Climate change induced impacts on hydrological extremes at the catchment scale: case of Wadi Siliana (North western Tunisia)

High and low flows are hydrological flow extremes threatening human being by causing floods and droughts. They are caused by meteorological extremes and human activities.  Changes in meteorological conditions will inevitably impact the frequency of hydrological extremes and exacerbate their associated hydrological impacts.

This study focuses on modelling projected change in both frequency and magnitude of flow extremes as consequence to change in climate condition in the Siliana catchment in Tunisia. The SWAT and HBV hydrological models were calibrated using historical data and fed with an ensemble of high resolution CORDEX climate models. Results project a warmer and drier hydrometeorological conditions in the Siliana catchment. The precipitation is expected to decrease in the future by an average of 10% in dry season and 12% in wet season. In contrast, temperature is expected to increase by an average of +2°C in dry season and 1.8°C in wet period.

The two models show that while magnitude and frequency of high flows are expected to decrease, low flows frequency is expected to increase which affirms that the Siliana catchment is likely to experience severe hydrological conditions with reduction in water availability and increase in drought frequency.