Comparison of interpolation methods in the production of rainfall-induced soil erosion maps in the urban area of Torres Novas, Portugal

Abstract. The evaluation of rainfall-induced soil erosion risk is fundamental for territorial planning and takes into account parameters such as rainfall erosivity, soil erodibility and the topographic factor. The Triangular Irregular Network (TIN) is the most frequently used interpolator in the production of digital elevation models (DEM) but is considered unsuitable by several authors for the calculation of soil erosion. Therefore, the DEM created for the city of Torres Novas, Portugal, using interpolation methods such as Inverse Distance Weighting, Ordinary Kriging, and Empirical Bayesian Kriging (EBK) were evaluated to determine which one was the most accurate. The best interpolator was EBK, from which a rainfall-induced soil erosion map was created. A map was also produced from TIN and both were compared with historical cartography. The EBK method was found to be the most effective interpolator for rainfall-induced soil erosion as well. Therefore, the authors recommend its use in future studies in the municipality of Torres Novas.