设计洪峰流量.docVIP

英译汉 7.3 Design Peak Flow Estimation设计洪峰流量Analysis of reports published by the Sierra Leone Roads Authority SLRA identified the Regional Rational Method as most appropriate for predicting peak design flows in Sierra Leone SLRA, 2006 .The Road Drainage Manual 2006 produced by The South African National Roads Agency Limited recommends that the Rational Method be applied to catchment areas smaller than 15 km2. Due to the limited number of methods available for the determination of flood peaks in Sierra Leone, the Rational Method has also been used in catchment areas larger than 15 km2. Intensity Frequency Duration FDI data for determining design rainfall intensities were adapted from design storm profiles published in Climate Studies for Tonkolili, Sierra Leone: Stage 2 – Climate assessment and data analysis UK Met Office, 2010 in combination with daily rainfall records for Freetown. The IFD data adopted for design are presented in Appendix A. 塞拉利昂公路局 SLRA 公布的分析报告中出于Runoff coefficients were estimated using regressions performed on curves found in the Urban Stormwater Management Manual for Malaysia 2000 . These curves relate runoff coefficients to rainfall intensities and soil type, and were considered to be applicable to the Sierra Leone region, in the absence of sufficient information on land/soil conditions. This information can be used to estimate design flows using the Rational Method up to the 50 year ARI event. Flood frequency analysis was performed on extreme flows estimated for various sites in Sierra Leone, published in Lahmeyer International’s Sewa Dam Project report. The results of this flood frequency analysis were used to develop frequency factors, which were applied to Rational Method design flows, to calculate design flows in excess of the 50 year ARI. The frequency factors adopted for design are presented in Table 7-2 Frequency Factors below. 径流系数是通过对马拉西亚城市雨水管理手册（2000）中的曲线进行线性回归来预测的。这些曲线表示的是径流系数与降雨强度和土壤类型之间的关系，在当前关土地/土壤情况的信息不足的条件下，这些曲线应用于塞拉利昂地区