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Hydrological modeling predicts flood discharge and diminishes the danger by minimizing the environmental damages downstream. This study aimed to investigate the application of the ATHYS Models platform for simulating the rainfall-runoff relationship in Oued Laou Watershed (940 km2). The study area is characterized by strong storms associated with the highest rainfall in Morocco, as well as renowned for its regular water supply and historical flooding; for these reasons, it is classified as a vulnerable area during a rainfall event. The models of the ATHYS platform have been implemented in continuous time during (2004-2012), and in four hourly rainfall extremes recorded in March 2018 at the Kodiat Khorireen station. The VICAIR model was used to visualize, analyze and spatially adjust the input data in raster format (land use, soil numerical map, slope, and flow direction). The VISHYR model, on the other hand, was used for corrections, calculations, management, and visualization of local hydro-climatic data in the FTS63 format. Under the MERCEDES model, the combination of the Soil Conservation Service (SCS) production function and the Lag and Route (L&R) transfer function has produced satisfactory results for continuous simulation periods and for the extreme scenarios. The modeling of the flow process in the Oued Laou by the ATHYS platform produced a reasonable performance with an average NSE of 0.70, R2 of 0.73, PBIAS of 13% and RMSE of 0.46. The research results reveal that the storage parameters, soil type, land use, and vegetation are the most important factors affecting the sensitivity of the hydrological response in the Oued Laou watershed. Moreover, the results indicate that the MERCEDES model is an appropriate tool for modeling floods and flow volumes associated with specific rain events and could be used by managers and decision-makers as a tool for flood forecasting in Morocco. [ABSTRACT FROM AUTHOR]

This study evaluated the Soil and Water Assessment Tool (SWAT) model performance for modeling the portioning of rainfall in the Laou watershed (area: 940 km2) that extended over two different climatic settings in Morocco, (the Mediterranean sub-humid and the semi-arid). This research also investigated the significant parameters that affect the stream flow simulation. SWAT model was constructed during the period from 2004 to 2011. The modeled stream flow data was manually calibrated using flow gauges daily from 2004 to 2008 and validated for the volumetric flows from 2009 to 2011. SWAT model results indicate that 60% of the stream is provided by the base flow. The sensitivity analysis showed that out of 28 parameters, only 6 revealed meaningful effects on the flow simulation (CN2, ESCO, SOL_AWC, ALPHA_BF, CH_N2, CH_k2) and have the most significant influence. The model proved to be very sensitive to the base flow. Furthermore our outcome indicates that SWAT can successfully replicate the daily stream flows in Laou watershed with Nash-Sutcliffe (NSE) coefficients in the range of 0.76-0.84, R2 of 0.74-0.82, RSR of 0.52-0.41 and PBIS of 12.24-8.93 respectively. In addition SWAT was found to be suitable for both climatic regions in Laou watershed. These results reinforced the multi-functionality and reliability of SWAT as a hydrological model and a relevant tool for water resources management and controls. [ABSTRACT FROM AUTHOR]