PHYSICALLY BASED SPA MODELING IN A WEB BASED SPATIAL DECISION SUPPORTING SYSTEM

The first results of the LIFE+ SOILCONSWEB project that aims to combine digital soil mapping, soil modeling, digital soil databases and land assessment to produce,to test and to apply a Spatial Decision Supporting System (S-DSS) are shown. The practical focus of this system is to support (stakeholders) decision on landscapeissues aiming to both the best soil conservation and agricultural land management. The S-DSS system is being developed, tested and applied in an area of about 20,000 hectares in South Italy (Valle Telesina, province of Benevento in the Campania region). The system acknowledge that soils and landscapes have the well recognized "multiple functions" as a fundamental feature. Then it is not surprising that this decision supporting system requires, as fundamental feature, to include and mix many different high quality digital information, engine and processing in order to be successfully applied.Our web-based S-DSS system includes modeling procedures at different level of complexity. Here we present tools calculating soil water/solute balance using Richards' based modeling on benchmark soils of the different 47 soil types. This Soil-Plant-Atmosphere (SPA) modeling is used for different purposes including among others (i) estimate of vineyard water stress (affecting wine quality), (ii) estimate of loss of hydrological soil function due to soil sealing, (iii) soil protective capacity towards groundwater pollution expressed by the outflow/inflow ratio. The SPA model is based on the original desktop based SWAP model (Kroes et al, 2008) and enables to be run "on the fly" through the web S-DSS system. The user at this stage can choose between different options including: area (farm, municipality, district, or just drawing the polygon of interest), crop (olive, grapes, maize, bare soil) and date interval for the simulation run. Others options will be further implemented.The S-DSS system every day acquires spatialized data for the upper boundary condition (rainfall and temperatures to estimate ET0 by the Heargraves model) as input for the SPA model running. Hydraulic properties of each soil horizon of the 47 soil profiles were measured in the laboratory by the Wind's method and estimated through HYPRES PTF. Water retention and hydraulic conductivity relationships were parameterized according to the van Genuchten-Mualem model; lab-derived parameters were scaled to field condition by taking into account the coarse fragment content (from the pedological survey) and the hysteretic field behavior of the soil water retention curve. Initial condition was set to h=-50 cm along the soil profile. The simulation starts the 1st January 2011 to manage uncertainty in initial conditions setting. Examples of outcomes are the soil water storage at different depths, inflow/outflow ratio, ETa/ET0, but many others can be implemented, showing the potentiality of the system to allow different scenarios in many field of interest where the balance of the water in the system soil-plant-atmosphere is required.Then decision makers (individuals, groups of interests and public bodies) can have real-time (or near real-time) access to critical, accurate, complete and up-to-datespatial data/output models held/processed in multiple data stores. The system produce detailed spatial documents, report and maps on a series of questions including agriculture, environment and climate change. The tool is available at www.landconsultingweb.eu/.