Climate- and socio-economic resilient water governance - a model framework based on WEFE indicators

As a result of climate change, heatwaves, droughts and extreme precipitation events are becoming more frequent. These lead to drought damage in forests and crop failures, but also to erosion and flooding. In addition to climate change, changes to the landscape caused by humans (drainage, soil compaction and sealing) are also affecting the natural landscape water balance. This has a negative impact on people and ecosystems and can lead to competing demands and conflicts between different sectors.

A climate-resilient landscape water balance is essential for sustainable water resource management. The WEFE (Water-Energy-Food-Ecosystem) nexus offers an integrated and coordinated approach across all sectors to reduce trade-offs and increase the efficiency of the entire system through synergies.

The overall objective of the study is to provide decision-makers with a planning framework to assess the impact of different adaptation measures on the WEFE sectors under climate change scenarios. The model framework is based on a system of indicators. The indicators themselves are derived from the results of the ecohydrological SWAT+ model and integrated into an assessment framework by the stakeholders through individual weighting.

The Upper Main catchment in Bavaria, Germany, is used as case study. The varying distribution of precipitation and the low storage capacity of the soils in some areas of the Upper Main region lead to scarce groundwater supplies. In particular, the consecutive dry years (2018, 2019, 2020 and 2022) had a negative impact on the water balance and led to falling groundwater levels, low water levels in streams and crop failures in agriculture. In contrast, the heavy rainfall in June 2024 led to flooding in some regions.

In order to investigate the landscape water balance of the Upper Main area, first a SWAT+ model is setup, calibrated and validated. The model results are then applied to quantify the indicators and evaluate the efficiency of adaptation measures on different WEFE sectors under consideration of climate change.

Furthermore, trade-offs and synergies between the different indicators are identified. The results can be used by decision-makers to develop concrete plans and strategies for sustainable and resilient water management under climate change scenarios.