Soil and water salinization in mediterranean costal area : toward an integrated approach for salinity management - Case study of the Aude lowland

Soil and water salinization is a major threat to agricultural land and biodiversity in natural areas. Coastal areas are highly sensitive to salinization leading to a deterioration of resources (water, soil and biodiversity) and ecosystem services. The Aude lowland is longstanding facing this issue. The main solution is to bring massive amounts of fresh water to the surface of the fields, in the form of anthropic flooding, associated with drainage for the leaching of salts. Understanding system equilibrium is crucial in the context of global change, less fresh water available, sea level rise, strong and fast landuse evolution.

To achieve this objective, we propose an integrated approach providing links between high resolution water and soil salinity at lowland scale, lato sensu water management practices and winegrowers perception of the actual state and evolution salinity.

Salinity measurement survey consist in three dimensional sampling with more than 1500 samples on the whole study area. Results exhibit high level of salinity, increasing with depth and heterogeneity at short distance and spatially structured at long distance. Closed questions carried out on 27 winegrowers bring an in-depth knowledge on all winegrowing practices related to water management (tillage, weed control practices, irrigation, drainage). Statistical analysis (MCA, HAC) show five groups of practices associated to different salt control strategies. Perception was investigated using open questions and answers were structured in a matrix including six themes (in column) and 27 winegrowers (in row). Main results show three different types for salinity perception.

The cross analysis between perception, practices and measured salinity brings an integrated vision of the salinization and its management in the study area. This allows to better understand how viticulture can still partially persist despite high soil and water salinity levels. The reason is inside the strategies promoting the adaptation of the practices to salty pressure and soil functioning and not only based on unique practice.