The soil depth is an important factor for assessing the risk of debris flow, and thus, it is necessary to obtain reliable value of area. The objective of this study is to suggest the method for deducing highly reliable soil depth modeling in target area through measured data. The seismic survey as a non-destructive method is selected to predict the soil depth based on reference velocity. The reliability is assessed through mathematical function and error ratio, and the range of reliability is determined from 10% to 90%. The outlier data is removed with consideration of the reliability range and then the soil depth modeling is finalized. The geostatistical method is applied to construct the model. The study implies that the suggested method may provide better resolution than immediately applied method of measured values because of eliminating outlier results. Keywords: Reliability, Outlier Analysis, Geostatistical Method, Seismic Survey, Soil Depth