短時間降雨の可能最大降水量(PMP)推定手法に関する基礎的研究

Abstract

In Japan especially in urbanized areas, a heavy rainfall in a short period of time and small area can result in extensive damage. But the probable maximum precipitaion (PMP) for the river basin is not known. The traditional approach to PMP determination is mainly based on the moisture maximization of observed extreme precipitation amounts. However it is known to have a theoretically weak basis. In this study we focus on the heavy rainfall caused by the strong convective cloud. First the traditional approach for PMP is examined and it is suggested that an estimating method using a rainfall simulation model is more useful. Next attempting the one-dimensional convective cloud simulation model developed by Ferrier and Houze, it is found that the parameter of atmospheric moisture (ex. Specific humidity) is very important in estimating the PMP. Finally simulations under several atmospheric conditions show that the traditional approach can underestimate the PMP.