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

Document Type : Research Paper


1 Water resources expert, YEKOM consulting engineers, 133 Muzaffar Str. (North Saba), Vali Asr Square, Tehran 14167- 93197, Iran

2 Technical director, Bureau of engineering affairs and technical standards of water and waste water, Ministry of Energy, Tehran, Iran

3 Water resources expert, Policy making on water allocation group, Ministry of Energy, Tehran, Iran


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.


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