Sensitivity analysis of SWAT model to the spatial rainfall distribution and watershed subdivision in streamflow simulations in the Mediterranean context: A case study in the Joumine watershed. Tunisia

The spatial variability of rainfall is often regarded as significant source of uncertainty in hydrological modelling like the Soil and Water Assessment Tool (SWAT). The objective of this work was to study the sensitivity analysis of SWAT model for a spatial distribution of rain gauges network as well as the subdivision of watershed. The lapse rate of precipitation was calculated from the relation between mean annual precipitation and elevation. It is for 70 mm/100 m. The Soil and Water Assessment Tool (SWAT) model was applied using 5 precipitation gauges and 5 watersheds delineations features. Seven methodologies precipitation options input in the model were implemented for studying the sensitivity analysis of SWAT. Simulated and measured streamflow at the watershed outlet were evaluated. Results were not calibrated. SWAT is extremely sensitive to spatial distribution of rain gauges but it is slightly affected by watershed delineations.