Assessment of the Potential Flood Hazard of the Larbaâ Wadi, Rural Center of Sebt Boukellal, Taza, Morocco

Abstract

Flood risk management often requires the use of geomorphological features to identify flood zones, and the use of hydraulic models to predict inundation dynamics and related impacts on the surrounding area. In this study, we used a hydraulic river simulation model to identify potential flood-prone zones on a small scale. It concentrated on a 2.5-kilometer section of the Larbaâ Wadi, which crosses the rural center of Sebt Boukellal. For estimating the peak discharge that occurs in the return periods of 10, 20, 50, and 100 years of the drainage area, we used the Rational method. Standard tables to estimate Manning’s coefficient and direct field measurements to feed the model. Model simulation has shown stability of the steady state, which witnesses the accuracy of the estimated and measured characteristics of the river system. During the calibration phase, we compared the model outputs to the observed floods and made adjustments to align the simulation with the field observations. Indeed, the 50-year flood remarkably matched the extent of the flood that occurred on September 27, 2000. The obtained results have shown that even for a 10year return period, the overflow affects properties within the floodplain. The 100-year flood exceeded the river’s capacity, causing water to spill onto the rural center’s streets and cultivated fields. The water level reached an elevation of 552.14 meters at Sebt Boukellal’s marketplace. These results were consistent with recent floods and confirm previous observations, indicating that the model precisely predicted the river’s behavior. The findings have shown that floods spanned large regions and suggested urgent intervention to protect lives and properties.