Modelling the interaction between shallow and deep groundwater

The following note purposes the application of a physical model (SWAP) to a system characterized by the joined presence of shallow and deep groundwater and an agricultural drainage system, aiming at the characterization of soil and water salinization process. The SWAP model has been developed by the University of Wageningen (Wageningen University Soil Physics, Ecohydrology and Groundwater Management Group) and the Alterra-team Integrated Water Resources Management and it is nowadays widely utilized for agro-hydrology applications. The model is able to simulate the main soil agro-hydrological processes in one-dimension (evapotranspiration, root water uptake, water movement, drainage and solute dynamics). The model is also able to take into account the physical processes regulating the transpiration phenomenon depending on crop and soil water characteristics (quality and quantity). Simulations will be carried out applying the model under different natural situations, represented by variations in the bottom boundary conditions, reproducing changed conditions of the deep groundwater, in terms of quality and quantity. Trials will be made also considering the influence of variations in irrigation water quantity and quality. The model output results, coming from simulations of different agricultural drainage systems, will be analyzed for interpreting the effect on the interaction between shallow and deep groundwater. The quality of the drainage water will be also interpreted for the evaluation of the salt balance within the soil profile for a given period of time.