Determination of sediment volumes in dams with hydrographic surveys

Due to the drought felt both in the world and in our country caused by global climate change, effective management of our existing water resources and become imperative to make a sustainable resource by truthfully. Therefore, we need to be more careful about many issues related to our existing water resources. Sediment which is carried by uncontrolled floods or streams, affects the efficient operation of dams negatively As a result of sediment accumulation, there are losses in the storage capacity of the dams. Due to these losses, the economic life of the dams is shortened and many problems can be occurred related to operation of the dams. Storing more water in our dams, taking measures to extend the operational life and planning the stored water according to the usage areas is aimed by reducing these negative situations. In accordance with these purposes, in order to determine the amount of water available correctly, it is necessary to calculate the amount of sediment by making hydrographic measurements in our dams at regular intervals. In this study, dam sedimentation which is one of the application areas of hydrographic measurements has been investigated. In this direction, hydrographic maps of the Sarımsaklı Dam in the Kızılırmak Basin for 1972, 1982 and 2013 were used. Surface area and volume calculations at different water levels of the Sarimsakli Dam reservoir were made with the help of NetCad, Global Mapper and PDS2000 softwares by using digital terrain models of hydrographic maps of three different years. The surface area and volume values of the dam reservoir of 1972, 1982 and 2013 were observed by the calculations made with the help of three different softwares and the values obtained were compared and controlled with each other. As a result of the calculations, it was seen that the area and volume values calculated by using different softwares are compatible with each other at rate of 97%. Averages of sediment amounts and percentage occupancy rates were calculated by using the hydrographic map of Sarımsaklı Dam in 2013 and the project information in 1968 when the dam was commissioned and the average sediment amount accumulated in the dam during the last 45 years was 4,320 hm3 and the average percentage occupancy rate was 12.40%. In addition, the average occupancy in dead volume over the past 45 years was calculated as 0.429 hm3 and observed that the dead volume capacity decreased by an average of 16.43%. As a result, it is seen that there is an average volume loss of 12.40% in total volume capacity and a decrease in dead volume capacity of 16.43% in the last 45 years. In addition to the calculations, the loss observed in dam storage capacity is aimed to investigate by creating sediment distribution maps, profiles and cross-sections in more detail.