Upload
international-water-management-institute-iwmi-cgiar-water-land-and-ecosystems-program
View
182
Download
0
Tags:
Embed Size (px)
DESCRIPTION
By Zahir-ul Haque Khan, Sarafat Hossain Khan, Dr. M. Shah Alam Khan, Farhana Akter Kamal, Nasim Al Azad Khan Revitalizing the Ganges Coastal Zone Conference 21-23 October 2014, Dhaka, Bangladesh http://waterandfood.org/ganges-conference/
Citation preview
Zahir-‐ul Haque Khan Sarafat Hossain Khan Dr. M. Shah Alam Khan Farhana Akter Kamal Nasim Al Azad Khan
Current surface water resources of the Ganges coastal zone of Bangladesh
Map of Coastal Zone of Bangladesh
Coastal Polders
• PopulaGon 38.35 million (BBS,2011 census),26% of total populaGon
• Total area 47,201 km2, 946 people/km2
• 139 polders, 5107 km embankment
• 1.2 mill. Ha, flood and salinity protected
Study Area:
Ganges Dependent Area in Bangladesh
Coastal Divisions: Barisal: Patuakhali, Barguna Khulna: Khulna & Satkhira districts
Project Target Area: Coastal Zone of the Ganges basin in Bangladesh except the Sundarbans
Polders: 3 (Satkhira), 30 (Khulna), 43-‐2F (Patuakhali)
Polder-‐3 High Salinity
Polder-‐30 Medium Salinity
Polder-‐43/2F Low Salinity
Coastal Zone of the Ganges Basin in Bangladesh
Study Area
1. Hisna ~ Matabhanga ~Betna ~ Kholpetua
2. Kobadak ~ Sibsa
3. Bhairab ~ Rupsa ~ Pussur
4. Gorai ~ Nabagonga ~ Atai ~ Rupsa ~ Pussur
6. Gorai ~ Madhumati ~ Baleswar
5. Gorai ~ Rupsa ~ sholmari ~ Sibsa
7. Arial Khan ~ Baleswar
8. Arial Khan ~ Biskhali
9. Arial Khan ~ Buriswar
River Network South-‐west region
Major river systems in Barisal
Padma~ Arial Kha~ Baleswar Bishkhali Tentulia Buriswar Lower Meghna
Barisal division
Tidal CharacterisGcs
Hyper Tide (>6.0m)
Tidal range >8.0m
Macro Tide ( >4.0m)
Tidal range >4.90m
Tidal range 1.90m
Micro Tide ( <2.0m)
Tidal range 3.0m
Meso Tide ( 2.0~4.0m)
Moving Average(Seasonal VariaGon)
Hironpoint
0.75m 0.70m 1.10m 0.70m
Khepupara
1.00m 1.10m
Char Changa
0.70m 0.70m
Rangadia
Hydrologic Trend Analysis in the Study Area:
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
1930 1940 1950 1960 1970 1980 1990 2000 2010
Discha
rge (m
3/s)
Hardinge Bridge on the Ganges
Max Q Min Q Average Q Linear (Max Q) Linear (Min Q) Linear (Average Q)
• Increasing trend of annual maximum flow
• Decreasing trend of annual minimum flow
Trend Analysis of Upstream River Discharge
Historical Trans-‐boundary Flow in the Ganges Transboundary Flow
Hardinge bridge in dry season
Transboundary Flow
Month
Hardinge Bridge Average flow Year:
1997-‐2011 Year: 2012
Percentage change
December 3454 4375 21% January 2021 2508 19% February 1475 2093 30% March 1029 1199 14% April 989 1188 17%
• Monthly average Ganges flow since the GWT is 14-‐30% less than the 2012 flow
Ganges Water Treaty: 1996
Gorai dredging: 2012
Historical Water Flow staZsZcs at Baruria (Padma River)
Historical Water Flow staZsZcs at Chouduri char (Arial Khan River)
Water Flow at Upstream River
Water Flow in Meghna River
Tidal Water Level Dynamics at Downstream River Tidal dynamics in Baleswer River
Tida
l ran
ge =2.2 m
Tidal dynamics in Tentulia River
Tida
l ran
ge =2.1 m
Available Salinity stations at Barisal division
Salient features: 1. There are 11
salinity stations.
2. Salinity data are available on Meghna, Tentulia, Burisuar, Bishkhali and Baleswar river
Salinity variaZon and Flow availability : Polder 43/2F
Rabi (Boro) Kharif-‐2 (T. Aman) Kharif-‐1 (Aus)
2 PPT
Salinity and Available flow in Payra River
Water available for irrigaGon
Salinity variaZon and Flow availability : Polder 30
Rabi (Boro) Kharif-‐2(T. Aman) Kharif-‐1(Aus)
2 PPT
Salinity and Available flow in Kazibacha River
Water available for irrigaGon
Salinity variaZon : Polder 03
2 PPT
Rabi (Boro) Kharif-‐2 (T. Aman) Kharif-‐1(Aus)
Salinity in IchamoG River
Plenty of water available but cannot be used for irrigaGon due to high salinity
Polder-‐3: Water Management (Drainage and Flushing)
q Land use has changed over the years q Shrimp culture has been introduced q Huge number (133 pipes and 27 private regulators)
of informal structures have been built for flushing brackish water into the polder
q Present drainage system needs to be revisited to meet the demand of flushing brackish water
q 18 new formal structures and improved canal system can meet the demand of flushing brackish water
Benefits: q If properly managed, brackish
water can be considered as a resource, can be used for high-‐income aquaculture without jeopardizing ‘aman’ rice
q Opportunity for crop diversificaGon
Polder-‐3: Water Management (Drainage and Flushing)
SpaZal and Seasonal VariaZon of Salinity in the Coastal Ganges in Bangladesh
Gorai Flow
Khulna
Salinity Flow
Monthly Salinity variaZon with upstream freshwater flow
May, 2012 Base Year: 2012
KHULNA
BARISAL
Level (mPWD) Area below %
0.60 15 1.00 61 1.20 80 1.60 95 1.80 98 2.00 99
Digital ElevaZon Model
Average water level 1.0 m
Lower-‐Shalta river
0 20 40 60 80 100
0
0.5
1
1.5
2
2.5
3
3.5
4
0 10 20 30 40 50 60
Area (Percent)
Land
level (mPW
D)
Area (sqkm)
Area-‐ElevaGon curve
Polder-‐30: Opportunity for Gravity Drainage
Average water level 1.3 m
Kazibacha river
Maximum water level 2.4 m
Minimum water level 0.0 m
THANK YOU