RESERVOIRS SEDIMENTATION ANALYSIS: A CASE STUDY, DOKAN DAM; IRAQ

Abstract

Dokan dam is one of the major and strategic dams in Iraq. The importance of this water resources project comes through the functions for which it was built in 1959 i.e. irrigation, flood prevention, hydropower generation and tourism. Trials to estimate the status of the storage zones are done using the bathymetric survey; but sedimentation study was not conducted to predict the storages through the life of the dam even in the pre-implementation stage. In this study, sediment estimation analysis performed using three different approaches, Empirical Area Reduction (EAR), Area Incremental (AI), and Non-iterative Processed Empirical Distribution Model (NPEDM) for 200 years of the project life span. The average rate of the siltation estimated as 3.8 million m3 / year, and the estimated rate is closed to the rate estimated by the consultants of the project “Binnie, Deacon, and Gourley” as 4 million m3/ year in 1955. Analysis showed that EAR method is the best method to predict the actual siltation processes in Dokan dam as per the results of storage capacities and river bed rising. Other methods (AI and NPEDM) estimated the storage capacities well, but the results in prediction the status of reservoir bed an inaccurate. Capacities in different storage zones at different projected time intervals has been predicted and compared with the observed data of the dam. Here endeavor to figure out the pattern of sediment distribution considering the spatial and temporal variation of siltation processes which help to prepare the necessary steps for sediment management in future to ensure maximum benefits of the stored water. Further, sediment management has been analyzed using RESCON 2.2 Beta would to evaluate the best techniques for future enhancing dam functions. The results of this study could be utilize as a guideline for the reservoir’s owner to evaluate the operational rules