Comparison of different targeting methods for watershed management practices implementation in Taleghan dam watershed, Iran

Abstract

Soil erosion and sediment control is important in watersheds with planned dam construction. For an efficient implementation of watershed management practices, identification of critical areas is vital. Many studies have made an effort to identify and prioritize critical sub-watersheds. But very limited studies have been conducted to rank sub-watersheds in terms of their sediment yield contribution at the watershed outlet. Therefore, the goal of this study is spatial priority of critical sources areas in Taleghan dam watershed based on three methods: (1) SSY-S: specific sediment yield at sub-watershed outlet (sediment yield/area), (2) SY-W: sub-watershed contribution to the sediment yield of the main watershed outlet/reservoir, and (3) SSY-W: specific sediment yield contribution of sub-watershed to the main watershed outlet/reservoir. The results of sub-watershed and prioritization showed that sub-watershed 22 has the highest sediment yield at its own subwatershed outlet and main outlet of watershed. Also, implementing conservation practices in a high priority area shows a decrease in sediment yield at watershed outlet. However, sediment yield at outlet of watershed decreased about 11%, 15% and 17% from baseline scenario in methods 1, 2 and 3, respectively. The results show that the SSY-W method was more effective at reducing sediments entering the reservoir of Taleghan dam.