CS(AR)-2/2006 : Dam break flood simulation and reservoir sedimentation in Maithon reservoir (Part II — Dam Break Flow Simulation)

Abstract

Dam break flow simulation study for various combination of failure of Maithon and Panchet dam on Barakar and Damodar river in Jharkhand state has been carried out using NWS DAMBRK model. The model simulates the development of breach in the dam section and routs the resulting flow in the downstream river valley using one dimensional Saint-Venant equation. The reservoir inflow for dam break analysis has been considered, instead of those mentioned in the completion report of two projects, based on a recent paper in which the PMF for Panchet and Maithon have been computed. The simulation has been performed for different scenarios of failure of Maithon and Panchet dams. Further, the analysis has also been performed for dam break failure under earthquake or terrorist attack by simulating a instantaneous failure of dams under nominal inflow in the reservoir. The failure of Maithon dam on Barakar river has been considered separately and its outflow at the confluence of two rivers has been considered as lateral inflow while simulating the dam break failure in Panchet dam over river Damodar. The maximum discharge, maximum stage and maximum flow velocity and its time of occurrence at various cross sections along the Damodar and Barakar river have been computed. The inundation maps showing the extent, depth and area of inundation have also been prepared in GIS environment. The sensitivity analyses of assumed breach parameters namely breach width, time of breach and slope of breach section have been performed for two dams separately.