Document Type : Original Article
Authors
1
Ph.D. Student of Depatment Water&, Hydrology Faculty of water and Environmental Chamran University Ahvaz, Ahvaz, Iran.
2
Associate Professor, Department of Hydrology and Water Resources, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
3
Professor, Department of Hydrology and Water Resources, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Abstract
Introduction
Gilan-e Gharb Reservoir Dam in Gilan-e Gharb County in the southwest of Kermanshah Province is one of the dams designed to provide agricultural water to downstream lands in a hot and dry region. This dam is one of the structures where the calculation errors in the estimation of the water entering the reservoir have caused the failure of the planned goals in such a way that to compensate for this calculation error and to supply agricultural water to the Gilan-e Gharb dyke area in front of the Gilan-e Gharb spring flow, it was designed and was executed After 25 years of dewatering this dam, the volume of the reservoir has not yet reached the estimated value. The studying consulting engineers company mentioned the reason for this failure due to the quality of the reservoir dam inlet station, the quality of statistics and information, the occurrence of drought, and finally the effects of watershed operations in the catchment area of this dam. The main purpose of this research is to evaluate the methods of estimating the inflow to the Gilan-e Gharb dam reservoir and to investigate the factors affecting the calculation errors by using HEC-HMS software to analyze the runoff rainfall model of the Gilan-e Gharb dam reservoir and to investigate the effect of water management operations on the productive runoff and peak flood discharge.
Methodology
In this study, maps of land use, geology, vegetation and soil hydrological groups were prepared along with field assessments, and then the CN map of the basin was prepared from the integration of the said maps using GIS software. According to the historical record of the statistics and information of the inlet station of the Gilan-e Gharb Reservoir Dam in recent periods and even before the construction of the Reservoir Dam, the volume of the reservoir due to several reasons such as the low amount of incoming runoff, the existence of karst formations that collect most of the runoff, the volume of runoff with the amount 17 million cubic meters does not match.
Results and discussion
The results of this research showed that the estimation of the dam inlet was accompanied by gross errors due to the lack of knowledge of the hydrological conditions of the reservoir dam area. Taking into consideration that the watershed operations in the carried-out periods have also had an impact on the water intake of the mentioned reservoir dam, the watershed cannot be the main obstacle for not reaching the predicted watershed.
Conclusions
The results of this study showed that the methods of estimating the water input to the Gilangreb dam reservoir due to the use of statistical relationships and its extension could not be in accordance with the basin realities and the construction of this dam with high costs actually did not reach the pre-designed goals.
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