Investigation of Hydrological and Morphological Changes in Givi chay Due to the Construction of Givi Dam

In this research, we have used images of eight and seven Landsat, topography and geology maps, hydrological and field data. First, in order to investigate the hydrological changes in the study area, the data between the two Abgarm and Firouzabad stations, using the 27 hydrologic indicators, was investigated. In the next step, the t-test was used to analyze the significance of hydrologic changes. Then, using water indicators, the river route was extracted from satellite imagery. In the next step, the river was divided into four intervals and eight routes, and river geomorphology parameters including curvature coefficient, central angle and sinusoidal coefficient of path were measured.According to the results of this study, the construction of the Givi dam and its associated implications have exacerbated the hydrological changes followed by river morphological changes. The maximum effect of dam construction was on maximum flow changes, which decreases peak flow after water absorption, and decreases the amount of sediment input downstream in the second interval by sediment trapping by Givi dam. Therefore, reducing the sediment load increases the transfer capacity by the outlet water from the dam, resulting in increased wear and tear strength and substrate digging in the second interval. In the third interval, the erosion is increasing, leading to the formation and development of the meander pattern. In the fourth interval and at a distance from the dam, the depth and width of the bed decreases due to sedimentation.