소유역 및 미계측 유역의 설계홍수량 산정시 Thiessen망의 부적절한 이용에 따른 문제점 및 해결방안 연구

Abstract

Thiessen method has widely been used to estimate areal rainfall on a basin. However, Thiessen method contains some problems by improper use in practice. Therefore, in this study, we analyzed the estimated design flood from Thiessen method on a small or ungaged basin and how the selection or the usage of Thiessen method affects estimating the design flood. Furthermore, we widely searched existing cases whose design flood were estimated with Thiessen method. Among those cases, we selected the cases that might be problematic on the watershed division using the Thiessen method. In order to assess the effect of Thiessen method in estimating design flood, we employed the standard process suggested by the national flood design manual as follows: (1) selecting a weather station that has long record length and is close to an interested watershed; (2) recalculating the design flood with the standard process. The results indicate that the estimated design flood from the standard process is different from the flood with the Thiessen method. This difference results from the selection of the inappropriate use of multiple weather stations following to the theory of the Thiessen method. Finally, the current study advocates the standard design flood estimation process using a single station is better than the inappropriate use of Thiessen method. In addition, when selecting a single weather station, we prioritize the station with long record length and high credibility, which is generally run by Korea Meteorological Administration (KMA).