Dam break analysis using mike11 for lower nagavali dam and rukura dam

Abstract

The society gets benefited in many ways from the dams but what if dam fails? The consequences are devastating to the society; causes extensive damage to properties and loss of human life due to short warning time available. So, the safety of downstream area is one of the most important aspects during the planning and designing of dam. It is always assumed that large magnitude of flood wave is generated due to failure of dam and inundates large area along the downstream portion of river. This Thesis mainly provides an overview of the methods used to predict the breach outflow hydrographs with a detailed case study of hypothetical breach failure of two dams “Lower Nagavali Dam” and “Rukura Dam” using Mike 11 software. The two Dam breaks are analyzed for failure with comparison of the hydrographs at different downstream locations by changing its breach parameter using Mike 11. The parameters describing a breach are typically taken to be the breach depth, width, side slope and breach formation time. Wahl (1998) and Wahl (2004) and Froehlich (2008) have found them to be very significant, especially the time parameter. The results are able to provide information for preparation of Emergency Response plan. It has been concluded that for Lower Nagavali Dam the downstream area from 12 Km to 17 km is more flooded. Rukura Dam break contribute 16018 m3/s of flood into the Brahmini River. Beside the dam break analysis the sensitivity analysis for various parameters which will affect the maximum discharge and maximum water level has been analysed.