基于SWAT模型的赤水河流域径流年内分配特征及其对降水的响应研究

[目的]研究赤水河流域径流年内分配的非均匀性变化特征及其对降水的响应情况，为流域水资源的开发利用及防洪治涝等研究提供决策依据。[方法]以赤水河流域中上游为研究区，构建SWAT模型相关数据库并对流域径流进行模拟。以实测逐月径流数据对模型进行率定验证。基于模型输出结果，结合降水/径流集中度和集中期，分析流域径流年内分配特征及其对降水的响应情况。[结果]两个水文站率定期决定系数(R²)与纳什效率系数(Ens)均在0.83以上，验证期R²与Ens均在0.69以上，满足精度要求；流域降水和径流年内分配不均匀性显著，二者变化趋势较为一致，主要集中在6—8月；径流集中度的时空分布受降水集中度影响显著，由于入渗和蒸散作用的影响，前者通常大于后者，但当降水集中度较低时(PCD<0.3),径流集中度不再完全以降水集中度为主导；由于流域径流对降水变化的响应存在滞后性，径流集中期往往大于降水集中期，短期较小幅度的降水量增加对降水集中期影响显著，而对径流集中期影响有限。[结论]降水是引起赤水河流域径流集中度/集中期变化的主导因素，而在不同降水量条件下径流系数的变...

Annual Distribution Characteristics of Chishui River Watershed Runoff and Its Response to Precipitation Based on SWAT Model

[Objective] The variation characteristics of non-uniformity for the distribution of annual runoff of Chishui River and its response to precipitation was analyzed in order to provide a basis for decision-making regarding the development and utilization of water resources and flood control in the upper and middle reaches of the Chishui River basin.[Methods] We constructed a database for the SWAT model to simulate watershed runoff. The model was calibrated and validated with measured monthly runoff data. Model output data were combined with precipitation/runoff concentration degree (PCD/RCD) and concentration period (PCP/RCP), and the characteristics of annual runoff distribution and its response to precipitation were determined.[Results] The coefficient of determination (R²) and Nash-Sutcliffe efficiency coefficient (Ens) values for two hydrological stations were greater than 0.83 for the calibration period, and greater than 0.69 for the validation period, which meet the accuracy requirements. The annual distributions of precipitation and runoff was significantly uneven, and the change trends for the two were relatively consistent, with precipitation and runoff mainly concentrated in June to August. The temporal and spatial distributions of RCD were significantly affected by PCD. Due to infiltration and evapotranspiration, watershed RCD was usually greater than PCD. But when PCD<0.3, RCD was no longer dominated by PCD. Due to the lag in the response of watershed runoff to precipitation changes, RCP was often greater than PCP, and a small, short-term increase in precipitation had a significant impact on PCP, but a limited effect on RCP.[Conclusion] Precipitation was the leading factor causing changes in RCD and RCP in Chishui River watershed. Changes in the runoff coefficient in different periods were the main reason for the different response characteristics of RCD/RCP compared with PCD/PCP.