Monitoring and modeling soil water flow and solute transport processes: A mosaic of experiences to look into future directions

Soil and water provide the media for eco-hydrologic processes and mathematical models of different complexity have been developed for describing these processes. Although progress has been achieved in advancing scientific knowledge on the soil-plant-atmosphere continuum (SPAC) as well as in developing improved monitoring and modeling techniques, difficulties still exist in exploiting these results by decision makers and stakeholders that should plan suitable and effective interventions to protect the ecosystems. Major reasons for that are at least twofold and involve both experimental and modeling issues. Fairly good description of the basic hydrologic processes has been aided at the local experimental level by the availability of accurate measuring techniques and devices, but reliable model predictions on the evolution of hydrologic processes are still difficult to achieve, particularly at the space scales of interest for environmental planning. This talk would review and provide a critical account of some laboratory and field experiments, which represent a valuable basis to throw ourselves toward challenging questions in vadose zone hydrology, such as the “scale-transfer” and model over-parameterization problems, with related problems of parameter non-uniqueness and uncertainty of the simulation. Laboratory experiments on soil cores and columns provide confirmation of theories and enable soil hydraulic characteristics to be identified more accurately. Investigations carried out at plot, transect, and catchment scales provide insights into the hydraulic response of field soils and help in understanding to what extent small-scale measurements provide information about larger scale water flow and solute transport processes