90-Dam Break Analysis of Maithon and Panchet Dams and Inundation Mapping.

Abstract

The failure of a dam is of serious concern due to involvement of loss of lives and properties. Dam break floods analysis is, therefore, important for flood disaster management. The commonly used computer programs for such analysis are NWS DAMBRK, MIKE and HEC series of models. These programs are capable of simulating the dam break flood wave and routing through river channels and downstream structures like bridges, embankments, etc. These programs can provide information about the flood inundation and warning time resulting from dam failures. The present paper analyses dam break fl ood simulation of Maithon and Panchet reservoir located in Damodar valley. The water resources of the Damodar valley have been trapped by construction of series of reservoirs on Damodar river and its tributaries. Panchet reservoir with gross storage capacity of 1358 MCM is located on Damodar river while Maithon reservoir with gross storage capacity of 1093 MCM is located on Barakar river, a tributary of Damodar. The two rivers join together at 6.4 km d/s of Panchet dam and 12.9 km d/s of Maithon dam. 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 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. Four cases of failure scenarios has been analyzed: (i) failure of only Panchet dam, (ii) failure of only Maithon dam, (iii) failure of both Panchet and Maithon dams and (iv) none of the dams fail under probable maximum flood. The maximum discharge, maximum stage and maximum flow velocity and its time of occurrence at various cross sections along the Damodar and Barakar rivers have been computed. The inundation maps showing the extent, depth and area of inundation have been prepared in GIS environment for all four cases.