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Publication Metadata only Effectiveness of different spatial interpolators in estimating heavy metal contamination in shallow groundwater: a case study of arsenic contamination in Hanoi, Vietnam(2011-04) Pham Quy Giang; Kanchana Nakhapakorn; กาญจนา นาคะภากร; Achara Ussawarujikulchai; Mahidol University. Faculty of Environment and Resource Studiesin shallow groundwater, (2) generate risk map and compare effectiveness of different spatial interpolation approaches including Kriging, IDW and Radial Basis Function of Geographic Information System (GIS) in estimating arsenic concentration... and the highest concentration was found in lower aquifer. IDW gave the best prediction with an average error (MAPE) of 32.82%. An arsenic risk map was created from the IDW method. The map showed groundwater arsenic contamination and high contaminated areasPublication Open Access Estimation of Effects of Air Pollution on the Corrosion of Historical Buildings in Bangkok(2022) Nuttacha Daengprathum; Rattapon Onchang; Kanchana Nakhapakorn; Ornprapa Robert; Aungsiri Tipayarom; Peter Johann Sturmand meteorological measurement data for 2010-2019 from 26 monitoring stations in Bangkok and its neighborhoods. Applying multiple performance measures, the inverse distance weighting (IDW) method was found to be the most suitable. Predictions of the pollutantItem Metadata only Comparison of Spatial Rainfall Interpolation by Using Statistical Methods at Thailand’s Eastern Coast Basin(2025-01-01) Wimala S.; Jirakajohnkool S.; Konisranukul W.; Nakhapakorn K.; Wimala S.; Mahidol Universityin the Eastern Coast Basin using Geographic Information Systems (GIS), this study aims to compare the accuracy of three statistical interpolation methods: Inverse Distance Weighting (IDW), Kriging, and Co-Kriging. The objective is to determine the most effective... May and October 2017. The IDW, Kriging, and Co-Kriging techniques were implemented using GIS-based analysis. The performance of these methods was evaluated using statistical validation metrics, including Mean Absolute Error (MAE) and Root Mean SquareItem Metadata only Comparing Areal Rainfall Estimation Methods in the Ayung Watershed, Bali, Indonesia: A Comprehensive Analysis(2024-01-01) Dharmayasa I.G.N.P.; Putri P.I.D.; Sugiana I.P.; Jindal R.; Surakit K.; Thongdara R.; Dharmayasa I.G.N.P.; Mahidol University, and infrastructure design. Three methods are evaluated: arithmetic average, Thiessen polygon, and Inverse Distance Weighting (IDW). Rainfall data from eight stations across the watershed (2004-2018) reveals a distinct wet-dry season pattern. All three methods yielded... consistent results for areal rainfall estimation, with IDW showing a slight advantage in accuracy. However, the arithmetic average method offers a simpler and faster computational approach, making it suitable for initial analyses. Spatial interpolationItem Metadata only Numerical analysis of volatile organic compounds concentration and evaluation of hazard index in Bangkok, Thailand(Mahidol University. Mahidol University Library and Knowledge Center, 2023) Wisit Thongkum; Natchanok Pala-En; Sarawut Thepanondh; Sopa Chinwetkitvanich; Wanida Jinsartconcentration of all air toxic compounds except 1,3-butadiene. Three different spatial interpolation techniques namely, ordinary kriging, the inverse distance weighted (IDW), and spline were tested in order to find the most appropriate scheme to provide the best... interpolated results for this study. A cross validation and several statistical parameters were employed for selection. Results indicated that in general, IDW performs much better than the other techniques. The impact zone was defined as an area having annualItem Metadata only Variability and distribution of salinity and sodicity levels in fine-textured soils adjacent to brine shrimp farming in inland freshwater areas of Thailand(2025-05-01) Sonsri K.; Poolsab P.; Phankamolsil Y.; Phankamolsil N.; Sonsri K.; Mahidol Universityto determine soil salinity levels upon electrical conductivity (ECe), and soil sodicity levels upon sodium adsorption ratio (SAR). The spatial distribution of soil salinity and sodicity levels was estimated using inverse distance weighting (IDW) technique.... The results revealed that soil ECe values at various depths collected from two periods varied from 0.18-13.63 dS m-1 ( x ˜ = 2.06 dS m-1). Spatial distribution of salinity levels based on IDW estimation exhibited similar patterns among soil depths in bothPublication Metadata only A comparison of spatial interpolation methods for surface temperature in Thailand(2013-12-01) Panudda Tiengrod; Waranyu Wongseree; Mahidol University. Inverse distance weighting (IDW) and ordinary kriging (OK) were used to interpolate surface temperature. Leave-one-out cross-validation (LOOCV) had been use to analyze the spatial error of interpolated data. The result of a Wilcoxon signed rank testPublication Metadata only Proximity analysis of air pollution exposure and its potential risk(2011-05-01) Sarawut Thepanondh; Wassana Toruksa; Mahidol University; Ministry of Natural Resources and Environmentpredicted and spatially interpolated using various interpolation techniques (i.e. kriging, IDW and spline). Sensitivity analysis was carried out to assure the accuracy of the predicted results. The GIS-based exposure map was simulated and was assistedPublication Open Access The Use of geoinformatics for estimating soil organic(2014-06) Prapeut Kerdsueb; Piyakarn Teartisup; ประพฤติ เกิดสืบ; ปิยะกาญจน์ เที้ยธิทรัพย์; Mahidol University. Faculty of Environment and Resource StudiesLANDSAT TM 5; band 1-3-4 was used to predict soil organic matter contents in central plain of Thailand: Nakhon Pathom province as a representative area. There were 135 plots from several agricultural land use; paddy fields, sugarcane and fruit orchard. Y=3.926+0.0176 X1-0.0117 X3+0.0476 X4 (R2=0.357) was the result from the interpolation method at RMSE=0.95. The soil organic matter map was build up via Geoinformatics techniques with additional data sources. These techniques include organic matter models and qualitative methods. Finally, validation methods used to assess the accuracy of maps produced with image data are discussed. It is concluded that a general lack of validation data is a main concern. Validation is of utmost importance to achieve regional operational monitoring systems, and close collaboration between the image data and field-based soil scientists is therefore required.Item Metadata only Estimation of Effects of Air Pollution on the Corrosion of Historical Buildings in Bangkok(2022-09-01) Daengprathum N.; Onchang R.; Nakhapakorn K.; Robert O.; Tipayarom A.; Sturm P.J.; Mahidol Universityand meteorological measurement data for 2010-2019 from 26 monitoring stations in Bangkok and its neighborhoods. Applying multiple performance measures, the inverse distance weighting (IDW) method was found to be the most suitable. Predictions of the pollutant