Browsing by Author "Ehsan, Saqib"

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Open Access
Evaluation of life safety risks related to severe flooding
(2009) Ehsan, Saqib; Wieprecht, Silke (Prof. Dr.-Ing.)
The flooding risk has always been considered to be very important for the risk safety management of dams. The extreme flooding downstream of a dam could be either due to dam failure or sometimes it can occur without failure. In both cases, it poses serious risks to people and property downstream of the dam. In this study, the risk assessment for the Jhelum river valley downstream of Mangla dam has been carried out. Mangla dam is one of the large earth and rock-fill dams in the world. The height of the main dam is about 125 m above riverbed after the raising of about 9.15 m (30 ft) which was planned to be completed in 2008. For this research, Mangla dam has been considered with raised conditions. The main aim of this research is to develop an improved method for loss of life estimation due to extreme flooding (with and without dam failure) downstream of a dam and to analyze the pattern of impacts depending on the downstream valley shape on possible life loss. The project reach is about 329 km long downstream of Mangla dam including different hydraulic structures. It has been modeled for unsteady flow conditions by using MIKE 11 (1D). Different catastrophic flooding scenarios with and without dam failure have been taken into consideration. Based on flood routing results, the flood severity indication has been done downstream of the dam for different flooding scenarios. In order to have more meaningful and realistic results, a new criterion for flood severity has been developed. For more precise and realistic estimates of possible life loss due to extreme flooding downstream of the dam, an improved and elaborate loss of life (LOL) estimation method has also been developed and loss of life (LOL) has been estimated for different flooding scenarios. In order to generalize the LOL results of Jhelum river valley for other river valleys in the world, new valley shapes have been produced according to the suggested changes and hydraulic modeling under unsteady flow conditions for different flooding scenarios has been carried out. This study provides new useful guidelines for the better risk assessment of existing and planned dams in Pakistan and in other parts of the world.