Spatial and Temporal Variation of Groundwater Salinity in Barisal and Khulna division of Bangladesh

Abstract

Bangladesh is an agricultural country. Food production of Bangladesh depends on water. Two coastal divisions Barisal and Khulna were surplus in food production. But due to natural hazards the production is decreasing day by day. Salinity causes unfavourable environment and hydrological situation that restrict normal crop production throughout the year. One of the most severe natural calamities is the saline water intrusion. The saline water intrusion is now a major concern for the food security of Bangladesh. The variation of salinity concentration with depth is significant as shallow aquifer has low concentration and the deeper part of the coastal aquifer is highly affected by saline water intrusion. To find salinity concentration at different depth below surface level and to find the present status of ground water salinity are major objectives of the project. In many places of the study area the salinity concentration at 30 meter depth is between 3227 µS/cm to 11830 µS/cm. In monsoon the salinity concentration decreases and increases in dry season. The saline affected area of south western part was more or less 3256836 hactares in last December of 2010. For spatial distribution in the upper shallow aquifer the salinity concentration was low in comparison with the lower shallow aquifer. The salinity aerial extent was also larger in comparison with the upper shallow aquifer. The ground water saline concentration was higher in the months March, April, and May as compared with other months. At 30 meter depth Jessore, Satkhira, Khulna, Bagerhat, Pirojpur, Jhalokati and Bhola are most affected area but at 55 meter depth the affected area mainly the coastal districts (Satkhira, Bagerhat, Pirojpur and Bhola). The worse situation of ground water is in Jhalokati and Satkhira where the all ground water at 30, 45 and 55 meter are harmful for crop cultivation. More research and time series data are required for finding out the effect of tide on the salinity concentration of ground water.