A GIS-based study on channel variation, erosion and deposition along the bank of Dibru Saikhowa National Park (1967–2016), Assam, India

The GIS technology presently has become an important tool for various fluvio morphological studies. The present study incorporates GIS technology to assess more precisely and accurately the rate, nature and pattern of channel variations along with erosion and deposition of the study area at the spatio-temporal scale. The Dibru Saikhowa National Park is a river island in the upper Brahmaputra valley of Assam. The island experiences frequent bank erosion by Siang and Dibang River in the north and Lohit River in the south. The total geographical area of Dibru Saikhowa National Park was about 337.96 sq in the year 1967, which reduces to 302.45 sq km in 1988, 279.38 sq km in 2001 and finally to 241.82 sq km in the year 2016. The area witnessed a net loss of 96.14 km of area (1967–2016) with total erosion of 103.84 and deposition of 7.707 sq km of area. The southward shift of Siang and Dibang River channel/bank line and northward shift of Lohit, Dibru and Dangori channel/bank line causes erosion of Dibru Saikhowa National Park. The study reveals an average shift 1425.58 m of Dibru and Dangori channel/bank line northward and 1314.97 m of Siang and Dibang channel/bank line southward during 1976–2016. The westward shift of Dibang and Siang River conjunction along with avulsion of Lohit River southward promotes erosion of the island.