Flood hazard susceptibility assessment in Chiffa wadi watershed and along the first section of Algeria North–South highway using GIS and AHP method

Flood susceptibility mapping and assessment are essential to determine adequate protective measures to ensure an area or infrastructure’s safety. This study aims to assess the susceptibility to flood hazards in the Chiffa wadi watershed and, alongside an important socio-economic project, the North–South highway’s first section. The applied approach, a combination of qualitative and quantitative methods, provided valuable results despite the lack of inventory of previous floods in the watershed. First, the triggering factors were selected based on field observations and climatic analysis. Then, the factors were mapped using a set of remote sensing data and other public institution data. Finally, the analytical hierarchy process (AHP) was used to weight and combine the factors. The calculated flood hazard susceptibility index was used to map the extent of this phenomenon using GIS techniques. An innovative approach was also used by combining the resulting flood hazard map with the road chaining plan to identify the most susceptible segments to flood hazard by kilometric points. The results indicate that 49.08% of the total section is highly to very highly susceptible to flooding. The results obtained can help the authorities to develop protection strategies to ensure the safety of the infrastructures and their users. Finally, the integration of geospatial techniques and AHP based on field observations and climate analysis in flood hazard assessment is a cost-effective and rapid approach and can be used in other geohazard assessments affecting the same infrastructure.