鄱阳湖乐安江流域非点源磷污染特征研究

发布时间：2018-03-28 21:17

本文选题：乐安江　切入点：径流量　出处：《东南大学》2015年硕士论文

【摘要】：鄱阳湖是我国最大的淡水湖泊,近年来湖体水质下降趋势明显。开展乐安江流域总磷输移研究对鄱阳湖水环境保护与改善具有一定的实际意义。本文以乐安江流域为研究对象,分析了流域总磷浓度时空分布特征,基于HYPE模型模拟了该流域径流与总磷输移过程,估算了总磷输出负荷,探究了不同化肥施用量与降雨条件下的总磷浓度和输出负荷。结合MPI-ESM-LR气候模式,预测了乐安江流域未来15年总磷输出负荷。本文的主要工作和结论如下：(1)2010年10月-2011年8月,乐安江TP浓度随季节变化显著,春季最好,夏季最差。空间上,夏季TP浓度由上游至下游逐渐增加,其他季节无明显变化规律。TP浓度与降雨量变化趋势一致,降雨量较大的7、8月份,TP浓度升高；降雨量较小的2-4月,TP浓度相应减小。TP浓度与耕地面积和城乡用地面积占子流域总面积的比例呈正相关关系,与林地面积和草地面积占子流域总面积的比例呈负相关关系；TP浓度对耕地面积、城乡用地面积及林地面积占子流域面积比例的变化较为敏感。(2)基于1978年1月1日-1986年12月31日的气象和水文数据,构建乐安江流域HYPE径流模型。模型在率定期和验证期都达到了理想的精度。率定期,六个水文站的日径流Ens系数和日确定性系数彤均大于0.80,多年径流相对误差最大为-10.24%。验证期,六个水文站的日径流Ens系数和日确定性系数启均大于0.80,除三都站多年径流相对误差Re达14.53%外,其余站点均小于10%,总体效果较好。(3)在己构建的径流模型基础上,利用HYPE模型模拟流域TP输移过程。模型在监测期表现良好,三个水质监测点纳西效率系数Ens均达0.5以上,相对误差RE最大为16.67%。由模型输出结果估算乐安江流域2010年10月-2011年9月TP输出负荷为926.98t。(4)TP浓度和输出负荷随化肥施用量的增加而增加,但变化幅度不大。TP浓度和输出负荷受降雨量影响较大,降雨量减少20%,TP年平均浓度和年输出负荷分别降低35.6%和48.4%；降雨量增加20%,TP年平均浓度和年输出负荷分别增加37.3%和91.0%。进一步说明降雨-径流因子是引起非点源磷污染的重要因素。(5)未来水质预测结果显示：2020-2035年,乐安江流域TP输出负荷呈波动上升趋势。高排放情景下TP输出负荷最大,低排放情景下最小。
[Abstract]:Poyang Lake is the largest fresh water lake in China. In recent years, the water quality of the lake body has declined obviously. It is of practical significance to study the transport of total phosphorus in the Loan River basin for the protection and improvement of the water environment of Poyang Lake. The temporal and spatial distribution characteristics of total phosphorus concentration in the watershed were analyzed. The runoff and total phosphorus transport processes were simulated based on HYPE model, and the total phosphorus output load was estimated. The total phosphorus concentration and output load under different fertilizer application rates and rainfall conditions were investigated. Combined with MPI-ESM-LR climate model, the total phosphorus output load in the coming 15 years was predicted. The main work and conclusions of this paper are as follows: October 2010 to August 2011. TP concentration in Lean River varies significantly with seasons, the highest in spring and the worst in summer. In space, TP concentration in summer increases gradually from upstream to downstream, and there is no obvious change in other seasons. TP concentration is consistent with rainfall. The concentration of TP increased in August of July, and the concentration of TP decreased in February to April of less rainfall, and there was a positive correlation between the concentration of TP and cultivated land area and the proportion of urban and rural land area to the total area of subbasin. There was a negative correlation between the area of forest land and the proportion of grassland area to the total area of subbasin, and there was a negative correlation between TP concentration and cultivated land area. Based on meteorological and hydrological data from January 1, 1978 to December 31, 1986, the ratio of urban and rural land area and woodland area to sub-watershed area is more sensitive. The HYPE runoff model of Le'an River basin is constructed. The model achieves ideal precision in rate periodic and verification period. The daily runoff Ens coefficient and daily deterministic coefficient of six hydrologic stations are all greater than 0.80, and the maximum relative error of runoff in many years is -10.24. The daily runoff Ens coefficient and the daily deterministic coefficient of the six hydrologic stations are all greater than 0.80, except that the relative runoff error of Sandu station is 14.53%, the other stations are less than 10%, and the overall effect is better. The HYPE model was used to simulate the TP transport process in the watershed. The model performed well during the monitoring period, and the Naxi efficiency coefficient (Ens) of the three water quality monitoring sites was above 0.5. The relative error RE is 16.677.The output load of TP from October 2010 to September 2011 is estimated to be 926.98t.(4)TP concentration and output load increasing with the increase of fertilizer application rate. But the range of change is not big. TP concentration and output load are influenced by rainfall. The annual average concentration and output load of TP decreased by 35.6% and 48.4%, respectively, and the annual average concentration and annual output load increased by 37.3% and 91.0%, respectively. It is further explained that the rainfall runoff factor is the cause of non-point source phosphorus pollution. The future water quality forecast results show that: 2020-2035, The TP output load of Le'an River basin showed a fluctuating upward trend. The TP output load was the largest in the high emission scenario and the smallest in the low emission scenario.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52

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