【作者】 刘腊美；

【导师】 龙天渝；

【作者基本信息】 重庆大学 ， 城市环境与生态工程， 2009， 博士

【摘要】 氮磷营养盐的含量偏高是水体发生富营养化的基本条件,随着三峡水库的蓄水运行,长江和嘉陵江库区段的水文情势发生明显变化,库区水体潜在的富营养化问题成为人们关注的焦点。在点源污染逐步得到控制的情况下,非点源污染成为库区水环境污染的主要形式。嘉陵江是三峡水库流域面积最大的一级支流,是库区氮磷污染的主要背景输入之一。为改善库区水质,保障库区水环境安全,对嘉陵江流域非点源氮磷污染的时空变化规律和控制措施进行研究具有重要的理论意义和实践价值。由于非点源污染具有随机性、广泛性和潜伏性的特点,研究和控制难度大,运用模型对其产生和输移过程进行数值模拟是目前非点源污染研究的重要手段。本研究在建立嘉陵江流域包含气象、地形地貌、土地利用、土壤类型、植被覆盖以及农业人口、畜禽养殖量等空间和属性环境数据库的基础上,通过引入具有物理机制的半分布式水文模型——SLURP模型,建立了由不同土地利用类型、农村居民生活和畜禽养殖产生的溶解态非点源氮磷污染的年负荷模型;以用于预测多年平均土壤侵蚀量的通用土壤流失方程——RUSLE方程为基础,通过考虑引起流域土壤流失年际变化的水文条件和人类活动因素,提出了能够反映流域输沙量逐年动态变化的新估算方法,建立了流域吸附态非点源氮磷污染年负荷模型。由此构建了嘉陵江流域非点源氮磷污染年负荷模型,并进行了验证。应用所建模型,在GIS平台下,采用空间栅格算法,对1990～2007年嘉陵江流域溶解态和吸附态非点源氮磷污染负荷进行了时空分布模拟,对各种污染来源的贡献率、污染形态、关键“源”区进行了定量分析,并依据分析结果指出了需要重点治理的区域及相应的最佳治理措施。为深入研究陆域产生的非点源氮磷污染进入河道后在受纳水体中的输移转化规律及其对水环境的影响,将非点源氮磷污染负荷动态模型与受纳水体生态动力学模型有机耦合,对嘉陵江重庆主城段的水动力特征、氮磷浓度时空分布和藻类生长情况进行了模拟与分析。论文的主要研究成果为:①首次将SLURP水文模型引入非点源污染的模拟研究中,利用其具有物理机制、适合大型山地流域且以土地利用类型为研究单元的优点,代替大多数非点源污染模型采用的SCS-CN统计经验法,作为嘉陵江流域非点源污染模型的水文子模型,通过参数优化,提高了非点源污染的驱动力——降雨-径流的模拟精度,进而提高了非点源氮磷污染负荷估算的准确性。②鉴于嘉陵江流域水沙量不仅受降雨-径流的影响,还受“长治”水土保持重点工程治理进度的影响,因而不仅呈现大水大沙的现象,还呈现输沙量显著减少的趋势,因而多数非点源污染模型中使用的、用于预测多年平均土壤侵蚀量的美国RUSLE方程不能满足动态研究需要,因此本研究以RUSLE方程为基础,从影响土壤流失年际变化的水文条件和人类活动因素着手,并从泥沙输移路径的角度考虑泥沙输移比的空间分布,提出了能反映流域输沙量逐年动态变化的新估算方法,由此建立了流域吸附态非点源污染动态模型,实现了对流域水土流失、吸附态非点源氮磷污染的时空分布模拟。③在流域输沙量动态模型的建立中,由于研究时段长、研究流域尺度大,对输沙量各影响因子进行全流域逐年动态监测十分困难,考虑输沙量的年际变化主要受降雨-径流水文条件和水土保持措施等土地管理活动的影响,首次提出与地表径流模数和治理时间相关的综合影响因子,并通过因次分析法和二元非线型回归法确定了具体的表达式。④针对嘉陵江水文、气候和地形等特点,构建嘉陵江重庆主城段的生态动力学模型,鉴于水动力条件对藻类生长有明显的影响,在模型中引入了水动力因子,提出了该因子的表达式,并应用实测资料对表达式中的参数进行了率定。将水体的生态动力学模型与前述所建的非点源污染负荷模型耦合,模拟非点源氮磷污染进入河道后的输移转化过程及其对藻类生长的影响。更多还原

