Drivers influencing streamflow changes in the Upper Turia basin, Spain

Area of Science:

• Hydrology
• Environmental Science
• Climate Science

Background:

• Global river systems face streamflow reduction due to multiple interacting drivers.
• Climate change (CC) and land use/land cover changes (LULCC) are key factors influencing water availability.
• Disentangling individual driver impacts on streamflow is challenging due to their simultaneous effects.

Purpose of the Study:

• To isolate and quantify the specific impact of LULCC on streamflow reduction in the Upper Turia basin (1973-2008).
• To compare the influence of LULCC against climate change drivers on hydrological alterations.

Main Methods:

• Utilized regression models incorporating climatic variables and LULCC data to analyze annual streamflow.
• Employed the Soil and Water Assessment Tool (SWAT) ecohydrological model to simulate streamflow changes under LULCC scenarios.
• Analyzed time-variant drivers affecting the Turia river basin's water balance.

Main Results:

• LULCC significantly affects the water balance but is not the principal cause of streamflow reduction in the Upper Turia.
• Increasing mean temperatures were identified as the main driver of increased evapotranspiration and subsequent streamflow decline.
• LULCC and CC exhibited an offsetting effect: rising temperatures reduced streamflow, while LULCC (shrubland clearing, forest degradation) reduced evapotranspiration, partially counteracting this effect.

Conclusions:

• While LULCC plays a role, rising temperatures are the dominant factor in Upper Turia's streamflow reduction.
• Understanding the interplay between LULCC and CC is crucial for effective water resource management.
• The methodology provides a framework for assessing LULCC impacts on hydrological responses in other river basins.