Dibang River Training Studies at Arunachal Pradesh, India

Dibang River is a tributary river of the Brahmaputra that originates and flows through the Mishmi Hills and northeast India from the state of Arunachal Pradesh. The river meets Brahmaputra upstream of Guwahati near Assam. Newly built 6.2 km long Bridge ((28° 06′ 54.1″ N 95° 49′ 10.9″ E)) is a beam bridge across Dibang River which connects Bomjir and Malek villages and provides all-weather connectivity between Dambuk and Roing in eastern part of Arunachal Pradesh, India.. Continuous migration of the river towards right bank and heavy rainfall in July 2020 resulted in heavy flow of runoff water in the Dibang river resulting a breach in guide bund which is situated 600 M upstream of bridge. Studies done include desk studies with satellite imageries, survey along river bed profile, analyses of rainfall, numerical model and design of remedial measures. Based on the numerical model studies, it was found that the river carries a discharge of 30000 m3/s without overflowing. Remedial measures were proposed as per IRC: 89—1997 which is combination of river training and embankment strengthening adopting gabions using locally available stones and seven repelling spurs at 600 m upstream of bridge. Post monitoring indicates good accretion between spur and scouring of revetments in non-spur locations. Hence, additional three more repelling spur was proposed. The details of studies and geometry of remedial measures are presented.