An interactive tool to promote rational management of Mediterranean marshes
Mediterranean wetlands are dominated by temporary and semi-permanent marshes that naturally dry out during the summer period. This unique character is due to high temperatures, which increases the processes of evaporation and evapotranspiration by plants, and are not compensated by rainfall. These conditions are ideal for certain species of flora and fauna that are adapted to drought periods, contributing to a unique biodiversity. However, water inputs are frequent in Mediterranean marshes that are exploited for various uses (reed harvesting, waterfowl hunting, cattle grazing, fishing, ecotourism). These human interventions, essentially carried out by pumping or gravity supply from rivers, reservoirs, irrigation or drainage canals, are often reliant on the increasing reclamation and modification of land use which contributes to the disconnection of wetlands from their catchment area. Rational water inputs are thus, in many cases, a necessary action to promote wetland uses, sustainable management and preservation.
Climate scenarios for the Mediterranean area predict an increase in temperatures and lower levels of summer rainfall, with a concentration of rainfall in autumn, characterized by more intense but less frequent rainy periods. In coastal areas, these changes are likely to induce a decrease in water quantity and quality (salinization and an increased use of drainage waters), at least during some periods of the year. How can we reduce water inputs and maintain socio-economic activities? How can we modulate water inputs in winter to avoid using water of lower quality at other periods? Will temporary marshes survive the predicted climate evolution without intervention on their hydrology? What are the current water volumes required for specific uses or management schemes?
What is Mar-O-Sel?
Mar-O-Sel is a simulation tool available online and developed by Tour du Valat to visualise management impacts (water inputs or outputs) on the evolution of water and salinity levels under different climatic conditions in the Mediterranean. Over a monthly time lapse, Mar-O-Sel calculates water volumes needed to achieve a desired water level. These water inputs and outputs, combined with precipitation and evapotranspiration data (obtained from historical records and predictions according to IPCC), have impacts on surface and ground water salinity, as well as on water levels over the following months. Management choices can be simulated in an interactive way to evaluate the impacts over periods of up to ten years. Water level and salinity fluctuations being amongst the principal factors influencing Mediterranean marsh flora and fauna, Mar-O-Sel also allows visualisation, when relevant to the selected area, of the impact of this management on submerged and emergent vegetation and the impact on a few groups of marsh-nesting birds.
Who can use Mar-O-Sel?
Mar-O-Sel has been developed in order to contribute to management which is sustainable and conserves the heritage of Mediterranean marshes. The tool is free to use and is intended for anybody wishing to test the impact of different management modes on marsh hydrology and biodiversity, particularly with a view to climate change. There are two types of users: identified and non-identified. To be identified, the user has to create an account with a password, no additional information is necessary. The advantages of this type of use permits the saving of different management scenarios and to export simulation results to an excel file.
"All models are false, but some are useful"
Like all modelling tools, Mar-O-Sel is the simplified version of a complex reality. The water level and salinity values resulting from simulations should be considered as relative rather than absolute. Additionally, water and salinity are not the only factors influencing marsh flora and fauna. Nevertheless, the combination of hydrology data and vegetation structure or composition explain a large part of observed variations concerning the presence or abundance of several reed-bed bird species, justifying the interest of integrating them to Mar-O-Sel.