Different Approach for Using Trap Efficiency for Estimation of Reservoir Sedimentation. An Overview

Abstract

Trap efficiency method of estimating reservoir sedimentation found by Brune (1953) has been widely used all over the world. This method developed the curve with the relation between trap efficiency and reservoir capacity-inflow (C/I) ratio. Many researchers used this method and developed Brune‘s methods to predict the amount of sediment trapped in reservoirs, because these methods are more versatile, accurate and quantifiable with a simple knowledge. Even though these are more accurate methods, they have constraints to use these method especially in most developing countries which do not have inflow measuring stations at upstream of reservoirs because of high cost for installing inflow measuring gauges at upstream part of every reservoir. Assuming inflow equalled to outflow for calculating capacity-inflow (C/I) ratio without taking regression analysis of their relation gave high values of C/I ratio because of evaporation and seepage losses which makes the difference. Sampling sediment inflow to the reservoir every time is also costly and time consuming for estimating sediments trapped in reservoirs by using trap efficiency verses reservoir capacity–inflow (C/I) ratio curve. Therefore, modifying these methods with easily available and reliable data makes estimation of sediments in reservoir easier and more accurate. The main objective of this review is to identify the mechanism how to modify Brune and developed Brune‘s curve for estimating reservoir sedimentation using trap efficiency verses reservoir capacity–outflow (C/Q) ratio curve. To do this 44 reservoirs which have inflow gauging stations at upstream of the reservoir and outflow gauging stations at downstream of reservoir have been selected and related the inflow (I) with outflow (Q). Finally, the relationship between inflow and outflow by regression analysis method has been developed, and then Q substituted in terms of I after regression analysis was derived.