China Institute of Water Resources and Hydropower Research, Beijing, 100048, China.
China Research Center on Flood & Drought Disaster Reduction of the Ministry of Water Resources, Beijing, 100038, China.
Environ Monit Assess. 2021 Feb 8;193(3):115. doi: 10.1007/s10661-021-08862-0.
The upper catchment of the Miyun reservoir is an important drinking water source in Beijing. In recent years, researchers have used the soil conservation service curve number (SCS-CN) model to calculate surface runoff for the district. Although the runoff forecasting accuracy was unsatisfactory, the lack of understanding of rainfall processes and their influence on runoff may explain the observed deviations. Our study sought to optimize and assess the SCS-CN model simulation accuracy for the district by proposing an SCS-CN calculation method for each runoff event (CN) based on observation data for 253 rainfall and runoff events from 7 plots in the Miyun Shixia watershed. This study elucidated a significant positive correlation between the ratio of CN and the average SCS-CN (CN), as well as the ratio of the maximum X-minute rainfall amount (P) to the total rainfall amount for each rainfall event (P). Furthermore, a calculation method involving power function equations between CN/CN and P/P was proposed for CN. When X = 5 min and the initial abstraction ratio (λ) = 0.01, the simulation performance of the optimized model was the highest, with a Nash-Sutcliffe efficiency coefficient of 0.791, which was significantly higher than that of the non-optimized SCS-CN model. The simulation performance for bare and cultivated land was higher than that of other land uses, with E values of 0.831 and 0.828, respectively. Future research should focus on improving the prediction accuracy of runoff events resulting from high-intensity and short-duration rainfall events.
密云水库上游集水区是北京市的重要饮用水源。近年来，研究人员已使用土壤保持服务曲线数（SCS-CN）模型来计算该地区的地表径流量。尽管径流预测精度不尽人意，但对降雨过程及其对径流的影响缺乏了解可能解释了观测到的偏差。我们的研究旨在通过提出一种基于 7 个米峪石峡流域测站 253 次降雨和径流事件观测数据的每个径流事件（CN）的 SCS-CN 计算方法，对该地区的 SCS-CN 模型模拟精度进行优化和评估。本研究表明，CN 与平均 SCS-CN（CN）的比值以及每个降雨事件的最大 X 分钟降雨量（P）与总降雨量的比值（P）之间存在显著正相关关系。此外，提出了一种用于计算 CN 的 CN/CN 和 P/P 之间的幂函数方程的计算方法。当 X = 5 分钟且初始抽象率（λ）= 0.01 时，优化模型的模拟性能最高，纳什-苏特克利夫效率系数为 0.791，明显高于非优化 SCS-CN 模型。裸地和耕地的模拟性能均高于其他土地利用类型，E 值分别为 0.831 和 0.828。未来的研究应侧重于提高高强度和短历时降雨事件引起的径流事件的预测精度。
