An Investigation of the Environmental Influences on the Hydraulic Behavior of the Shour River (Case study: Kabudarahang, Hamadan county, west Iran)

The under-study drainage basin is located in Hamadan province and a part of Qezel Ozan domain. Kabudarahang under-study drainage basin belonging to which, is located in the north of the province. Along its path, the Shour River receives a number of important tributaries like Salim Saraei, Ghader Abad, Safariz, and Chahar Sough. The investigation of the hydraulic behavior of the flow and specifying the prominent characteristics of the flow like elevation, velocity, and water levels according to different discharges are all obtained through the hydraulic studies of the flow. Providing longitudinal and transverse side-views of the water level, surveying the flow regime, and specifying the effects of structures and buildings constructed on the flow are among the other consequences of the hydraulic studies. These studies have been carried out according to the hydraulic models provided using the program HEC-HMS. In order to provide the hydraulic model of the Shour river, the required information and data including the flood discharge with different return periods, the manning coefficient, the geometry and the sections of the river, and the boundary conditions have been specified for an integrated 60-kilometer interval as the input data for the modeling. Riverʹs geometrical information have been derived from 1/25000 topographic maps. Transferring the topographic maps into the GIS environment and inserting required preparative modifications and processing, the transverse sections of the river were provided and, afterwards, they were transmitted into HEC-HMS model in order to simulate the hydraulic of the flow. All the structures placed on the path of the river have also been taken into account in the study of the hydraulic behavior of the flow and their effects have undergone investigation and analysis. Results show that some inappropriate constructions like culverts or bridges may cause changes in the hydraulic condition of the river in the location of the construction. Such changes mostly bear negative consequences including supercritical flows and subsequently bed and side erosions.