Quantifying monthly water balance to estimate water deficit in Mayurakshi River basin of Eastern India

Abstract

Recorded seasonal variation and uneven distribution of rainfall is one of the major issues to the agrarian society and the domestic water users today. For strategic planning of water use, scientific estimation of water balance in different spatio-temporal scale is necessary. For this, the present paper intends to investigate monthly and annual water balance state of Mayurakshi River basin (including 45 sub-basins) using precipitation (P), runoff (Q), evapotranspiration (ET) and recharge/soil moisture. P, Q, ET, respectively, vary from 1625.97 mm to 2037.93 mm, 182.19 mm to 1503.15 mm and 1050 mm to 1500 mm for the entire basin. The monthly pattern shows significant variation attributed to strong seasonality of P and temperature (T). Monsoon months recorded heavy maximum P, Q and actual ET and on the other hand, all these are very poor during pre-monsoon season. Groundwater recharge annually differs spatially, but annual average recharge is 307mmwith main contribution in monsoon months. Water deficit condition prevails in pre-monsoon season; strong groundwater lowering and drying of top soil are some explicit evidences of the same. This seasonal water scarcity withstands against multi-cropping strategies of the agrarian communities. To cope with this emerging situation, pressure on groundwater is mounting but it is the fact that this resource is also highly limited and precious. Quantification of monthly water balance and water deficit will be inputs to the strategy development for sustainable water resource management.