Hydrologic model combined with a GIS for estimating hydrologic balance at watershed scale: application to the Macta watershed (north-western Algeria)

Hydrologic modelling techniques may help to improve the representation and functioning of interactions between different factors that exist in watersheds. Geographic information systems (GIS) provide such models with data that need to be structured in adequate form (layers and databases). This paper presents an investigation of the hydrologic balance relating to the large Macta watershed located in the north-west region of Algeria using the SWAT hydrologic model and ArcView GIS software. The Macta watershed was selected to have the capacity for significant adaptation of the SWAT model and to test the possibilities offered by this model, which takes into account the main factors that determine the hydrologic balance. Its implementation requires a database to be built for its calibration and validation. The SWAT model is calibrated for the case study and some results are presented in this paper. It seems herein that the model reproduces the parameters of climate, water balance and stream flow. The obtained results show a good correlation between simulated and observed variables for the adopted model. The model offers interesting scenarios for comprehension and simulation of phenomena at a watershed scale, which are a decision-making aid for water resources management.