| 不同降雨条件下北运河河岸带类型对径流污染削减效果的影响 |
| 摘要点击 2083 全文点击 755 投稿时间：2021-05-28 修订日期：2021-07-07 |
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| 中文关键词 北运河 沙河水库 河岸带(RBZ) 降雨 径流污染 |
| 英文关键词 North Canal River Shahe Reservoir riparian buffer zone(RBZ) rainfall conditions runoff pollution |
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| 中文摘要 |
| 面源污染对北运河水环境质量的影响日益凸显.以北运河流域沙河水库入库支流南沙河和北沙河的河岸带为研究对象，考察降雨过程中河岸带对径流污染的净化效果.根据北运河流域河岸带结构及植物群落的分布特征，将河岸带分为Ⅰ型河岸带（防洪堤-防洪挡墙-林地-草地）和Ⅱ型河岸带（防洪堤-林地-草地）2种类型.以南沙河北岸（NB）和北沙河南岸（BN）为Ⅰ型河岸带的典型代表，呈现植被总盖度低、边坡"短且陡"、草本层盖度低但多样性高.以南沙河南岸（NN）为Ⅱ型河岸带的典型代表，边坡呈现"长且缓"特点，草本层盖度高（29.16%）但多样性低.在3个河岸带各选择1 km开展河岸带面源污染防控工程试验，结果表明，Ⅰ型河岸带的产流时间更短，所需降雨量更少，径流峰值更大；Ⅱ型河岸带仅在大暴雨条件下产生径流，径流滞留能力更强.在河岸带雨水口设置以砾石和碎石等为主要填料的雨水滞留措施可有效净化径流污染，ρ（NH4+-N）和ρ（NO3--N）低于1.6 mg·L-1，ρ（TN）低于5 mg·L-1，ρ（PO43--P）、ρ（DTP）和ρ（TP）低于1.0 mg·L-1；第二道植草沟可有效降低径流ρ（NH4+-N）.除暴雨和大暴雨条件下，Ⅱ型河岸带对悬浮物（SS）的截留率、N和P污染物的削减效果优于Ⅰ型河岸带，这与河岸带的结构及植被盖度有关.Pearson相关分析结果表明，坡长、坡度、植被盖度和降雨特征是河岸带削减径流SS、COD、N和P污染的主要影响因素. |
| 英文摘要 |
| The impact of non-point source pollution on the water quality of the North Canal River is becoming increasingly prominent. In this study, the riparian buffer zones (RBZ) of the Nansha River and Beisha River, the inlet tributaries of the Shahe Reservoir in the North Canal basin, were selected to investigate the purification effect of riparian buffer zones on runoff pollution during the rainfall process. Two RBZ types, Type I RBZ (levee-flood control retaining wall-woodland-grassland) and Type Ⅱ RBZ (levee-woodland-grassland), were classified by the distribution characteristics of RBZ structure and plant communities in the North Canal River basin. The north bank of the Nansha River (NB) and the south bank of the Beisha River (BN) are typical of Type I RBZ, with low total vegetation cover, "short and steep" slopes, and low herbaceous cover but high diversity. The south bank of the Nansha River (NN) is a typical representative of Type Ⅱ RBZ, with "long and slow" slopes and high herbaceous cover (29.16%) but low diversity. In order to investigate the impacts of rainfall characteristics and RBZ types on the runoff pollutant, a 1 km area in each of the three RBZs was selected to carry out the RBZ non-point source pollution prevention and control engineering trials. The results indicated that Type I RBZ required less time and rainfall to produce runoff and had a greater peak runoff. Type Ⅱ RBZ produced runoff only under heavy rainstorm conditions, with greater runoff retention capacity. Energy dissipation ponds with gravel as the main fillers were set up at the runoff inlets of the RBZ, which effectively reduced runoff pollution. ρ(NH4+-N) and ρ(NO3--N) in the runoff were below 1.6 mg·L-1; ρ(TN) was below 5 mg·L-1; and ρ(PO43-P), ρ(DTP), and ρ(TP) were below 1.0 mg·L-1. The grass ditch of the RBZs effectively reduced ρ(NH4+-N) of the runoff. The retention rate of SS and the reduction effect of pollutants in Type Ⅱ RBZ were better than those in Type I except under heavy rainstorm conditions, which is related to the different RBZ structures and vegetation cover. The correlation analysis results showed that slope length, slope gradient, vegetation cover, and rainfall characteristics were significantly correlated with runoff SS, COD, nitrogen, and phosphorus pollution. |
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