COMPARISON OF SPATIAL INTERPOLATION METHODS IN CONSTRUCTING WATER QUALITY MAPS OF TIEN RIVER FOR INTENSIVE CATFISH CULTURE

Abstract

The application of GIS in water quality mapping has been commonly applied in recent years. However, there is no specific assessment for the application of the appropriate interpolation algorithm for the construction of water quality maps in Tien River belonging to the Mekong Delta. This paper compared and evaluated the usability of two common spatial interpolation methods, namely IDW, RBF and Kriging, on 11 water quality parameters, including temperature, pH, conductivity, alkalinity, dissolved oxygen, total suspended solid, COD, nitrite, TAN, phosphate and total Aeromonas bacteria at 15 monitoring points with 42 sampling periods from 2020 to 2021. Willmott's index of agreement was used for the assessment of results. The results show that there was no statistically significant difference between the two spatial interpolation methods on the study area (p > 0.05). The location, water quality parameters affected the results of three spatial interpolation methods. The average results of three spatial interpolation methods (IDW, RBF and Kriging) were 0.72 ± 0.18, 0.70 ± 0.18 and 0.71 ± 0.17, respectively. IDW can be considered as a preferred choice to interpolate water quality parameters on the study area.