1 HYDROLOGICAL TREND ANALYSIS OF THE GANGA FLOW AT FARAKKA BARRAGE Titas Ganguly, Amit Kr. Dubey, Subashisa Dutta, Suresh A Kartha, Bimlesh Kumar Department of Civil Engineering, IIT Guwahati, Assam, P.I.N.-781039 Contact: titas@iitg.ac.in / subashisa@iitg.ac.in ABSTRACT River Ganges, one of the most valuable water resource systems in Indian subcontinent, supports the socio-economical status of India and Bangladesh. Being a large river basin of 1.25 million km 2 in India and Nepal, the river is fed by both monsoon rainfalls and Himalayan snow melting runoff. Since 1980s, many water resources development in terms of extensive agriculture, hydropower projects, water use in industries and water demand increase in the urban areas has been progressively taking place within the basin. The hydrological changes of the basin due to both anthropogenic and natural causes need to be assessed at the basin scale. In this study, two major objectives addressed are the performance of a hydrological model in predicting long-term hydrological trend and to obtain the temporal trend analysis of the Ganges flow for the monsoon period, dry season and for the annual water yield at Farakka Barrage. First, a semi-distributed hydrological model, Soil Water Assessment Tool (SWAT) was used to simulate monthly flow over a period of 1975-1995. In this model the spatial input data such as land use/land cover, soil layers and Digital Elevation Model (DEM) were used to define the spatial variability of runoff generation process within the basin. The gridded daily rainfall and temperature data was also incorporated into the *Name of conference speaker: Titas Ganguly