产汇流过程对流域营养物质输出与汇集的影响

发布时间：2018-06-24 04:23

本文选题：产汇流过程 + 实验流域　；参考：《清华大学》2015年硕士论文

【摘要】：《2013年中国环境状况公报》显示,海河、黄河、淮河、辽河等一些流域的水环境状况令人担忧,水体环境的恶化加剧了这些地区本就紧张的水资源局势。非点源污染已经成为水体环境的首要威胁,其中氮、磷又是引起水体富营养化的重要因素。流域营养物质的输出和汇集与降雨产流过程紧密相关,只有从相互作用过程研究入手,才能理解土壤养分流失的机理,揭示营养物质的迁移随降雨径流变化而变化的规律。本研究在北京市怀柔区琉璃河流域内的西台子实验小流域,开展了坡地尺度和流域尺度的水量水质观测实验,并结合美国农业部实验小流域的数据和SWAT水文模型工具,通过实验观测、数据分析和模型模拟,揭示产汇流过程对流域营养物质输出与汇集的影响规律。首先,对坡面降雨径流过程的水样进行采集,分析结果表明:雨水对坡面土壤的冲刷侵蚀作用使得地表产流水中的总氮浓度较雨水升高明显,硝态氮浓度较雨水也有所增大;从不同径流成分输出的氮磷负荷看,随地表径流输出的氮磷负荷大于壤中流输出的氮磷负荷,而地表径流的总氮总磷浓度高于壤中流;土壤水中的硝态氮、总磷浓度明显高于雨水,而氨氮浓度要低于雨水,表明土壤中硝态氮、总磷以淋溶的方式随下渗水流迁移,而氨氮则由于被土壤胶体吸附导致浓度下降;地下水中的总氮累积效应明显。其次,对河道流量及水质进行了检测分析,结合美国农业部实验小流域的数据分析,结果表明,雨强的大小是影响产汇流过程中硝态氮浓度变化的重要因素;利用M(V)曲线分析了小流域氮磷输出的初期效应,降水过程中总磷、氨氮较其他营养物质成分表现出明显的初期效应,不同流域对比结果表明总磷与氨氮(或凯氏氮)在初期效应上的规律基本一致。最后,利用SWAT水文模型模拟分析了琉璃河流域近30年氮磷输出与汇集特点,结果表明不同径流成分输出的硝态氮负荷顺序为壤中流地表径流地下径流,而不同径流中的硝态氮浓度次序为地表径流壤中流地下径流。汛期(6-9月)是氮磷负荷输出的主要时期,而随壤中流和地下径流输出的硝态氮负荷受汛期的影响小于地表径流,汛期对总磷输出的影响大于总氮。
[Abstract]:According to the 2013 China Environmental situation Bulletin, the water environment of Haihe River, Yellow River, Huaihe River, Liaohe River and other watersheds is worrying, and the deterioration of water environment has aggravated the already tense water resources situation in these areas. Non-point source pollution has become the primary threat to water environment, among which nitrogen and phosphorus are important factors of eutrophication. The output and accumulation of nutrients in the watershed are closely related to the process of rainfall runoff. Only through the study of the interaction process can the mechanism of soil nutrient loss be understood and the regularity of nutrient migration changing with the change of rainfall runoff can be revealed. In this study, water and water quality observation experiments on slope scale and watershed scale were carried out in the Xitaizi Experimental small Watershed in Huairou District, Beijing, and combined with the data of USDA experiment small watershed and SWAT hydrological model tool. By means of experimental observation, data analysis and model simulation, the effects of runoff production and confluence on nutrient output and accumulation were revealed. The results showed that the total nitrogen concentration and nitrate nitrogen concentration in runoff were significantly higher than that in Rain Water, and the nitrate concentration was higher than that of Rain Water because of the erosion and erosion of Rain Water to the soil on the slope surface. The results showed that the total nitrogen concentration in the surface water was higher than that in the surface water stream, and the concentration of nitrate nitrogen was also higher than that of Rain Water. According to the nitrogen and phosphorus load output from different runoff components, the nitrogen and phosphorus load output from surface runoff is greater than that from soil flow, and the total nitrogen and phosphorus concentration of surface runoff is higher than that of soil medium flow, and the nitrate nitrogen in soil water is higher than that in soil water, but the total nitrogen and phosphorus concentration in surface runoff is higher than that in soil medium flow. The concentration of total phosphorus was obviously higher than that of Rain Water, but the concentration of ammonia nitrogen was lower than that of Rain Water, which indicated that nitrate nitrogen in soil, total phosphorus migrated with infiltration flow in the form of leaching, while ammonia nitrogen decreased because of adsorption by soil colloid. The accumulation effect of total nitrogen in groundwater is obvious. Secondly, the river discharge and water quality were measured and analyzed, combined with the data of USDA experimental watershed, the results showed that the rain intensity was an important factor affecting the concentration of nitrate in the process of runoff production and confluence. The initial effect of nitrogen and phosphorus output in small watershed was analyzed by means of M (V) curve. The total phosphorus and ammonia nitrogen showed obvious initial effect compared with other nutrients in precipitation process. The results showed that the initial effects of total phosphorus and ammonia nitrogen (or Kjeldahl nitrogen) were basically consistent with each other. Finally, SWAT hydrological model was used to simulate and analyze the characteristics of nitrogen and phosphorus output and accumulation in the last 30 years in the river basin. The results showed that the order of nitrate load of different runoff components was ground runoff. The order of nitrate concentration in different runoff is ground runoff. Flood season (June to September) is the main period of nitrogen and phosphorus load output, and the effect of nitrate nitrogen load with soil flow and underground runoff is less than that of surface runoff, and the effect of flood season on total phosphorus output is greater than total nitrogen.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52

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