Assessing the hydrological water balance of the poorly gauged semi-arid Oued Cherraa basin in northeastern Morocco using the SWAT model

Water resources management in semi-arid areas is facing increasing difficulties, which include climatic variability, excessive use of groundwater resources, and poor hydrometeorological network coverage, over-extraction of groundwater resources, and poor hydrometeorological network coverage. The main objective of this research is to apply the SWAT Water Budget module in estimating the hydrological water balance of the poorly gauged basin of Oued Cherraa in the Moulouya watershed in northeastern Morocco. It aims at quantifying the main components of the water balance: precipitation, evapotranspiration (ET), surface runoff, and groundwater recharge, on the one hand. On the other one, it is about analyzing their spatial variability in a data-scarce context. The SWAT model was implemented using available climatic data and daily discharge data from one hydrometric station called Tazarhine. The model was calibrated and validated using the SUFI-2 algorithm within the SWAT-CUP interface. The accuracy of the model simulation was considered to be acceptable due to the efficiency values of Nash–Sutcliffe efficiency being 0.58 and 0.60 for calibration and validation, respectively, as well as the percentage bias being minimal at − 9.1% and − 0.2%, also for calibration and validation, respectively. Moreover, sensitivity analysis indicated that the most influential parameters to the simulations are RCHRG_DP, ALPHA_BF and CN2. From water balance analysis, evapotranspiration is estimated to be responsible for almost 89% of precipitation, while surface runoff is less than 6%. Recharge of shallow aquifers is much more significant compared to recharge of deep aquifers, while irrigated areas demonstrate groundwater depletion. It is evident from these results that groundwater resources available in semi-arid areas where there is no adequate monitoring system are quite fragile, which proves the importance of SWAT as a decision-support tool.