نوع مقاله : مقاله پژوهشی
موضوعات
عنوان مقاله English
نویسندگان English
For the design of river bridges and determining their length and height, it is necessary to determine the maximum flood discharge. The most appropriate method for determining the design discharge is the frequency analysis of data from hydrometric stations. One of the characteristics of the data used to ensure that their frequency analysis leads to reliable results is the adequacy of data.The role of statistical period length and number of data on maximum peak flood discharge with different return periods at four hydrometric stations located in the same region in the central Iranian watershed has been investigated. The effect of the length of the statistical period on the results of the discharge-area relationship, the empirical relationship, and the regional flood frequency analysis method at the Shoor watercourse bridge, which is located in the studied area and does not have a hydrometric station on the mentioned watercourse, has been evaluated. The results showed that by increasing the length of the statistical period from 25 years to 44 years, the best fitted statistical distribution on the maximum instantaneous discharges changed and in all four stations, the log-Pearson Type III (LP3) distribution had the most appropriate fit. Also, increasing the statistical length did not have much effect on the values of the maximum 100-year flood discharge at the bridge site studied using the discharge-area method, but in the Fuller empirical method, whose coefficient was calibrated based on the statistics of hydrometric stations, it showed a 9% decrease in discharge. In the regional flood frequency analysis method, which is more accurate for estimating floods in ungauged basins, the discharge values based on the 25-year and 44-year statistical periods were estimated to be 842 and 715 m3/s, respectively, which indicates an increase of approximately 18% in the design flood when using a shorter statistical period.
کلیدواژهها English