【Abstract】 High concentration of total nitrogen (TN) and total phosphorus (TP) are the basic cause of water eutrophication. With the change in hydrological conditions since the impoundment of Three Gorges reservoir, potential issue of eutrophication becomes an important problem to solve. Non-point source of TN and TP pollution become a major potential threat of eutrophication to Three Gorges reservoir under the condition of point source pollution have been controlled gradually. Jialing River is the biggest tributary of the Three Gorges Reservoir, and also one of the biggest implicit inputs of TN and TN pollution to it. To improve water quality and protect water environment in the Three Gorges reservoir area, researches on spatial and temporal changes and control measures of non-point source of TN and TP pollution are of important theoretical significance and practical value.As a result of randomness, intensive and uncertainty characteristics of non-point source pollution,the quantitative research of its load and taking control measures on it are both very difficult. Therefore, simulation study of its production and the transport process by establishing mathematic models is an important method of quantifying non-point source pollution load and evaluating management effectiveness at present. In order to control effectively the non-point source pollution in the Jialing River watershed and improve the reservoir water quality, simulation method was taken to study the tempotal and spatial variation of non-point source pollution of TN and TP as well as its environmetal effect on receiving water. At first, based on the distributed hydrological model SLURP, a model of dissolved non-point source pollution load from land-uses, rural life, livestock and poultry raising was established. Then, a new dynamic estimation methods which can reflect yearly sediment yield change of Jialing River watershed was proposed based on the RUSLE model and by proposing a comprehensive influence factor which can reflect the effect of hydrology condition and human activities on sediment yield as well as by considering the space and time differences of sediment delivery ratio from the aspect of delivery route. Then, a non-point source pollution annual load model of particulate TN and TP of Jialing River watershed was established. On this basis, a dynamic non-point source pollution load model of Jialing River watershed was established by organic coupling of the sub-models in the GIS platform. The established load model has been verified by observation data. By the established model, the temporal and spatial distribution of non-point source TN and TP pollution generated by land-uses, rural living, domestic animal raising, water and soil loss in the Jialing River watershed range from 1990 to 2007. And the contribution rate of pollution from different sources, the pollution form, the key "Contribution Zones" were analysed quantitatively. In terms of results of the analysis, the district with serious pollution needed to put much emphasis on controlling was pointed out and the corresponding best management measures were suggested. In order to study of the transport and conversion feature of non-point source pollution in the receiving water, an ecological dynamic model was combined with the established non-point source pollution load model to form a model system. By the ecological dynamic model, the hydrodynamic characteristics, nitrogen and phosphorus concentration and chlorophyll a concentration in Jialing River in the city zone of Chongqing were simulated and analysised.In this paper, the main research results are as follow:①Introducing SLURP hydrological model for the first time in the simulation study of non-point source pollution to replaces the SCS-CN statistic model which majority of non-point source pollution models used, making use of its advantages of physical mechanism, applicable for large-scale mountain watershed, taking different land-use types as hydrological response unit, through parameters optimization and certification, the simulation accuracy of rainfall runoff which is driving forces of non-point source pollution was increased. As a result, the estimation accuracy of non-point source pollution load was increased.②The annual sediment yield at the watershed outlet was not only influenced by hydrological condition, but also influenced by "the key water and soil conservation project in Yangtse River watershed ". Thus, the annual runoff and sediment yield at the Jialing River outlet not only changed with the precipitation conditon but also to remarkably reduced since the implementation of the project in 1989. So, the RUSLE equation which is generally used to prediction the average annual soil erosion can’t satisfy the study requirement. To solve this problem, a dynamic model of annual sediment yield was proposed based on the RUSLE equation and by introducing a comprehensive influence factor which can reflect the effect of hydrological conditions and human activities on sediment yield as well as by considering the spatial distribution of sediment delivery ratio from the aspect of the delivery route. Based on the proposed dynamic model of sediment yield, the non-point source pollution load model of adsorbed TN and TP was established. Using the established dynamic model, the spatial and temporal distribution of soil erosion, sediment yield and non-point source pollution of adsorbed TN and TP were simulated.③During the establishment of sediment yield dynamic model at the watershed outlet, it was difficult for us to carry out dynamic monitoring of each impact factors in the whole basin, because it was a long time research and was in very large-scale watershed. Taking into account the interannual variability of sediment yield mainly affected by hydrological conditions of rainfall - runoff and underlaying surface changes caused by soil conservation measures, a combined influence factor which is related to surface runoff modulus and the implementation time of the water and soil conservation project was proposed for the first time. Furthermore, its specific expression was determined through dimensional analysis and non-linear regression multianalysis.④According to the features of hydrology, climate and terrain of Jialing River watershed, an ecological dynamic model of Jialing river in city zone of Chongqing was established. In view of the significant effect of hydrodynamic condition on algae growth confirmed by measured data in studied river reach, a hydrodynamic factor was introduced in the ecological dynamic model. The expression of the hydrodynamic factor was proposed and the concrete parameters in the expression were also determined by measured data. The ecological dynamic model was coupled organically with non-point source pollution load model and a model system of non-point source polltuion model which can not only simulate overland non-point source pollution loas but also can assess its environmental effect on receiving water was formed.更多还原