Investigation of urban flooding in Ahvaz using the combination of spatial and hydrological analysis in GIS and HEC-RAS plugin

The study of statistics and information on annual damages caused by floods in Iran indicates the extent of flood damage to natural resources. The use of geospatial information and remote sensing technologies can be very helpful in reducing these damages and better planning. In the present study, these technologies have been used for flood zoning in the Karun River in Ahvaz city. The zoning of the study area was done by combining hydraulic model and ArcGIS software through HEC-Geo RAS extension along 33 km of this river. In order to extract the border of the river banks in the urban area of Ahvaz, the supervised classification and Landsat satellite images were used. After introducing the geometric information to the model, the value of the Manning roughness coefficient is determined for different periods and then the return periods of 2, 50, and 100 years are introduced. The maximum speeds in the return periods were 2.6, 6.15, and 7.2 m/s, respectively, which are within the allowable flood speeds. This means that if the river banks are organized and fenced, scouring, erosion, and sedimentation will not occur and water will flow in the main canal without destruction. Preparation of flood warning systems based on precipitation with a high return period that leads to extreme floods, walling, beach construction, and river management in unstable and erodible sections of the river and improving the slope of the bed and canal dredging in the required sections, including the proposed executive solutions for organizing Karun River.