Calibration of the rating curve method to estimate Ghezelozan basin sediment by using observed data of Sefid-rood dam

Sedimentation in reservoirs reduces dams storage and makes many problems in their operation. Therefore accurate computation of sediment volume is essential for appropriate design and optimum reservoir management during its operation. In this research long term field data of Sefid-rood dam were used to check the sediment volume computed for Ghezelozan basin. The Computed volume of sediment by rating curve and modified FAO method was compared with real volume as the result of hydrographic surveying to evaluate and calibrate computed methods. The results showed that the rating curve method was underestimated (approximately half of real volume)، while modified FAO method estimated sediment volume 10 times more than real volume. The investigations show that the modified coefficient equal to 2 presents logical results. Therefore، it is recommended to use the modified coefficient for field usage in Ghezelozan basin. In other words، the computed sediment volume by rating curve method should be doubled to obtain real volume.