Investigation of Salinity Occurrences in Kumar-Madhumati River of Gopalganj District, Bangladesh

摘要

Salinity increases day by day in new areas of Bangladesh. The objective of the research work was to determine the temporal and spatial status of water salinity condition in Kumar-Modhumoti River in Gopalganj district and to find out the main causes of water salinity in that area. The study also incorporated assessment of the existing surface water and soil salinity status by analyzing secondary data of the study area. It has been observed from the data analysis that although Gopalganj is not a coastal district it is also being affected by salinity in dry seasons. During pre-monsoon (March-April), the conductivity of river water is high and ranges from 3.5 dS/m to 4.0 dS/m. In the post monsoon season (Aug-Sept), the conductivity of river water decreases (0.3-0.4 dS/m). One possible cause of salinity increases were investigated by discharge data analysis of Gorai-Madhumati and Arial Khan, two distributaries of the Ganges. Correlation of river discharge data of Gorai-Madhumati and Salinity data of Madhumati River confirms that salinity level is higher when inflow is below 500m~3/s. The decreased inflow entering the river Gorai-Madhumati and Arial Khan is due to the flow diversion from the Ganges by Farakka Barrage. Salinity is an ever-present threat to crop yields, as it is affecting the soil quality. It is also limiting the uses of surface water, which is essential for supplementary irrigation for crop production. That is agriculture of Gopalganj district is mostly depending upon river water which is now being threatened by increasing salinity. Adaptive measures and remediation of water salinity are urgently needed in this area.