Flash Flood Modeling and Mitigation in Arid and Semiarid Basins: Case Studies from Oman and Brazil

Abstract

The behaviors and impacts of flash floods (FF) are different based on the climatic regions. To understand such difference, two case studies were selected for the analysis: Wadi Uday, Oman and Sume Basin, Paraiba, Brazil. The rainfall-runoff inundation model (RRI) was used to simulate the discharge and flood inundation of the recent flood events to understand the severity and frequency of flash floods to better assess the current mitigation measures. The current FF situations in arid and semiarid basins were analyzed, and the hazards associated with flood phenomenon were assessed for various calculated rainfall return periods using RRI model. To this end, a flash flood index (average water depth per total basin area) was calculated as a basis to understand the impact of flash floods. A coupling of this index with the FF histories was included to provide a comprehensive overview of the FF vulnerability of arid and semiarid basins. We concluded that FFs tend to be more severe and extreme in arid regions than in semiarid regions, despite the lower frequency of FFs and the water scarcity in arid regions. Distributed dams also proved to be more effective in preventing FFs in arid regions than in semiarid regions.

A global topography- and hydrography-based floodability index for the downscaling, analysis, and data-fusion of surface water

“…Oman and North Brazil (Saber et al, 2022)) with very complex flood responses that depend on many factors such as intense storms, steep slopes, and the lack of vegetation (Lin, 1999). The floodability index here does not account for all factors but only topography conditions, but can help to isolate pixels that are more prone to flash floods in such areas.…”