Assessing the influence of the Al Wahda dam commissioning on flood flows and low water levels in the Gharb Plain, Morocco

Abstract

The Sebou Basin is one of the most important hydrographic basins in Morocco. When the Wadi Sebou enters the Gharb Plain, it encounters difficulties in evacuating its waters during wet years due to its flattening, resulting in risks of floods. Its flow decreases during drought years and in August and September. For the purpose of this research, we were granted authorization to utilize the hydrometric station located in Bel-Ksiri. This station is most suitable for the study as it was designated as a reference point for the Wadi Sebou's flooding in the lower basin. This study is based on detecting floods in the Wadi Sebou from 1976 to 2020, dividing this period on pre and post 1997, corresponding to periods before and after the construction of the Al Wahda dam, examining the mean daily flow rates. Identifying discontinuities within the maximum daily flow series from 1967 to 2020 was achieved in Microsoft Excel. Additionally, determining flood return periods and examining low water flows are integral aspects of the study. The findings indicate a relative decrease in the frequency and intensity of floods within the Wadi Sebou's basin, coupled with effective control of low water levels. These changes are attributed to the construction of the Al Wahda dam, which guarantees a stable water supply for irrigation purposes in the plain. To ensure the long-term sustainability of water management practices, the adoption of innovative irrigation technologies is deemed necessary.