【作者】 罗倩；

【导师】 任理； 彭文启；

【作者基本信息】 中国农业大学 ， 水文学及水资源， 2013， 博士

【摘要】 随着社会经济的快速发展,辽宁太子河流域社会环境、流域河流污染问题日益突出,各类工农业污染源带来的有机污染、重金属、农药等污染物给流域水环境带来重大压力。随着太子河流域对点源污染控制能力的提高和技术的相对成熟,非点源污染已成为影响水环境恶化的主要来源。因此,针对非点源污染特征,开展污染负荷定量化研究,识别污染物来源和关键源区,研究不同水文条件、不同土地利用情况、水土保持措施和农业管理措施等对流域非点源污染负荷的影响,是进行水环境质量评估、风险评价及污染物削减的重要依据,也是有效控制水环境污染、保障用水安全的重要手段。本论文的主要研究内容及结论如下：(1)在详细的实地调查、资料收集和模型比选的基础上,基于SWAT模型(Soil and Water Assessment Tool)建立了太子河流域的分布式非点源污染模型。应用LH-OAT (Latin-Hypercube One-factor-At-a-Time)方法进行了参数的灵敏性分析,筛选并确定了模型中需要率定的相关参数,采用SCE-UA方法分别以河道径流量、输沙量和水质指标为目标变量率定相关参数,确定了模型水文、泥沙和水质参数值。率定期R2均大于0.58,NS大于0.60,验证期R2大于0.45,除南甸站以外NS均大于0.50,河道径流模拟效果较好,泥沙和水质模拟结果符合要求,表明模型在太子河流域适用性较好。(2)开展了太子河流域降水量、地表产水量、泥沙流失量和非点源污染物(总氮TN和总磷TP)入河量的时空动态分析,讨论不同水文年型不同降雨情况下,现状年(2008年)非点源污染物的时空变化规律,及土壤侵蚀的空间分布情况,识别污染关键源区。结果表明：1997～2008年流域年均降水量为92.17亿m3,地表产水量为31.35亿m3,泥沙流失量为229.50万t,TN负荷为17357.43t,TP负荷为7110.91t,流域降水量呈东南向西北减弱的趋势,最大值发生在降水量较大的2005年,TN和TP负荷分别为23030.00t、9346.35t。通过多年模型模拟结果,基本上可以确定太子河流域内非点源污染负荷关键源区是下游地区的灯塔市和辽阳县,氮磷负荷强度空间差异较大,全流域多年平均为13.20kg/hm2和5.41kg/hm2。氮磷负荷的时空分布与降水量关系较大,汛期(6-9月)负荷总量占全年的77.76%和80.00%。(3)分析了现状(2008年)经济、人口、气象等水平下,改进施肥方式(情景1)、减少50%施肥量(情景2)、采用水土保持措施(情景3)、增加城镇地区透水面积(情景4)和设置河岸缓冲带(情景5)不同措施对非点源污染负荷的控制效果。5种情景下泥沙流失总量分别减少1.69%、1.54%、33.84%、4.28%、29.62%,TN负荷总量减少7.41%、28.1%、24.38%、2.79%、28.0%,TP负荷总量减少11.39%、41.77%、37.93%、3.36%、36.49%,现状年的TN平均负荷强度为13.72kg/hm2,5种情景中平均负荷强度分别减少1.02kg/hm2、3.86kg/hm2、3.35kg/hm2、0.29kg/hm2、3.84kg/hm2;现状年的TP平均负荷强度为5.52kg/hm2,5种情景中分别平均负荷强度分别减少0.63kg/hm2.2.30kg/hm2、2.09kg/hm2、0.18kg/hm2.2.01kg/hm2,不同土地利用类型的单位面积负荷均不同程度的减少,情景2、3、5有较好的污染控制效果。(4)采用全国1km网格土地利用数据库(1980s,1995,2000)数据,分析了太子河流域在80年代、90年代土地利用情况的动态变化过程,并进一步研究了土地利用／覆盖变化(land useand land cover change, LUCC)对流域水文水资源和非点源污染的影响。1980s-2000年太子河流域内地类转化主要是在水田、旱地、疏林地、城镇用地和农村居民点用地之间,80年代至90年代中期土地利用变化比90年代后期变化要剧烈。1980s到2000年水田和疏林地减少40.81km2、112.34km2,旱地、农村居民点用地、城镇用地、工交建设用地分别增加113.30km2、16.73km2、19.50km2、10.04km2,水田转化为农村居民点用地、城镇用地和工交建设用地,而疏林地转变为早地。1980s土地利用情况下,1997～2008年多年平均地表产水量、泥沙流失量、TN和TP入河量分别为33.30亿m3、207.80万t、16756.68t和6666.70t,1995年土地利用情况下平均值分别为32.83亿m3、210.74万t、16917.52t和6643.84t,空间差异较大。与2000年土地利用情况下相比,1980s和1995年土地利用情况下地表产水量变化较大区域为观音阁水库上游、观音阁水库库区和下游海城地区,不同子流域的TN、TP污染负荷强度有增有减,总体上是负荷强度高的区域变化率较小。更多还原

