Investigating sediment changes during dry and wet periods at both upstream and downstream stations of the Karkheh Dam

Abstract

Estimating sediment yield accurately in watershed areas is always a concern for planners. A noteworthy aspect in this regard is the variation in river behavior within watershed areas during dry and wet periods. The objective of this study is to investigate sediment variations during dry and wet periods at both upstream and downstream stations of the Karkheh Dam. To achieve this, flow and sediment statistics from the Afrineh-Kashkan station upstream of the dam and the Pay-Pol station downstream, spanning a 38-year period (1350-1398), were utilized. For this purpose, dry and wet periods were initially identified, and for each, sediment rating curve was plotted. To enhance the sediment rating curve relationship, corrective factors including FAO, QMLE and Smearing were employed. Performance evaluation of each was conducted using indicators such as RMSE, ME and P. The results of the sediment analysis at each station during dry and wet periods indicate that the specific sediment yield has decreased during dry periods and experienced a significant increase during wet periods. Moreover, the specific sediment yield at the downstream station (Pay-Pol) of the Karkheh Dam has also shown a considerable reduction, indicating the dam's impact on sediment regulation downstream.

Keywords

• dry
• wetness
• sediment rating curve
• flow discharge
• sediment load