Inverse Distance Weighting as an alternative interpolation method to create radiometric maps of natural radionuclide concentrations using QGIS

Abstract. A previous study by the authors illustrated distribution of naturally occurring radionuclides, i.e., potassium (K40), thorium (Th232), and uranium (U238), in sediment Berg River estuary. The also described Delta Underwater Gamma detection System (DUGS) its usage to measure concentrations these natural radionuclides. It proposed a novel radiometric mapping technique with QGIS and, more importantly, highlighted geospatial process through Kernel Density Estimation (KDE) create maps. present used same data similar design but use Inverse Distance Weighted (IDW) interpolation method display radionuclide concentrations. maps created using KDE smooth visually attractive However, IDW is an exact that predicts value at sampling location identical observed value. This requirement for analysis sediments. effectiveness methods was evaluated SPSS statistics software. First, probability-probability (P-P) plots were produced each method. Secondly, descriptive regression statistics, including 'goodness-of-fit', Analysis-of-Variance (ANOVA), coefficients, residuals both methods. done assess which effective calculating (actual vs predicted values) area. results showed experienced problems predict unknown values. consistently performed better than across most tests. Natural radionuclides are useful predictors track sedimentation this paper can serve as benchmark future work tidal non-tidal coastal environments.