Case study Flood Frequency Analysis Using Partial Duration Series on Roudsar Polrood River

In all civil engineering tasks such as bridges, roads, dams, in general, and projects related to water resources management in particular, hydrological studies that flood frequency analysis is the important part of it, are always necessary. On the other hand, because of the importance of Polrood river basin in the east of Gilan, frequency analysis of this river has been considered in this study. In this paper, the partial duration series (PD) method which is less considered by the other studies, is used. Three basic assumptions in statistical flood frequency analysis are the independence, Homogeneity and stationarity of the data series. In this paper,158 data is extracted from a period of52 years. Independence of these data is investigated by using the graphical method and also the commonly statistical tests are used for Independence, stationarity and homogeneity. According to Cunnane (1989 ), the annual maximum series (AM) model is statistically more efficient than the PD model when mean number of peaks per year is smaller than 1.65. In this study the mean number of peaks per year included in the PD series is equal to3.04 . The boxcox transformation is used which transforms nonnormally distributed data to a set of data that has approximately normal distribution. At the end of this study, results of the AM and PD models are compared.

کلیدواژه ها:

flood frequency analysis ، independence and stationary ، normal distribution ، partial duration series ، Polrood river