Modelling the hydrological balance in semi-arid zones is essential for effective water resource management, encompassing both surface water and groundwater. This study aims to model the monthly hydrological water cycle in the Wadi Mina upstream watershed (northwest Algeria) by applying the Soil and Water Assessment Tool (SWAT) hydrological model. SWAT modelling integrates spatial data such as the Digital Elevation Model (DEM), land use, soil types and various meteorological parameters including precipitation, maximum and minimum temperatures, relative humidity, solar radiation and wind speed. The SWAT model was calibrated and validated using data from January 2012 to December 2014, with a calibration period from January 2012 to August 2013 and a validation period from September 2013 to December 2014. Sensitivity and parameter calibration were conducted using the SWAT-SA program, and model performance evaluation relied on comparing the observed discharge at the outlet of the basin with model-simulated discharge, assessed through statistical coefficients including Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R²) and Percent Bias (PBAIS). Calibration results indicated favourable objective function values (NSE=0.79, R²=0.93, PBAIS= −8.53%), although a slight decrease was observed during validation (NSE=0.69, R²=0.86, and PBAIS= −11.41%). The application of the SWAT model to the Wadi Mina upstream watershed highlighted its utility in simulating the spatial distribution of different components of the hydrological balance in this basin. The SWAT model revealed that approximately 71% of the precipitation in the basin evaporates, while only 29% contributes to surface runoff or infiltration into the soil.

A comprehension of the erosion processes and sediment transport in the watershed is essential for the sustainable management of the water resources and soil fertility. In this study, the Water Assessment Tool (SWAT) model was applied to demonstrate its ability to modeling the suspended sediment transport in the Wadi K’sob basin (Northeast of Algeria). The data used to set up the SWAT model are the Digital Elevation Model (DEM), land use, soil types and weather data. The calibration was carried out using daily sediment yield data corresponding to two (2) periods( 10/10/2006 to 06/17/2007 and 10/29/2012 to 10/22/2013) and validation was performed using two (2) other periods (06/18/2007 to 11/19/2007 and 10/23/2013 to 09/13/2014) of daily sediment yield. R-SWAT code was used for calibration process and sensitivity analysis. The performance of the SWAT model was evaluated by the Nash–Sutcliffe criterion (NSE) and coefficient of determination (R²). The results obtained after calibration oscillating between good and satisfactory where (NSE = 0.67 and R² = 0.73) in the first calibration period and (NSE = 0.65 b and R² = 0.67) in the second period. For validation, the performance of the SWAT model was very good (NSE = 0.78 and R² = 0.79) in the first period while in the second period the prediction of the model was satisfactory (NSE = 0.52 and R² = 0.54). In addition, the validation process revealed that some parameters are stable and related on watershed characteristics while other unstable parameters depend on soil properties especially soil permeability and soil erodibility.