Predicting impacts of climate change on evapotranspiration and soil moisture for a site with subhumid climate

Abstract

The current and ongoing climate change over Europe can be characterized by statistically significant warming trend in all seasons. Warming has also an effect on the hydrological cycle through the precipitation intensity. Consequently, the supposed changes in the distribution and amount of precipitation with the continuously increasing temperature may induce a higher rate in water consumption of the plants, thus the adaptation of the plants to the climate change can be critical. The hydrological impact of climate change was studied based on typical environmental conditions of a specific agricultural area in Austria. For this purpose, (1) a monthly step, Thornthwaite-type water balance model was established and (2) the components of the water balance were projected for the 21st century, both (a) with a basic rooting depth condition (present state) and (b) with a (hypothetically) extended rooting depth (in order to evaluate potential adaption strategies of the plants to the warming). To achieve the main objectives, focus was set on calibrating and validating the model using local reference data. A key parameter of the applied model was the water storage capacity of the soil (SOILMAX), represented in terms of a maximum rooting depth. The latter was assessed and modified considering available data of evapotranspiration and soil physical properties. The adapted model was utilized for projections on the basis of four bias corrected Regional Climate Models. An extended rooting depth as a potential adaptation strategy for effects of climate change was also simulated by increasing SOILMAX. The basic simulation results indicated increasing evapotranspiration and soil moisture annual mean values, but decreasing minimum soil moisture for the 21st century. Seasonal examination, however, revealed that a decrease in soil moisture may occur in the growing season towards to the end of the 21st century. The simulations suggest that the vegetation of the chosen agricultural field may successfully adapt to the water scarcity by growing their roots to the possibly maximum.