Modelling climate change impacts on crop productivity and the role of hedgerows in mitigating drought risk in Lower Austria

Agricultural drought, defined here as insufficient soil water availability to sustain crop growth during the vegetation period, is an emerging climate risk in Lower Austria. Although the region has historically benefitted from relatively reliable summer precipitation, recent decades have seen an increasing frequency of dry spells and heat periods, with direct consequences for crop yields and farm income. This study presents results from a regional agricultural drought risk assessment that evaluates crop-specific changes in drought risk under current and future climate conditions and explores the potential moderating effects of nature-based solutions in the form of hedgerows.

The assessment builds on the CLIMAAX drought risk workflow, which integrates climate variables, soil moisture dynamics, and evapotranspiration into a process-oriented crop production model. For application in Lower Austria, the workflow was adapted to incorporate regionally specific information, including irrigation infrastructure, soil characteristics, and dominant production systems. This allows drought risk to be assessed not only as a function of climate forcing, but also in the context of local agronomic and socio-economic conditions.

At the core of the model is a daily simulation of crop water demand and supply throughout the growing season. Gridded climate data (temperature, precipitation, radiation, humidity, and wind) are combined with soil parameters such as available water capacity and rooting depth to determine periods of water stress during critical phenological stages. These deficits are then used to estimate potential yield losses, enabling spatially explicit estimates of drought impacts. Simulations are performed for a historical baseline as well as mid- and end-century climate scenarios under RCP4.5 and RCP8.5. The workflow was adapted to estimate annual yield losses, accounting for extreme drought years which would otherwise be masked by period averages.

To evaluate the role of nature-based solutions in mitigating agricultural drought, the current extent of multifunctional hedgerows and a set of hedge scenarios were incorporated into the model. Microclimatic effects of hedgerows on evapotranspiration were represented using empirical change factors derived from field experiments in Lower Austria (Orfánus and Eitzinger, 2010). These factors describe a linear reduction in evapotranspiration in the lee of an 8 m high hedge, ranging from 0.5 at the hedge to 1.0 at a distance of 80 m, and were applied based on prevailing wind direction. High-resolution (10 m) simulations were made for selected drought years to capture local hedge effects on soil moisture and crop water stress.

Results indicate declining productivity for maize, sugar beet, soybean, and sunflower across all climate scenarios, while wheat and barley show increasing yield potential compared to the baseline scenario. Hedge scenario simulations demonstrate a measurable reduction in drought stress during dry years, underscoring the potential of multifunctional hedgerows as a supportive landscape-scale adaptation measure that can simultaneously mitigate drought risk and soil erosion. While hedgerows may introduce trade-offs related to shading and competition under average moisture conditions, the modelling framework provides a robust basis for identifying climatic and spatial contexts in which their net effect on crop productivity is positive, thereby supporting targeted and climate-resilient implementation strategies.