The effect of land use on hydrological processes in the Svratka river basin

The Svratka river basin represents an important water resource in the South Moravian Region of the Czech Republic. Due to its relatively low aridity index (the ratio of precipitation to potential evapotranspiration), it belongs to river basins sensitive to climate change. This is also supported by significant negative runoff trends over the past 40 years. The aim of this study is to evaluate the impacts of a hypothetical land use change on the hydrological processes of the Svratka river basin. We used a physically based and spatially distributed hydrological model Mike SHE. The Mike SHE model was calibrated and validated using measured river discharge data in the three hydrological profiles in the Svratka basin for the period 1981–2020. Several land use scenarios were tested against the reference scenario (i.e. current land use) to analyze the impacts of land use change. The land use scenarios encompassed the following hypothetical extreme changes where the entire basin in the model was changed to (i) grassland, (ii) mixed deciduous-coniferous forest, (iii) deciduous forest, or (iv) cropland. These extreme land use scenarios were tested for the baseline period 1981–2020 and also for several CMIP6 downscaled climate models and different socioeconomic pathways (emissions scenarios) up to the end of the 21^st century. The results showed that the evapotranspiration was the highest for mixed deciduous-coniferous forest while the lowest was the grassland scenario and cropland . The lowest total runoff from the river basin was simulated for both forest scenarios (mixed forest and deciduous forest). The results also demonstrated that the dominant loss component for all scenarios of the water balance in the Svratka river basin is evapotranspiration. The sensitivity of the hydrological balance in the Czech landscape was also demonstrated, where a slight increase in the evapotranspiration value in the basin has a significant effect on the total runoff from the Svratka basin. The climate change scenarios additionally suggest further exacerbating the water balance and runoff decline in the region. The results of this study are a first step towards evaluating and designing nature-based adaptation measures to climate change in the Svratka river basin.

 

Acknowledgment:
The research infrastructure and CzechGlobe team was financially supported by the SustES - Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797). The study was also supported by the Internal Grant Agency of the AgriSciences faculty at Mendel University in Brno (AF-IGA2023-IP-031).