In recent, the natural disaster like localized heavy rainfall due to the climate change is increasing. Therefore, it is
important issue that the precise observation of rainfall and accurate spatial distribution of the rainfall for fast recovery
of damaged region. Thus, researches on the use of the radar rainfall data have been performed. But there is a
limitation in the estimation of spatial distribution of rainfall using rain gauge. Accordingly, this study uses the Kriging
method which is a spatial interpolation method, to measure the rainfall field in Namgang river dam basin. The
purpose of this study is to apply KED(Kriging with External Drift) with OK(Ordinary Kriging) and CK(Co-Kriging),
generally used in Korea, to estimate rainfall field and compare each method for evaluate the applicability of each
method. As a result of the quantitative assessment, the OK method using the raingauge only has 0.978 of correlation
coefficient, 0.915 of slope best-fit line, and 0.957 of R2 and shows an excellent result that MAE, RMSE, MSSE, and
MRE are the closest to zero. Then KED and CK are in order of their good results. But the quantitative assessment
alone has limitations in the evaluation of the methods for the precise estimation of the spatial distribution of rainfall.
Thus, it is considered that there is a need to application of more sophisticated methods which can quantify the spatial
distribution and this can be used to compare the similarity of rainfall field.