| Summary: | We need to discuss that the well-precisely estimate of design rainfalls regarding design high and low water-level of a river is one of the most significant problems. Moreover, we have to consider about to improve the awareness of emergency from disaster for people who live along a river. In this paper, we clarified the non-stationary properties of precipitation by a time series analysis. The sum of trend and period components of each of the 22 meteorological observatories in Hokkaido was shown to have 30％-67％ variance of original series. Next, we decided the optimum probability distribution models of the annual precipitation，the annual maximum daily amount of rainfall and the annual maximum number of days with continuous non-rainfall 11in 17 models by the Standard Least-Squares Criterion. Finally, it was shown that the design rainfall for flood management changes extremely, as a result of the change of the T-year probable hydrological amount and its return period from 1989 to 2004 using the Generalized Extreme value distribution. Especially，the Okhotsk Sea area indicated to decrease the safety factor for flood management. application/pdf journal article
|
|---|