BANK INFILTRATION:CHAPAI NAWABGANJ
Production wells drilled along the Mohanandan River abstract part of the water from the river.
Simulations with a groundwater model and with a Bank Infiltration Simulator (NASRI) show
that approximately 30% (dry season) to 60% (wet season) of the pumped water (at 30-50 m)
originates from the river with travel times of 5-10 days (wet season) to 30-40 days (dry season).
SAND STORAGE DAMS
Abstraction well
Subsurface storage
- Capital cost : 8,000-12,000 USD
- Annual cost: O&Mand monitoring: 1,000-1500 USD
- Water storage provided: 2,000 m3/rainy season
- Number of users: 20-30 families (100-200 users)
SHALLOW GROUNDWATER INFILTRATION
ACTION RESEARCH ON GROUNDWATER BUFERING IN BANGLADESH , PHASE 2
Infiltration testing
Khulna
Sundarbans
Pilot Study of fresh WR in the coastal belt
(IWACO, UNICEF, 1985)
INFILTRATION TESTING
Fresh water from ponds and roofs can be
injected in the shallow (brachish) aquifer
during monsoon for abstraction during dry
season
2 tests sites are constructed and tested after
the 2010 monsoon
2 new sites will be added for testing during
the 2011 monsoon
A 3D model was made to guide the testing
and to be calibrated for future desings and
upscaling
3R solutions to improve Water Quality and Quantity
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UPSCALING POTENTIAL SHALLOW GW INFILTRATION
IN KHULNA AND SATHKIRA DISTRICT:
Upozila
Population
2006
Area km2
%
affected
Kaliganj
275.000
329
100
Assasuni
268,000
377
100
Syamnagar
337,000
1969
100
Batiaghata
151,000
237
20
Paikgacha
267,000
378
50
Koyra
207,000
1583
100
Dacope
169,000
1050
100
Rampal
192,000
276
80
Mongla
160,000
1502
100
Morrelganj
376,000
439
95
Sarankhola
123,000
Total
825
100
2,526,000
Experiences can also be used to assess and test the
application elsewhere in Bangladesh
SIMULATION MODEL RAINWATER HARVESTING
Station
DHAKA
Coordinates Longitude xxx
Town
Province /District
Country
Country
BANGLADESH
Latitude xxx
Dhaka
Average monthly rainfall
400.0
Bangladesh
350.0
Rainfall data
Period:
1953 1982
Number of years
ny
30
Number months
nm
360
1951
Average annual rainfall (mm)
Fixed input parameters
Leakage losses (%)
L
Run-off coefficient
f
Consumption
Jan
(lit/cap/day)
5
Average rainfall
300.0
250.0
200.0
150.0
100.0
50.0
0.0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Month
5
0.8
Feb
Mar
Apr
5
5
6
May Jun
6
6
Jul Aug Sep
6
6
5
Oct
5
Nov Dec Average
5
5
5.4
Catchment area (m 2) /cons.
Ac
2
Storage capacity (m 3) / cons.
Vc
0.8
Supply Level
Dhaka, Bangladesh, 1953-1982
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
25
49
73
97
121 145 169 193 217 241 265 289 313 337 361
Months
No. of months with Sl<1 :
No. of months with SL=0 :
22
0
Reliability (St): aggregated
supply level over whole period
0.98
Reliabiliy (St) for a range of Ac and Vc
Ac
0.98
2
4
6
8
10
12
0.8
0.98 0.99 1.00 1.00 1.00 1.00
1
1.00 1.00 1.00 1.00 1.00 1.00
Vc 2
1.00 1.00 1.00 1.00 1.00 1.00
3
1.00 1.00 1.00 1.00 1.00 1.00
4
1.00 1.00 1.00 1.00 1.00 1.00
Design parameters of RHS for selected Ac
and Vc which are entered in above graph
Ac
2
Vc
0.8
reliability St
select values for red numbers
A(m 2)
V (m 3)
Param eter
Roof surface (A)
0.98
No.
500
200
250
Tank capacity (V) 25
No. consumers
100
10
40
13
50
ECONOMIC VALUATION OF STORAGE: 3R CBA
OVERVIEW OF COST /BENEFITS OF STORAGE
COST
ITEM
VALUATION
CONSTRUCTION
Incl. design etc
USD
ADDITIONAL COST
Land acquisition
Power supply
USD
SOCIAL/ENV. COST
EIA/SIA / Mitigation
USD - USD/yr
O&M
Incl .monitoring
USD/yr
BENEFITS
ITEM
VALUATION
REDUCED COST OF WATER
Drinking, livestock, rural industry,
small scale irr.
INCR. PRODUCTIVITY
See above: income increase
HOUSEHOLD BENEFITS
Improved health, more time
SOCIAL / COMMUNITY
BENEFITS
Cohesion, security, education
ENVIRONMENTAL BEN.
Biodiversity, vegetation
USD/yr, based on
interviews
Indirect, through
valuation
methods.
EXAMPLES OF MEASURED BENEFITS : INDIA
Kolwan Valley
3 check dams
Population 15,000
Catchment area 80 km2
Satlana Carr
3 check dams/1 percolation pond
Population 4250
Catchment area 20 km2
Location
USBed
Dsbed
Samrapur
Vajapur
Nedardi
Control
total
Village
Bhalgudi
Chikhalgaon
Hadshi village
Nanegaon
Nadgaon
average
agricultural income
(Rs thousand/yr)
before
after
18.00
36.00
10.00
28.00
28.00
35.00
16.00
19.00
15.00
33.00
22.00
23.00
household income
(Rs thousand/yr)
1996
2004
18,000
26,000
20,000
28,000
24,000
30,000
62,000
20,000
20,667
33,200
Thank you