苏州古城区降雨径流水文水质特征研究

发布时间：2018-03-08 21:43

本文选题：城市非点源污染　切入点：古城区　出处：《苏州科技学院》2015年硕士论文　论文类型：学位论文

【摘要】：随着城市化进程的不断加快,城市不透水地表面积的比例不断扩大,降雨径流逐渐成为城市水环境恶化的主要原因。同时,与传统城市相比,古城区城市用地类型以及污染来源更为复杂,水环境也格外脆弱,加之土地利用紧张,对于城市非点源污染的控制和管理方面具有相当的特殊性和迫切性,不能完全照搬其类型城市的经验,在设计时缺乏理论依据。本文基于苏州市古城区内商业区、现代住宅区、老旧住宅区、交通区、园林旅游区等5种具有代表性的功能区降雨径流中水质监测、降雨径流参数以及颗粒物粒径分析,研究了5种城市功能区具有代表性的路面和屋面降雨径流中污染物的EMC分异、赋存形态以及动态变化特征,重点分析径流中的颗粒物的粒径分布、迁移过程以及影响因素,探讨了污染物的初期冲刷效应,并估算了苏州古城区地表径流年污染负荷。在分析时结合古城区地域特色,总结了苏州古城区非点源污染物特性,为苏州古城区城市地表径流污染负荷的控制和削减提供基础资料和理论依据。论文的主要结论如下所示:(1)降雨径流过程线受城市不同功能区下垫面类型以及降雨过程线影响较大,路面径流过程普遍要滞后于降雨过程线,而屋面径流对于降雨过程的响应较为灵敏;由于受地表碱性物质的影响,古城区降雨径流中pH的变化过程普遍呈倒“U”型;苏州古城区降雨径流中污染状况十分严重,多数降雨事件中不同下垫面类型的降雨径流中TCOD、TN、NH_4~+-N、TP和SS均不同程度的超出地表水环境质量标准和污水综合排放标准,并且在不同降雨情景下,不同城市功能区路面和屋面径流中污染物的变化过程表现出较大的差异。(2)颗粒态污染物是古城区降雨径流中重要输出形态,在降雨初期,径流中颗粒态N占比在整个降雨过程中处于最高水平,并随着降雨历时的延长不断降低。而对于P而言,整个降雨过程中均以颗粒态为主,其占比随降雨历时下降幅度较小。(3)城市不同功能区降雨径流中颗粒物的粒径分布、迁移过程和输出特征存在较大差异,在针对径流污染控制措施的设计阶段需要区别对待;前期晴天数、降雨强度、径流量与粒径分布有显著的相关关系,是影响颗粒物分布的重要因素;颗粒物输出在降雨初期受径流冲刷影响较大,径流量与颗粒物迁移能力的相关性在降雨事件初期30%和后期70%径流体积中出现了明显差异;小于150μm的颗粒物是吸附、富集污染物的主要载体。(4)苏州市古城区降雨径流中污染物的初期冲刷现象较为普遍,大部分降雨事件中,径流中的SS、COD、TN、NH_4~+-N和TP均不同程度的出现了初期冲刷现象。但按照初期冲刷系数b值来看,出现的初期冲刷效应主要为弱冲刷和中等冲刷,并未出现强冲刷的场次降雨,由此表明苏州古城区降雨径流的初期冲刷强度相对来讲不是很高;屋面径流的初期冲刷效应受屋面类型的影响较大,坡屋面的初期冲刷效应要高于平屋面,且屋面坡度越大,初期冲刷强度约为明显;降雨特征参数对于初期冲刷效应的影响较小,大部分降雨特征参数与各项污染物的初期冲刷系数的相关性不够显著,只有SS和TP的初期冲刷系数与部分降雨特征之间的相关性达到显著水平(p0.05)。(5)苏州古城区降雨径流中SS、COD、TN、NH_4~+-N和TP的年污染物负荷分别为1775.85、1782.32、32.08、17.15和8.02t。屋面径流的年污染负荷贡献率要小于路面,但其COD、TN和NH_4~+-N的年污染负荷贡献率仍具有较高的水平,是影响城市水环境的重要因素。
[Abstract]:Along with the development of city, city of impermeable surface area ratio continues to expand, the rainfall runoff has gradually become the main reason of city water environment deterioration. At the same time, compared with the traditional city, city urban land use types and sources of pollution is more complicated, the water environment is particularly fragile, and the land use tension is special the urgency and equivalent to the control and management of city non-point source pollution, can not completely copy the type of city experience, lack of theoretical basis in the design. In this paper, the ancient city of Suzhou City District business district based on modern residential areas, traffic areas of old residential areas, water quality monitoring, the 5 functions of rainfall runoff in typical the garden area tourism, rainfall runoff parameters and particle size analysis, 5 kinds of city function areas representative of the pavement and the roof rainfall runoff pollutants in EMC Different forms and dynamic characteristics, analysis of particles in runoff on the particle size distribution, and the influence factors of the migration process, discusses the first flush effect of pollutants, the ancient city of Suzhou area surface runoff pollution load was estimated. Combined with the geographical characteristics of the ancient city area in the analysis, summarizes the characteristics of non-point source pollutants in Suzhou the ancient city of the District, to provide basic data and theoretical basis for control of Suzhou city urban runoff pollution load and reduction. The main conclusions are as follows: (1) the rainfall runoff hydrograph by different underlying surface types and functions of city rainfall line influence road runoff process generally lagged behind the rainfall process