Numerical Simulation of Tarbela Reservoir Sedimentation using SSIIM-II Model

Abstract

Tarbela dam is one of the largest earth filled dams in the world used for power generation and irrigation purposes in Pakistan. Like other reservoirs all over the world, Tarbela reservoir is also exposed to sedimentation which has reduced its live storage capacity from 11.62 MAF (1977) to 7.1 MAF (2014). This sedimentation has exposed the dam to liquefaction, especially in case of any seismic activity. Pakistan will be deprived of 3478 MW hydro-power generation when Tarbela dam is redundant due to sedimentation or liquefaction. Since sedimentation is a 3D phenomenon, a 3D software named SSIIM-2 is used to simulate flow and sedimentation of Tarbela reservoir in this study. This software requires geometrical, hydrological and sedimentological data which is very well maintained by Tarbela dam authorities. Numerical model is prepared on geometrical data of year 2007 and is run for 8 years i.e. till 2014. The bed profiles attained from model are plotted against actual annual survey report of year 2008 and sensitivity of model is checked for time step, bed roughness, active layer thickness and bed shear stress.