Spatial analysis of flooded and flooded areas in Noorabad urban area using radar images and HEC-RAS model

Floods are one of the most important hazards that always cause a lot of damage to urban areas. One of the cities exposed to floods is Noorabad city in Lorestan province. Accordingly, this study has identified flooded areas as well as flood-prone areas in the urban area of Noorabad. In this study, in order to identify flooded areas and areas prone to floods, a digital model of 5 m height, 1: 50,000 topographic map, Sentinel radar images, information about Dubai and river roughness coefficient have been used as research data. ARCGIS, HEC-RAS and SNAP software are also considered as research tools. This research has been done in 4 stages, which in the first and second stages have been determined by using Sentinel 1 radar images and field visits, respectively, in the flooded areas in April 2009. In the third stage, using the HEA-RAS method, the flood-prone areas of the region have been identified and in the fourth stage, the obtained results have been compared and evaluated. The results of the evaluation of the flooded areas using radar images and field visits indicate that due to the floods in April 2019, 0.562 and 1.212 km2 of the urban area, respectively, have been flooded. The results of the HEC-RAS method also indicate that 1.542 km2 of the urban area of Noorabad is at risk of flooding with a 100-year return period. Evaluation and comparison of the results obtained through different methods indicate that the obtained results are consistent with each other. In fact, the areas identified in the field visits as flooded areas are also identified in the radar images as flooded areas. Based on the results of the HEC-RAS method, these areas are considered to be flood-prone areas.