基于SWAT模型的西湖流域非点源污染研究

发布时间：2018-03-05 13:02

本文选题：西湖流域　切入点：龙泓涧　出处：《浙江工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：地表径流是西湖主要的非点源污染源之一。本文采用野外监测、室内分析并与计算机模拟结合的方法,研究了西湖流域不同降雨条件下营养盐的迁移规律,并运用SWAT非点源污染模型对4条主要入湖溪流的氮磷通量进行模拟验证,为西湖流域的非点源污染治理提供理论基础。(1)总磷和总氮的多场降雨径流平均浓度(Site Meancon Centration,SMC)值在中雨、大雨、暴雨及大暴4中雨强下分别为0.24、0.14、0.13、0.19 mg·L-1和5.04、4.59、5.83、5.21mg·L-1。不同雨强下总磷和各形态氮素的SMA(多场降雨径流平均迁移量)值均与雨强表现为正相关,暴雨事件在能产生明显径流的降雨事件中的比例达到32%,且暴雨事件中SMC和SMA值都较高,暴雨的冲刷作用是氮、磷流失的重要作用。(2)径流小区中径流量与降雨量和降雨历时都有很好正相关,相关系数分别达到了0.903和0.786,表现出很好的线性关系。三个径流小区中林地(19?)产沙量的增大最为显著,茶园(5?)的产沙量较之林地很小。茶园的污染物浓度要明显比林地高,总磷和总氮的最高浓度分别达到了3.41和32.86 mg·L-1。对比林地径流小区,茶园小区两次极端降雨事件中总磷、可溶性磷、总氮、硝态氮和氨氮的迁移通量分别占到了总迁移通量的0.58、0.57、0.58、0.54和0.65,茶园的抗侵蚀能力要比没有人为活动的林地差。(3)应用Arc GIS软件对模型所需要的空间数据数字高程图、土地利用图、土壤类型图等文件进行投影转换、合并、切割等处理,利用SPAW、PCPSTAT、DEW、MATLAB编程等软件分别对模型的大气发生器、土壤属性等属性数据库计算,构建了SWAT模型的基础数据库。(4)通SWAT_CUP软件对模型参数进行率定和校准,SWAT模型能够较好的模拟西湖流域非点源污染状况。非点源污染主要发生在雨季,2014-2015两年的月均总氮输出量最大值为3478 kg(7月),月均总磷输出最大值为951 kg(6月),分别占到了全年输出量的20.27%和37.47%,非点源污染主要发生在5-9月。对比4个小流域,金沙涧小流域总氮和总磷的输出通量都是最大的,分别占到总通量的54.89%和42.14%,其它依次为长桥溪龙泓涧赤山泉。综合分析总氮和总磷流失的关键区域,长桥溪小流域和龙泓涧小流域南部为西湖流域非点源污染的关键区域。
[Abstract]:Surface runoff is one of the main non-point source pollution sources in the West Lake. In this paper, the transport law of nutrients under different rainfall conditions in the West Lake basin was studied by field monitoring, indoor analysis and computer simulation. The SWAT non-point source pollution model was used to simulate the nitrogen and phosphorus fluxes of four main lakes, which provided a theoretical basis for the treatment of non-point source pollution in the West Lake Basin. 1) the average rainfall runoff concentrations of total phosphorus and total nitrogen were in moderate rain. Under heavy rain, heavy rain and heavy storm 4, the values of 0.24 ~ 0.14 ~ (0.14) ~ (0.13) ~ (0.19) mg 路L ~ (-1) and 5.04 ~ (4) ~ (4) ~ (9) ~ (-1) ~ 5.83 ~ (-1) ~ (5.21) mg 路L ~ (-1) of total phosphorus and nitrogen were positively correlated with the rainfall intensity, respectively. The ratio of rainstorm events to rainfall events that can produce obvious runoff is 322.The SMC and SMA values of rainstorm events are both high, and the erosion action of rainstorm is nitrogen. There is a good positive correlation between runoff and rainfall and rainfall duration in runoff plot, the correlation coefficient is 0.903 and 0.786respectively, showing a good linear relationship. ) the increase of sediment yield is the most significant. The highest concentrations of total phosphorus and total nitrogen reached 3.41 and 32.86 mg 路L ~ (-1) respectively. The transport fluxes of total nitrogen, nitrate nitrogen and ammonia nitrogen accounted for 0. 58% and 0. 65% of the total transport fluxes, respectively, and the resistance to erosion of tea plantations was lower than that of non-artificial forest land.) the digital elevation map of spatial data needed by the model was obtained by using Arc GIS software, and the total nitrogen, nitrate and ammonia transport fluxes accounted for 0. 58% and 0. 65% of the total transport fluxes, respectively. Land use maps, soil type maps, and other documents are processed by projection conversion, merging, cutting, and so on. The model's atmospheric generators, soil attributes and other attribute databases are calculated by means of SPAWN PCPSTATDEWN MATLAB programming software. The basic database of SWAT model. 4) SWAT_CUP software is used to determine the rate of model parameters and calibrate the model parameters. The SWAT model can well simulate the non-point source pollution in the West Lake basin. The non-point source pollution mainly occurs in the rainy season and the total monthly average of 2014-2015 two years. The maximum value of nitrogen output was 3478 kg (July), and the maximum of monthly average total phosphorus output was 951kg (June), accounting for 20.27% and 37.47% of the annual output, respectively. Non-point source pollution mainly occurred in May and September. Four small watersheds were compared. The output fluxes of total nitrogen and total phosphorus in Jinshajian small watershed are the largest, accounting for 54.89% and 42.14 of the total fluxes respectively, and the other is the red spring of Longhong River in Changqiao River in turn. The key areas of the loss of total nitrogen and total phosphorus are analyzed synthetically. The south of Changqiao River and Longhongjian small watershed is the key area of non-point source pollution in the West Lake basin.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52

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