A Group Model Building approach for climate change adaptation of agricultural systems in Northeast Lower Saxony

Climate change is expected to affect water availability for agriculture and increase the risk of crop loss. While in North East Lower Saxony (NELS) an intensification of irrigation might be a temporary solution, a long-term increase in water extraction, especially during drought periods, is not a sustainable option. Based on this issue, we implemented a participatory system dynamics approach, namely Group Model Building (GMB), to develop a qualitative system dynamics model (QSDM) describing the agricultural system and its relation to water resources in the study region. Through the development of such a model, we seek to understand the complexity of the interactions between both sectors, recognize the stakeholders’ needs and identify risks and weaknesses. By doing this, we expect to subsequently reinforce the adaptation and decision-making process and avoid conflicts. The model incorporates a wide range of perceptions, as twenty stakeholders ranging from farmers, government agencies, environmental protection organizations and local water authorities were involved in the study. Through the inclusion of a variety of perceptions, the study seeks to increase information exchange to reduce subjectivity and knowledge gaps. These perceptions were recorded and embedded in a QSDM using GMB. Through the QSDM, we identified and mapped the structure and connections between agriculture and the water balance. It was also possible to identify the strongest feedback loops governing both sectors as well as their influence on the current situation. The causal loops include the different uses for the available water of the region, the impact of irrigation, the significance of crop selection and the importance of sustainable soil management. We concluded that climate change poses a risk to the region as elevated temperatures could increase the crop water demand and increase the need for irrigation. In the same way, changes in the rain patterns could affect the water balance of the region. The agricultural system has, however, potential to adapt by implementing new water management strategies such as restructuring water rights, water storage and reuse and conjunctive water use and by changing agricultural practices.