Assessing the groundwater vulnerability to nitrates and pesticides within the geospatial decision support system LandSupport

This work presents how to assess the groundwater vulnerability to both pesticides and nitrate within the geospatial Decision Support system (s-DSS) of LandSupport, though two new web-based, freely-available dynamical tools, named the pesticide fate tool and nitrate fate tool. The pesticide fate tool is based on the extended transfer function model (TFM-ext), specifically expanded to consider the transport of reactive solutes, i.e., pesticides. The nitrate fate tool is based on the coupling of the ARMOSA model, used to simulate the crop growth dynamics and the consequent nitrate leaching within the most biological active zone (i.e. the rooting depth of the soil) and the TFM-ext model, used to assess the transport of nitrate through the unsaturated zone till the groundwater table depth. The tools leveraged the COMPSs programming framework, that allows to parallelize the execution of multiple model runs. Principal inputs of the tools are: soil physical and hydrological properties, climate, groundwater table depth, type of crops and managements (tillage, irrigation, fertilization, pesticides and residual management). Results are shown through the LandSupport GUI both as coloured maps and cumulative charts, representing the relative concentration of solute arrivals to the water table. The work presents the tool implementations for different case studies across European regions, with different spatial scales and pedo-climatic conditions, as examples of application of the LandSupport s-DSS in supporting the Water, Pesticides and Nitrate directives, demonstrating that it represents a valuable instrument for public authorities, environmental planners, as well as agricultural extension services.