Coupled SVAT–groundwater model for water resources simulation in irrigated alluvial plains

Understanding the interaction between soil, vegetation and atmosphere processes and groundwater dynamics is of paramount importance in water resources planning and management in extensively irrigated alluvial plains. This is the case, for example, of the most important agricultural and industrial area in Italy, the Padana Plain, where intensive exploitation of groundwater for domestic and industrial supply coexists with massive diversions from surface water bodies, providing abundant irrigation to one of the most productive agricultural districts in Europe. The paper presents a simulation system which reproduces the hydrological processes relevant in alluvial irrigated plains. In particular, it allows the evaluation of the distribution of crop water consumption in space and time, as well as simulation of the interaction between recharge and groundwater dynamics. The simulation code is based on the coupling of two models: a conceptual vadose zone model and the groundwater flow model MODFLOW. Additional code was written to provide an interface which performs the explicit coupling in space and time between the two models. A geographical information system (GIS) manages the spatially distributed inputs, parameters and outputs of the system. An application of the package to a large irrigation district, of approximately 700 km2, located in the middle of the Padana Plain, is also discussed in the paper