System-Dynamic models for groundwater management in SW Messinia, under different climatic scenarios

SW Messinia, Greece, is an interlinked coastal-inland area in the Eastern Mediterranean region. Extensive olive tree plantations and tourism are the main human activities in the area, both of which depend on groundwater resources to cover their irrigation and supply needs. The same groundwater sources are also the main freshwater sources for the Gialova lagoon, a coastal wetland with high ecological and commercial value. The combined effect of human interventions and climatic conditions over a period of 60 years has led to increased saline conditions in the wetland since the 1960s, and unless freshwater inputs are enhanced by restoring hydrologic connectivity between the wetland and the surrounding freshwater bodies, salinity in the lagoon is expected to increase even more under drier and warmer conditions predicted to occur in the future (Manzoni et al., 2020). However, surrounding fresh water bodies have high nutrient inputs and unless these are reduced, any increased connectivity could further degrade the sensitive ecosystem of the wetland (Bray et al., submitted). Under the COASTAL EU project, we have developed a System Dynamics model that combines tangible (e.g. runoff, water demand, salinity, population, tourist arrivals) and intangible (such as awareness and willingness to cooperate) attributes of the local social ecological system. This model is used as a basis for discussions with local stakeholders and for promoting social learning by connecting local concerns with lagoon management. These connections are considered essential for achieving the transition towards collaborative integrated agricultural practices that will enable the restoration of lagoon connectivity accounting for changing climatic conditions (increased temperature, reduced precipitation).