A Comparison of Spatial Interpolation Methods for Regionalizing Maximum Daily Rainfall Data in South Sulawesi, Indonesia

Abstract

The aim of this research is to compare between the Inverse Distance Weighted (IDW) and Ordinary Kriging (OK) interpolation methods for regionalization of areas within the South Sulawesi province based on maximum daily rainfall. The data utilized consists of maximum daily rainfall data from 56 rain stations within the South Sulawesi from 1986 to 2021. The spatial interpolation methods applied include the power 2 IDW, and OK. Various semivariogram models, namely Spherical, Gaussian, and Exponential, are employed within the OK method. The selection of the best method is based on the smallest Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) values. The findings of this research reveal that the optimal method for regionalization of maximum daily rainfall is the OK method with a Gaussian semivariogram model. The RMSE values for this method are 57.45, and the MAE values are 46.49. The results of the spatial interpolation demonstrate that the South Sulawesi is divided into four zones characterized by maximum daily rainfall (in mm) as follows: Zone I: less than 230 mm (Eastern and Southeastern regions), Zone II: 230-260 mm (Northern region), Zone III: 260-280 mm (Western region), and Zone IV: more than 280 mm (Southwestern region).