【Abstract】 With the rapid development of economy and society, the social and water environment problems of the Taizihe watershed in Liaoning province have become increasingly prominent. Organic pollutants, heavy metal pollutants, pesticide pollutants and other pollutants caused by all kinds of industrial and agricultural pollutions have brought tremendous pressure on the water environment. The water pollution can be divided into two types according to the sources of pollutants in rivers, lakes and reservoirs, which are point source pollution and non-point source (NPS) pollution. With the developing techniques and capabilities to control the point source pollution in the Taizihe watershed, the NPS pollution has an more impact on the water environment and the investigations on controlling NPS pollution become more and more urgent. Thus, according to the characteristics of NPS pollution, we carried out the quantitative study of the NPS pollution and identified the sources of pollutants and critical source area. Then, we assessed the effect and changes of NPS pollution under different hydrological conditions, different land use, different soil and water conservation measures or different agricultural management measures. All of these are important bases for water quality assessment, risk assessment and pollutant reduction, but also are an important tool to assess the effective control of water pollution and water security. The main research contents and results for this study are as follows:(1) After a detailed survey, data collection, model comparison and selection, a distributed NPS pollution stimulation model of the Taizihe watershed was constructed using the SWAT model (Soil and Water Assessment Tool). We applied the LH-OAT (Latin-Hypercube One-factor-At-a-Time) method for parameter sensitivity analysis and sensitivity ranks of parameters for each hydrological region was analyzed, which suggested the important parameters used for calibration. The model was successfully calibrated using the monthly observed data of discharge, sediment and water quality with SCE-UA method. R2was greater than0.58and NS was greater than0.60during the calibration period. Meanwhile, R2was greater than0.45, NS was greater than0.50except the Nandian hydrologic station during the validation period. Good agreement between the simulated and observed discharge, sediment and water quality verified the model’s appropriateness in the Taizihe watershed.(2) The calibrated model was used to make the temporal and spatial dynamic analysis of precipitation, surface water yield, sediment loss and the NPS pollutants (TN and TP), to discuss the spatio-temporal change rule of NPS pollution in different hydrological year, to find out the spatial distribution of soil erosion, and to identify critical pollution source area. Results showed that the average annual precipitation was92.17hundred million cubic meter, surface water yield was3.135billion cubic meter, sediment loss was2.295million ton, TN load was17357.43ton, TP load was7110.91ton from1997to2008. Precipitation of the watershed had a weakening trend from southeast to northwest. Precipitation in the year2005is the maximum; meanwhile, TN and TP loads were maximum,23030.00ton and9346.35ton respectively. On the basis of model simulation results, it could be determined that the Dengta city and Liaoyang county located in the downstream areas were the critical NPS pollution source areas in the Taizihe watershed. Spatially, TN and TP loads differed greatly. The average annual values were13.20kg/hm2and5.41kg/hm2. The spatial and temporal distribution of nitrogen and phosphorus loads had an obvious relationship with the precipitation. The loads of flood season (from June to September) accounted for77.76%and80.00%.(3) The NPS pollution control effect under different measures about improved fertilization method (Scenario1),50%reduction in fertilizer (Scenario2), the use of soil and water conservation measures (Scenario3), an increase in urban permeable area (Scenario4) and set of the riparian buffers (scenario5) were simulated within the current (the year2008) economic situation, demographic structure, meteorological condition and so on. The total amounts of sediment loss were reduced by1.69%,1.54%,33.84%,4.28%and29.62%respectively within5kinds of scenarios. TN loads decreased7.41%,28.1%,24.38%,2.79%and28.0%, TP loads decreased11.39%,41.77%,37.93%,3.36%and36.49%, respectively. The average TN load per unit area was13.72kg/hm2, and was reduced by1.02kg/hm2,3.86kg/hm2,3.35kg/hm2,0.29kg/hm2and3.84kg/hm2in different scenarios. The average TP load per unit area was5.52kg/hm2, and was reduced by0.63kg/hm2,2.30kg/hm2,2.09kg/hm2,0.18kg/hm2and2.01kg/hm2in different scenarios. The pollution loads per unit area under different land use types had different levels of reduction. Scenarios2,3and5had better pollution control effects.(4) With the land use data of the1km grid National Land Use Database (1980s,1995,2000), the dynamic change process of land use in the1980s and1990s in the Taizihe watershed was analyzed. Then, the effect of LUCC (land use/cover change) on watershed hydrology, water resources and NPS pollution was researched. The main land use conversion in the Taizihe watershed during1980s to2000was the translation between paddy field, dry land, open forest land, urban land and rural residential land. The land use changes occurred in the late1990s were more tremendous the changes occurred from the1980s to mid-1990s. The areas of paddy field and open forest were reduced40.81km2and112.34km2from1980s to2000. At the same time, the areas of dry land, rural residential land, urban land and labor construction land were increased113.30km2,16.73km2,19.50km2and10.04km2respectively. The paddy field conversed into rural residential land, urban land or labor construction land, while open forest land conversed into dry land. Under the land use situations of1980s, the average annual values of surface water yield, sediment loss, TN and TP loads from1997to2008were33.30hundred million cubic meter,2.0780million ton,16756.68ton and6666.70ton,32.83hundred million cubic meter,2.1074million ton,16917.52ton and6643.84ton respectively within the situations of1995. Compared to the situation in2000, the regions which had significant changes in surface water yield under the situation in1980s and1995were located in the upstream and reservoir area of Guanyinge reservoir and Haicheng city. The changes of TN or TP pollution loads per unit area in different subbasins were increases or decreases. But generally speaking, the rate of changes in the regions that the pollution loads per unit area were high was smaller.更多还原