The document discusses the impacts of climate change and increasing food demands on water resources in the Ganges Basin of Bangladesh. It finds that precipitation is projected to increase overall by 2030 and 2050 according to climate models, but spatial and seasonal variability may also increase. This would lead to higher irrigation demands for agriculture. The analysis shows that average water yield and aquifer recharge in the basin will likely increase in the future according to the climate scenarios. However, better infrastructure and groundwater management will still be needed to mitigate impacts. Transboundary water sharing of the Ganges between India and Bangladesh is also discussed, noting issues with implementing the 1996 treaty and morphological changes impacting the river system. Strengthening cooperation through updated agreements and joint

1. Impact of Climate Change, Food
Demands and Trans-boundary
Agreement on Water Resources in the
Ganges Basin in Bangladesh
(G4 Project)
Bharat Sharma, U. Amarasinghe, M. Lal, and P. Saikia
International Water Management Institute
Ganges Basin Development Challenge Reflection
Workshop of the CPWF
Sarina Hotel, Dhaka, Bangladesh;
November 12-13, 2013
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2. Annual Water Balance Components –
Ganges ( 1981- 2010)
2000
1800
1600
1400
1000
800
600
400
200
Year
Precipitation
ETa
Water yield
Rainfall
- 609 to 1796 mm/y
Water yield - 250 to 1300 mm/y
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2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
0
1981
mm
1200

3. Climate Change Scenario
CC data :
Climate data from the GCM, Hadley Centre Coupled
Model, version 3 (HadCM3) was downscaled with PRECIS for
the GRB under A1B Special Report on Emission Scenarios
(SRES) scenarios.
Future projection years : 2030, 2050
To represent the hydrological variables in 2030, the average
values between 2025 and 2035 were taken. The average values
of the hydrological variables between 2045 and 2055 were used
to represent the values in the year 2050.
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4. Areas with increased
and reduced
precipitation in 2030 and
2050 compared to the
baseline
In 2030, precipitation
will be reduced over
47% of the basin area
compared to the
baseline period and this
value will be 36% in
2050
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5. Spatial Distribution of Precipitation, Water
yield, ETa and Snow melt ( baseline)
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6. Spatial Distribution of Precipitation, Water
Yield, ETa and Snow Melt ( 2030)
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7. Spatial Distribution of Precipitation, Water
Yield, ETa and Snow Melt ( 2050)
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8. Implications of the Analysis:
 In the A1B scenario considered in this
study, precipitation is projected to increase.
 This would lead to higher PET and increased ETa in
2030 and 2050 compared to the baseline period.
 For agriculture sector, this could mean a higher
demand for irrigation water. In future, the average
water yield over the GRB will increase by about 172
mm and the average shallow aquifer recharge will
increase by about 27 mm in 2050 compared to the
baseline period.
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9.  This is attributed to the higher precipitation in some parts of the
basin, especially during wet season.
 A1B climate change scenario will have positive effect in terms
of the water availability in the GRB. But with a lot of spatial and
temporal variability within the basin. This implies increase in
extreme events in the basin.
A holistic approach of developing infrastructure to
capture the increased flow in the river, and enhanced
groundwater recharge techniques should be a priority
in the GRB. This will help in mitigating adverse effects
of climate change in the future.
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10. 2. Water for Food in Bangladesh: Outlook to 2030
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11. Composition of daily calorie supply per person in Bangladesh
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12. Actual and forecasts of GDP and calorie supply from various cereal, animal
and other crop products
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13. Change in cropping and irrigation patterns in Bangladesh
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14. Auto Regressive Integrated Moving Average (ARIMA )
models predict:
• Further decline in Aus rice area—to 0.7 Mha by
2020, and 0.2 Mha by 2030,
• No significant changes in Aman rice area. It shall
stabilize between 5.7 to 6.1 Mha, and
• Further increase in Boro rice area-- to 5.7 Mha by 2020
and another 1 Mha by 2030. The predicted increase in
Boro rice area will be significantly more than the
decline in Aus rice area
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15. Area and yield of Aus, Aman and Boro rice in Bangladesh
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16. The ARIMA models predict:
Aus rice yield to increase 2.0% annually between 2010 and
2020; 1.2% annually in the 2020’s; and to reach 2.4 t/ha by
2030.
Aman rice yield to increase 1.8 and 1.1% annually in the next
two decades, and reach 2.8 t/ha by 2030; and
Boro rice yield to increase 1.2 and 1.0% annually in the next
two decades, and reach 4.8 t/ha by 2030.
