9. Spatio-Seasonal Runoff and Discharge Variability in the Ganga River Basin, India: A Hydrometeorological Perspective

The study focuses to understand spatial and seasonal variability of runoff and discharge across the Ganga River basin. To execute the study runoff and discharge data of 13 stations (5 stations on the Ganga River and other 8 are on the major tributaries) across the river basin had been used. The classification of season: monsoon (June–September), post monsoon (October-December), winter (January-March) and summer (April–May) had been considered as the base of seasonal variability analysis. The average runoff distribution reflectall major tributaries of the Ganga River have experienced high runoffwith respect to the stations on the Ganga River because the tributaries receive more direct runoff than the Ganga River and there is a decreasing trend in the amount of runoff from the up-stream to the down-stream of the Ganga River. In the post monsoon period Sasaram receives very lowrunoff probably because of low rainfall in the Son River basin during this time. Seasonal variability of runoff of all stations reflect that the tributaries receive more runoff than the Ganga. The construction of Farakka barrage play a significant role in the variability of runoff and discharge in downstream of the basin especially of Rajmahal, Jangipur and Nabadwip stations. The stations which are on the Ganga River receive high discharge and the stations on the tributaries get relativelylow discharge. This scenario is somehow reciprocal with the seasonal variability of average runoff of the basin.