J.S.Yeoh - Department of Civil Engineering, University of Bristol, UK
J.H. Loveless - Department of Civil Engineering, University of Bristol, UK
A.M. Siyam - University of Khartoum, Sudan

The primary use of a trap efficiency function (TEF) is to predict the useful life or remaining capacity of a reservoir. Currently TEFs for reservoirs are generally empirically based and are obtained by fitting data collected from existing reservoirs. The most widely used TEF is that of Brune (1953). Many researchers have questioned the use of the capacity to inflow ratio, (V/I ) alone of the TEF of Brune (1953) to describe the dynamics of sedimentation in reservoirs (Gottschalk, 1964 and Heinemann, 1981). In this paper a newly developed generalised TEF in which the reservoir sedimentation problem is viewed as analogous to the mixer tank problem is presented. A sedimentation coefficient β is introduced to reflect the decay of storage capacity in reservoirs to relate theTEF of reservoirs to that of a mixer tank. Based on the newTEF, an analytical expression has been formulated for predicting the useful life or remaining capacity of reservoirs.