IDFカーブ 台風14号 L-moment法 適合度 平均信頼度 IDF curve Typhoon 0514 L-moment method goodness-of fit mean of confidence degree
As mentioned in several hydrological textbooks, derivation of IDF (Intensity-Duration-Frequency) curves of rainfall for a region or observation point is one of the first steps in many hydrologic design projects, such as in design of facilities for flood prevention. We used AMeDAS data observed by the Japan Meteorological Agency and tried to improve a method how to construct the IDF curves. We adopted L-moment method for estimating the parameters of statistical distributions. For the evaluation of goodness-of-fit, we used MC (mean of confidence level) as well as SLSC (standard least-squares criterion). We conclude that the MC could be a potential valuable criterion. Moreover, we evaluated the frequency of rainfall depth due to Typhoon 0514. As a result, that is evaluated to be a heavy rainfall whose return period is longer than 120 years.