Conference on International Agricultural Research for Development Estimation of Potential recharge and groundwater resources assessment - A case

The study area consists of eight upazilas of north-west region of Bangladesh. This is one of the driest parts of Bangladesh, normally less rain from November to April. The study area has been irrigated using about 2100 Deep Tubewells. It covers only about 80% of the total cultivable area. The remaining 20% area has been planned to cover by installation of additional Deep Tubewell under Bangladesh Multipurpose Development Authority (BMDA). To ensure the long term sustainability, the consequences of the groundwater development in the region need to be analyzed. This study tried to explore the appropriate modelling technique to increase agricultural production through sustainable utilisation of available water resources using Visual MODFLOW. From the study it can be seen that groundwater resources are inadequate in Raninagar, Durgapur and Puthia upazilas of the study area. Present withdrawals of groundwater to fulfil the requirement of Boro in excess of actual recharges and available resources have created the tendency of continuous lowering of groundwater level in these 3 upazilas. The deficit indicates a non-sustainable situation with increasing draw down. 80% coverage of Boro for all cultivable land of upazilas will incur an additional draw down, for which, quite a large number of shallow tubewells need to be replaced by Deep Tubewell. Monitoring of groundwater level in these upazilas need to be carefully continued for future action. Vertical percolation of rainwater is the main source of groundwater; increasing duration of percolation time and area by construction of water control structures on the rivers and Kharies will increase groundwater recharge. There is a possibility of increase of groundwater recharge by conservation of surface water in rivers and kharies in the post monsoon by retention structures. Conjunctive use of surface water —groundwater irrigation should be promoted and a conjunctive water allocation plan must be established.