Fulco Ludwig: salt intrusion and water supply
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Transcript of Fulco Ludwig: salt intrusion and water supply
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Climate change impacts on Salt water intrusion in Coastal Bangladesh
Dr. Fulco Ludwig Earth System Science Group
Wageningen University 27 January 2016
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Ganges
Brahmaputra
Meghna
GBM BASINS The GBM Basins drain 1.72 Mi km2 area 93% of the area outside Bangladesh 75-80% of flow in 5 months of monsoon
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Saltwater intrusion is caused by a combination of sea level rise and reduction of dry season river flows
Dis
char
ge
(m2/
s)
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Water Supply for the city of Khulna
§ Khulna is the 3rd largest of Bangladesh § Local water is saline during the dry season § Only deep groundwater can be used for drinking water § Large parts of the Khulna residents drink saline water
during part of the year § ADB and Japanese gvt wanted to invest 250 million US$
in a new drinking water plant § The question is where to build to plant and where to get
the water from and will this be affected by climate change
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Salt intrusion in May in Southwest Bangladesh
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Modelling framework to assess future salt intrusion
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Future Sea Level Rise – end of 21st Century – From IPCC AR5
IPCC 2013
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0 SLR 32 cm SLR 88 cm SLR
Impact of SLR on Salinity Intrusion
Hiron Point
Bay of Bengal
Mongla
Khulna
Movement of 5 ppt Salinity line
Source: IWM
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Climate change impact on flow of the Ganges under 2 degree warming
-‐60%
-‐40%
-‐20%
0%
20%
40%
60%
80%
100%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Change in Ganges Flow
Com
pared to
1985
-‐200
5 (%
)
CNRM RCP8.5 (2035-‐2055) SMHI RCP8.5 (2029-‐2049)
Reduction in flow in May when salt intrusion is highest
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Climate change impact on salt water intrusion
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Salinity
(PPT)
Atharobanki R: Avge. Salinity in RCP 8.5 Scenario RCP 8.5 (2029-‐2049) Base (1985-‐2005) RCP 8.5 + Gorai Dredging2 degree warming Gorai dreding + 2 degree warming
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Where to develop the drinking water plant
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Conclusions
§ Combined reduced dry season river flows and sea level rise result in large scale increases in salt water intrusion
§ Salt intrusion is likely to increase in the future in Southwest Bangladesh unless dramatic infrastructure measures are taken
§ Water intake for drinking water supply near Khulna is not suitable due to increasing salt water intrusion
§ This study recommends Mollarhat as intake point due to low salinity
§ In addition a reservoir can be developed