Regional-scale leaching assessments for Tenerife: Effect of data uncertainties

This paper reports assessments of nonpoint-source (NPS) ground water vulner ability due to pesticide leaching for the Canary Island of Tenerife. Index- based estimates of contamination potential were made for the pesticides Car bofuran and Ethoprophos using the attenuation and retardation factors (AF a nd RF). The major objective of this effort was to characterize the data-rel ated uncertainties, using first-order uncertainty analysis; that are associ ated with the new pesticide Leaching estimates for Tenerife. The crop, rech arge, and soils data for Tenerife were overlaid in this regional-scale stud y using a geographic information system approach. The strategy was to ident ify the effect of supplemental information in reducing uncertainties in the island-wide vulnerability estimates. Data improvements were estimated as r eductions in the AF and RF input parameter uncertainties. The greatest impr ovements in the Tenerife vulnerability estimates were found for reductions in the chemical data uncertainties. The new vulnerability assessments for T enerife will be useful for future agrochemical regulation decisions and for targeting critical areas that may require remediation.