Estimating the costs and benefits of landscape-based water retention measures as nature-based solutions to mitigating climate impacts in eastern Germany, the Czech Republic, and Slovakia

In eastern Germany, the Czech Republic, and Slovakia, historic policies have led to large, monocropped agricultural landscapes resulting in degradation of traditional landscapes with impacts on the local water and climate cycles. In the last 20 years, the expansion of urban and industrial areas has added to this landscape degradation. The growing interest in nature-based solutions, including landscape-based water-retention measures, is a response to reversing landscape degradation, rejuvenating ecosystem services, and mitigating the impacts of large-scale commercial agriculture and climate change. In this study, the costs and benefits of water-retention measures in east Germany, the Czech Republic, and Slovakia are assessed. Results indicate that water-retention measures, should they be implemented throughout the study area, offer potentially increased water availability over all land use classes assessed, help to increase local crop productivity, and aid in local landscape cooling. Croplands are suggested as being the best value for money, offering the greatest volume potentials (mean = 88 million m³), cooling effects (mean = -1.6°C), and productivity gains (mean = €66 million yr^-1), while also being the cheapest to implement per unit area. Differing policies in the three states will likely result in non-uniform selection or implementation of measures. Future research should focus on local-level studies offering greater practical messages beyond the regional-level analysis conducted in this work, as well as ways towards harmonising policy across the states. This work contributes to the growing body of literature assessing the costs and benefits of water-retention measures, including the potential for landscape cooling, lowering temperature gradients, and ecosystem restoration. As the world urbanises, and as more land is converted to homogeneous cropland, such measures may prove critical in mitigating climate change, landscape drying, flood runoff, and soil and nutrient loss.