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降雨特征对低山丘陵区典型小流域水土流失的影响
张真真1, 单延功1, 郭红丽2, 陈家栋1, 陈霞3, 龚畅1, 徐飞1
1.江苏省水文水资源勘测局南京分局, 江苏 南京 210008;2.江苏省水文水资源勘测局, 江苏 南京 210008;3.江苏省水土保持生态环境监测总站, 江苏 南京 210005
摘要:
[目的] 探究降雨特征对南京市低山丘陵区典型小流域水土流失的影响,为低山丘陵区尺度上产汇流分析及水土保持综合治理提供理论支撑。[方法] 以南京市低山丘陵区桥头小流域为研究对象,利用2015—2018年156场降雨事件的水文泥沙数据,运用K-均值聚类法对降雨类型进行划分,采用LSD多重比较法分析不同雨型的特征,建立主要指标的多元拟合回归方程,探讨不同降雨条件下小流域产流产沙特性。[结果] ①降雨量、30 min最大雨强(I30),降雨侵蚀力是桥头小流域产流产沙的重要影响因素,小流域的156场降雨事件中,主要以降雨量 < 75 mm,I30 < 20 mm/h且径流系数 < 0.2,含沙量 < 1 g/L的水沙特征为主。②降雨类型分为Ⅰ(小雨量、小雨强),Ⅱ(大雨量、中雨强),Ⅲ(中雨量、小雨强),Ⅳ(中雨量、大雨强),Ⅴ(小雨量、中雨强)5种,Ⅰ雨型发生频率最高,Ⅳ雨型发生频次最低。③Ⅱ,Ⅳ雨型的产流产沙能力均高于其他雨型,Ⅲ雨型次之,Ⅰ,Ⅴ雨型最小。Ⅰ,Ⅲ,Ⅴ雨型的产水产沙特性差异不显著。④产沙模数和洪峰流量多元回归方程拟合效果较好,拟合回归系数R2都在0.75以上且通过显著性检验,回归方程可用于相关指标的定量计算。[结论] 降雨量,I30,降雨侵蚀力是桥头小流域产流产沙的重要影响因素;不同雨型的降雨特征差异性显著,Ⅱ,Ⅳ雨型是区域产流产沙的主要雨型;利用多元回归方程可以进行指标定量计算。
关键词:  小流域  水土流失  降雨类型  低山丘陵区
DOI:10.13961/j.cnki.stbctb.2020.04.005
分类号:S157.1
基金项目:国家自然科学基金项目:”黏弹性管道水力瞬变动力学行为及流固耦合机制研究”(51808102)
Effects of Rainfall Characteristics on Soil and Water loss of Small Watershed in Low Mountains and Hills Area
Zhang Zhenzhen1, Shan Yangong1, Guo Hongli2, Chen Jiadong1, Chen Xia3, Gong Chang1, Xu Fei1
1.Nanjing Branch of Jiangsu Hydrological and Water Resources Survey Bureau, Nanjing, Jiangsu 210008, China;2.Jiangsu Hydrological and Water Resources Survey Bureau, Nanjing, Jiangsu 210008, China;3.Jiangsu Soil and Water Conservation Ecological Environment Monitoring General Station, Nanjing, Jiangsu 210005, China
Abstract:
[Objective] The effects of rainfall on soil and water loss of small watershed were analyzed in low mountains and hills area of Naning City in order to provide some theoretical basis for analyzing rainfall-runoff characteristics and managing comprehensively in low hill area. [Methods] Runoff and sediment data from 2015 to 2018, and 156 rainfall events were used in this study. Rainfall events were classified by using K-means clustering algorithm. The characteristics of different rainstorm patterns were analyzed by adopting LSD multiple comparison method. And multiple fitting regression equation of main indicators was established to explore runoff and sediment yield characteristics of small watershed under different rainfall conditions. [Results] ① The precipitation, I30, and rainfall erosion force were the important influence factors of small watershed runoff and sedimentation characteristics. Among 156 flood events in the small watershed, the main characteristics were rainfall < 75 mm, I30 <20 mm/h, the runoff coefficient <0.2, and the sediment concentration < 1 g/L. ② The rainfall events were classified into five rainstorm patterns as pattern Ⅰ (low P, low I30), pattern Ⅱ (high P, medium I30), pattern Ⅲ (medium P, low I30), pattern Ⅳ (medium P, high I30), pattern Ⅴ (low P, medium I30). The frequency of pattern Ⅰ was the highest, while the frequency of pattern Ⅳ was the lowest. ③ The runoff and sediment yield of pattern Ⅱ and pattern Ⅳ were higher than that of other patterns, followed by pattern Ⅲ, and pattern Ⅰ and pattern Ⅴ were the least. There was no obvious difference among the runoff and sedimentation characteristics of pattern Ⅰ, pattern Ⅲ, and pattern Ⅴ. ④ The multiple fitting regression equation of modulus of sediment yield and peak discharge had the best simulating effect. The correlation coefficients (R2) was higher than 0.75 and passed the test of significance. The equation could be used to calculate various indexes quantitatively. [Conclusion] The precipitation, I30, and rainfall erosion force were important influence factors to small watershed runoff and sedimentation characteristics. The rainfall characteristics of different rain patterns were significantly different. Pattern Ⅱ and pattern Ⅳ were the main rainfall pattern causing the runoff of small watersheds. Quantitative indicators could be calculated by multiple regression equation.
Key words:  small watershed  soil erosion  rainstorm patterns  low mountains and hills area