line, and the roof runoff response to rainfall is sensitive; due to the influence of surface alkaline substances, the change process of rainfall runoff in pH City area generally inverted "U" type; Jiangsu State the pollution status of Gucheng District rainfall runoff is very serious, TCOD, rainfall runoff on different underlying surface type most rainfall events in the TN, NH_4~+-N, TP and SS had different degree exceeded the environmental quality standards for surface water and wastewater discharge standards, and in different rainfall scenarios, the change process of pollutants in different functional areas of the city road and the roof runoff showed a greater difference. (2) particulate pollutants is an important form of rainfall runoff in Gucheng District, in the early stage of rainfall, than at the highest level in the process of rainfall runoff accounted for particulate N, and with the rainfall duration decreased. While for P, the whole process of rainfall are the particulate, the proportion with rainfall duration decreased less. (3) particles of city rainfall runoff in different function area of the particle size distribution, migration and output characteristics in different, In the design stage to treat runoff pollution control measures need to be distinguished; early sunny days, rainfall intensity, runoff and particle size distribution have significant correlation, is an important factor affecting the particle size distribution; particle output in the early stage of rainfall runoff influenced by runoff, correlation and particle migration in the rain the event in early 30% and late 70% in the volume of runoff appeared obvious difference; particles less than 150 m is the main carrier of adsorption, pollutant enrichment. (4) first flush Suzhou Gucheng District rainfall runoff pollutants phenomenon is relatively common, most of the rainfall events, runoff in SS, COD, TN, NH_4~+-N and TP were found in different degree first flush phenomenon. But according to the initial erosion coefficient b value, first flush effect appears mainly to weak erosion and moderate erosion, not strong scouring the rainfall, This shows that the Suzhou City area of the initial rainfall runoff erosion intensity is not relatively high; the first flush effect of roof runoff is influenced by the type of roof, sloping roof of the first flush effect is higher than that of the flat roof, and the roof slope is large, the initial scour intensity is about significantly; rainfall characteristic parameters for the initial scouring effect has little effect the most rainfall characteristic parameters and the correlation coefficient of the initial pollutant erosion is not significant correlation between SS and TP, only the first flush part coefficient and rainfall characteristics reached a significant level (P0.05). (5) the ancient city of Suzhou District in runoff SS, COD, TN, NH_4~+-N and TP respectively in pollutant load the contribution of 1775.851782.32,32.08,17.15 and 8.02t. pollution load of roof runoff was less than the road, but the COD, TN and NH_4~+-N pollution load contribution rate still has a higher water Leveling is an important factor affecting the urban water environment.

【学位授予单位】：苏州科技学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52;TU992

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