Accuracy assessment of inverse distance weighting interpolation of groundwater nitrate concentrations in Bavaria (Germany).

ABSTRACT: For the designation of nitrate vulnerable zones under the EU Nitrate Directive, some German federal states use inverse distance weighting (IDW) as interpolation method. Our study quantifies the accuracy of IDW with respect to the designation of areas with a groundwater nitrate concentration above the threshold of 50 mg NO₃/l using a dataset of 5790 groundwater monitoring sites in Bavaria. The results show that the absolute differences of nitrate concentrations between the monitoring sites are only weakly correlated within a range of no more than 0.4 km. The IDW cross-validated nitrate concentration of measurement sites shows a mean absolute error of 7.0 mg NO₃/l and the number of measurement sites above 50 mg NO₃/l is 44% too low by interpolation for all si

SUBMITTER: Ohlert PL 

PROVIDER: S-EPMC9898373 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature