The effect of dam construction on the hydrological indicators of Shamil and Nyan dams in Hormozgan province

It is necessary to evaluate the effects of the construction of man-made structures, including dams, on river regimes to optimally exploit water resources. Therefore, in the current study, the effects of the construction of the Shamil and Nyan dams in Hormozgan province on the hydrological indicators and environmental flow components of the Shamil River were evaluated and analyzed using IHA hydrological indicators. The results of the evaluations showed that the construction of the Shamil and Nyan dams has changed the flow regime. After the construction of Shamil and Nyan dams, the flow of the river has decreased only from the middle of November to the end of February at the same time as the harvesting of off-season crops in Hormozgan province, and the flow of the Shamil river has increased in the rest of the months. Also, floods with a return period of more than 10 years after the construction of the dam did not occur and the trend of small floods after the construction of the dam became regular so that the peak discharge of small floods in the period before the construction of the dam was 80.23 and in the period after the construction of the dam was 75.50 m3.s-1 and has decreased by about 6%. Day numbers of minimum flow have increased from 294 days before the construction of the dam to 301 days after the construction of the dam. On the other hand, the low limit flow timing index showed that the lowest flow limit changed from 46 days after the construction of the dam to 275 days in the period after the construction of the dam. The results of the present study can be used as a basis for the sustainable management of water resources of the Shamil River.