Integrating Remote and In Situ Data to Compare a Watershed’s Hydrological Response under Pre- and Post-Fire Conditions

Abstract

Climate change has increased forest fire risk across Europe, leading to negative impact on air and water quality, biodiversity, soil and landscape aesthetics. Fire events in Mediterranean areas are linked to adverse effects on watersheds’ hydrological regimes and increased surface runoff. The objective of this work is to investigate the hydrological response under pre- and post-fire conditions at a catchment scale. The study area is the mountainous area affected by the recent fire events of July 2021 in Cyprus. The methodological approach that was developed and applied involves the GIS-based implementation of the time-area (TA) diagram method for the unit hydrograph (UH) determination, under the two scenarios (pre- and post-fire), as well as the estimation of hydrological losses using the SCS-CN method for both scenarios. Two typical rainfall-runoff events for return periods of 20 and 100 years are compared for both scenarios regarding total runoff volume, peak discharge and time to peak. This first investigation of hydrological changes before and after a fire event in the area leads to the conclusion that, mainly due to the reduction of vegetation and soil permeability, there is a significant increase in the peak flow discharge and the total runoff volume.

Keywords

• hydrological response
• forest fire impact
• floods
• unit hydrograph
• Cyprus