SPATIO-TEMPORAL AVAILABILITY OF EXPLOITABLE WATER RESOURCES FOR EFFICIENT USES IN BANGLADESH

Abstract

Bangladesh, a low-lying riparian country situated within the Ganges Brahmaputra-Meghna Basin, comprises 7% of the total GBM catchment area. The country experiences abundant rainfall during the wet season; however, it encounters low rainfall and subsequent water scarcity in the dry season. Such an uneven distribution of water resources both spatially and temporally results pressure on the resource base. For an efficient management of the resource, the study aims to formulate an effective monthly water conservation strategy. The study estimated water demands across various sectors in Bangladesh, including domestic, industrial, irrigation, and environmental, while contrasting these with supply sources such as surface runoff, groundwater recharge, and transboundary inflows. The total annual water demand was calculated to be 1,017 BCM, while the renewable water availability amounted to 1,138 BCM, indicating no yearly water deficit. Nevertheless, the country-wide seasonal analysis indicated a distinct scenario. During the dry season, a deficit of 8 BCM was observed, whereas the other three seasons had a surplus of water. Analyses of individual basins revealed that all basins experienced water shortages throughout the dry season. Both the Ganges and Southeastern basins additionally faced deficits during the pre-monsoon, while the Meghna basin suffered even in the post monsoon. To address the seasonal difference in water balance, the surplus water was evaluated for its potential monthly storage utilizing the mass curve method. The Storage to Allocation Ratios (SAR) were calculated as 0.345 for the Brahmaputra, 0.313 for the Meghna, 0.245 for the Ganges, and 0.077 for the Southeastern Basin, thereby highlighting the potential for the efficient utilization of available water resources. This methodology can be reproduced for any changes in future demand and supply to establish a monthly water conservation strategy.