The Soil Conservation Service curve number (SCS-CN) method has been widely used in rainfall-runoff modelling; however, the direct effects of rainfall intensities and duration, which are major factors in hydrological engineering design, on its parameters (initial abstraction ratio (λ) and potential maximum storage (S), the latter is transformed into curve number (CN)) have seldom been studied. In this study, we chose simulated rainfall experiments on runoff plots (30 mm/h, 180 min; 60 mm/h, 90 min; 90 mm/h, 60 min) to obtain synchronized rainfall-runoff data and calculated the parameters using general model fitting and event analysis methods every ten minutes throughout the duration. The results indicate that the parameters changed with rainfall intensities and duration. S decreased as the rainfall intensities increased. Under the same rainfall intensity, the S increased with the duration overall. The corresponding λ changed with rainfall intensities and duration, and has no obvious relationship under different rainfall intensities. Initial abstraction in the event analysis method is the same as the actual situation and we chose these parameters obtained with the event analysis method as our selected parameters. These selected parameters and the parameters obtained using Fu et al.’s method which was based on the standardized procedure in NEH-630 were evaluated by the Nash–Sutcliffe efficiency (NSE), the percentage deviation coefficient (PBIAS), and the ratio of the root mean square error to the standard deviation of measured data (RSR). The results show that the statistics for the selected parameters satisfied the evaluating standard, and have a better value, while the statistics for the parameters obtained by Fu et al.’s method declined as the rainfall intensity increased, and PBAIS was out of the standard range under 90 mm/h rainfall intensity condition. This indicates that the rainfall intensities and duration have important effects on the parameters of the model, and the parameters vary dynamically with the rainfall intensity and duration. These results could be useful for hydrological design in which engineers consider the return period (i.e., rainfall intensities and duration).

中文翻译：

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模拟降雨下降雨强度和持续时间对SCS-CN模型参数的影响

土壤保持服务曲线数（SCS-CN）方法已广泛应用于降雨-径流建模；然而，降雨强度和持续时间是水文工程设计的主要因素，对其参数（初始取水率（λ）和潜在最大蓄水量（S），后者转化为曲线数（CN））的直接影响有很少研究。在本研究中，我们选择了径流样地（30 mm/h，180 min；60 mm/h，90 min；90 mm/h，60 min）上的模拟降雨试验，以获得同步的降雨-径流数据，并使用一般在整个持续时间内每十分钟进行一次模型拟合和事件分析方法。结果表明，参数随降雨强度和持续时间而变化。S随着降雨强度的增加而降低。在相同的降雨强度下，S总体上随着持续时间的增加而增加。相应的λ随降雨强度和持续时间变化，在不同降雨强度下无明显关系。事件分析方法中的初始抽象与实际情况相同，我们选择这些通过事件分析方法获得的参数作为我们选择的参数。这些选定的参数和使用 Fu 等人的方法获得的参数，该方法基于 NEH-630 中的标准化程序，通过纳什-萨特克利夫效率 (NSE)、百分比偏差系数 (PBIAS) 和测量数据标准偏差 (RSR) 的均方根误差。结果表明，所选参数的统计满足评价标准，具有较好的价值，而Fu等人的方法得到的参数统计随着降雨强度的增加而下降，在90 mm/h降雨强度条件下PBAIS超出标准范围。这表明降雨强度和持续时间对模型参数有重要影响，参数随降雨强度和持续时间动态变化。这些结果可用于工程师考虑重现期（即降雨强度和持续时间）的水文设计。参数随降雨强度和持续时间动态变化。这些结果可用于工程师考虑重现期（即降雨强度和持续时间）的水文设计。参数随降雨强度和持续时间动态变化。这些结果可用于工程师考虑重现期（即降雨强度和持续时间）的水文设计。