Analysis of the impact of roughness coefficient changes due to land use changes on the hydraulics of the Kashafrood River

Abstract Mashhad's Kashafrood basin has been affected by land use changes, urbanization, and the development of agricultural water resources. This basin is located in the Razavi Khorasan province, Mashhad city. This research analyzes the impact of land use changes on river flow from a hydraulic point of view. For this purpose, the studied area was divided into five sub-basins and flood values were calculated using Deacon's method and different return periods for the sub-basins. In order to determine the intensity and extent of lateral erosion, two factors, the height of the terraces (H) and the amount of erosion activity (T), were measured, separated into different classes and evaluated. Also, the river was simulated under different hydraulic regimes. The results showed that the effects of erosion in more than 50% of the observation path and the 25-year discharge entered the bed area. The highest sensitivity to changes in the roughness coefficient is related to the flow surface and the width of the upper surface. Based on this, this research provides valuable information for land use management, understanding the impact of land use changes on river basins, and for decision-making by the executives.