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17. Variation of yield and WP with total CWU across 23 districts
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18. Implications for Water Demand upto 2030
Time
Season
Area
(Mha)
Total
CWU
(Bm3)
Irrigated
Total
Total
production
(Mt)
Water
productivity
(Kg/m3)
Savings of irrigation CWU (Bm3) by
only meeting the rice demand1
WP growth scenarios2
Irrigation
0%
5%
10%
0.0
4.8
0.0
1.9
0.40
-
-
-
5.6
0.6
30.7
0.0
12.5
0.41
-
-
-
4.7
4.5
27.5
16.5
18.3
0.67
-
-
-
Total
11.4
5.1
63.0
16.5
32.8
0.52
-
-
-
Aus
0.7
0.0
3.2
0.0
1.5
0.47
-
-
-
Aman
5.7
0.0
30.8
0.0
14.1
0.46
-
-
-
Boro
5.7
5.7
33.9
20.9
24.6
0.73
2.60
2.74
2.89
Total
12.1
5.7
67.9
20.9
40.2
0.59
-
-
-
Aus
0.2
0.0
1.1
0.0
0.6
0.53
-
-
-
Aman
5.7
0.0
30.8
0.0
15.9
0.52
-
-
-
Boro
6.7
6.7
39.9
24.5
32.1
0.81
6.08
6.40
6.76
Total
2030
1.1
Boro
2020
Aus
Aman
2010
12.6
6.7
71.7
24.5
48.6
0.68
-
-
-
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19. 3. Indo-Bangladesh trans-boundary river
basin cooperation : A Policy Analysis
• Identify the current challenges in Indo-Bangladesh
Ganges River water sharing and management.
• Review the negotiation history and implementation
of the 30-years Indo-Bangladesh Ganges water
sharing treaty signed in 1996.
• To explore and recommend avenues for
cooperation over Ganges not just for water sharing
but also a basin-wide development approach.
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20. The 1996 Ganges Water Sharing Treaty
The 1996 treaty provided the provisions for water sharing of Ganges at the
Farakka border during dry seasons, operational between January 1 and
May 31 each year. Under the treaty an arrangement/water sharing formula
was reached between the two countries on the amount of water transferred from
Farakka into the Padma during the lean season.
Water available at Share of India
Farakka
Share of
Bangladesh
70,000 cusec or
less
50%
50%
70,000-75,000
cusec
Residual flow
35,000 cusec
40,000 cusec
Residual flow
Source: (Salman and Uprety, 2002).
Greater than
75,000 cusec
11/17/2013
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21. Study Findings
 Inadequate implementation of the 1996 Ganges Water
Treaty.
 The 1996 water arrangement is based on the average flow observed (1949-73)
which is 12105.4 cumecs and the annual discharge is 382 BCM. There have
been considerable changes and variation in the flow of water at Farakka after
1996.
 Morphological Changes of the Ganges River system has
been noticed which will pose serious threats to the 1996
water sharing arrangement.
 The rapid change in the Ganges system and the decrease in the dry season
freshwater flow at Farakka barrage is creating a stress in the Indo-Bangladesh
cooperation.
 Changing course of the Ganges and the threat of the river outflowing the Farakka
Barrage.
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22.  Similar concerns noticed in both India and Bangladesh
over the low dry season freshwater flow in the Ganges:
 the Bhagirathi-Hooghly river system in West Bengal and Gorai river system in
Bangladesh.
 Gorai remains dry during lean season.
 Demographic changes in the GDA of West Bengal and Bangladesh has been
noticed.
 Increasing usages of water in the upstream is also affecting the flow of freshwater
at the Farakka point.
 Increasing siltation and changing course of the river channel has also resulted in
erosion of vast tracts of land around Farakka.
 River bed erosion along the Bhagirathi-Hooghly River in West Bengal and
Ganges/Padma in Bangladesh is noticed.
 Reduced freshwater flow also resulting in accumulation of sedimentation.
 Small Rivers and Distributaries along the Lower Ganges Basin is getting dried and
disconnected from the main rivers.
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23. Map showing the Gorai River
11/17/2013
Source: World Bank
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24. Map Showing the Farakka Barrage and Feeder Canal
Source: Kolkata Port Trust
11/17/2013
Map Showing the Feeder canal and Bhagirathi river
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25.  The increasing sedimentation, loose texture of the soil and the varying
discharge from the Farakka barrage into the Bhagirathi has led to a
meander bend of the river channel.
Bishnupur-Charchakundi cut-off
Shankhapur-Moyapur cut-off
Source: Hydraulic Department, Kolkata Port Trust
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26.  The reduced freshwater flow along the BhagirathiHooghly River causing major threats for the navigability
of the Kolkata port.
 The minimum flow of 40,000 cusec, required for the navigability of the Kolkata port has not
been met( as mentioned by authorities of Kolkata Port Trust)
 Analysis shows that the most benefited area from the water diverted from the barrage is the
feeder canal area.
 Navigational routes in Bangladesh(mostly the
distributaries of Ganges) suffers from low flow of Ganges
during dry season causing serious threat to its inland
waterways.
 The low flow of freshwater has resulted in accumulation of sediments on river bed which has
reduced the depth required for navigation of bigger vessels and ships. The country mostly
dependent on its inland waterways for trade and transportation is under serious threat.
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27. Joint River Commission(JRC) must be strengthened
• Joint projects and research studies should
be conducted under a joint team
consisting of technical and policy experts
from both the riparian states.
Basin Commissions must be set up in each of the
riparian countries supervised by JRC.
• Meet an agreement towards the
augmentation of flow during lean season.
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28. THANK YOU
b.sharma@cgiar.org
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