| The lake as one of the most important freshwater resources on the earth has many functions such as aquatic product, irrigation, tune store up, traffic, electric power generation, tour, sustain biodiversity,ecological balance and so on. It is important basis of the sustainable development of economy and people's livelihood in the lake basin area. As the demand of people for the agricultural product increases recently, to raise the agricultural output, many agricultural producers exploit cultivated land massively and employ excessive agricultural chemicals like chemical fertilizer and pesticide, which cause the water quality of surface rivers to get worse and total amount of nitrogen and phosphorus in the reservoir as well as the lake exceed the allowed figure. The eutrophication is serious, which brings potential damage to the environment. Therefore the protecting of the existing supplying water source places and guaranteeing safety of the domestic water become the important topic of current researches, which have the profound practical significance to the Jilin Province lake reservoir's water environmental pollution specially the area source pollution launching the system research.The Songhua Lake basin is located at central south of Jilin Province, which crosses 13 city county areas, approximately taking 22.7% of the entire province total area. Its natural amount of runoff accounts for 81.7% of the total quantity of surface water resources of second Songhua River and occupies 38.7% of the total quantity of surface water resources of the entire province. The quality of ecological environment of the Songhua Lake basin is related to the full play of the entire basin synthesis function. For many years, no overall plan consideration to the ecological protection and the environment as well as the comprehensive development, causes the resources in the basin to be destructed, the ecology to lose balance, the soil erosion to aggravate, sediment entering the lake and the pollutant to increase year by year, and the water pollution to get heavier and heavier. Therefore, this paper use comprehensively kinds of theories and methods, employing the multiple source remote sensing data and taking the remote sensing and the geographic information system as the technical support. With water surveillance data for many years, it is essential to the research for the soil erosion and the eutrophication of lake in the Songhua Lake basin.Until now research for soil erosion has more than 100 years'history, experiencing several stages such as the qualitative description based on the spot investigation, the statistics description based on the locating observation, the process simulation based on the corrode mechanism as well as the application of remote sensing and the geographic information system in the soil erosion. Our country has made wide research for monitoring of the regional soil erosion with the support of modern spatial information technology that take the geographic information system and global positioning system as main content. Our country also carries on the dynamic monitoring of national soil erosion and soil conservation, has quick check regularly on the situation of soil erosion and soil conservation, studies qualitative evaluation model system of soil erosion in China, and establishes management information system of national soil conservation. The eutrophication becomes more and more serious, which has been caused all the countries in the world and some international organizations like UNEP to pay enough attention. They develop the research and exploitation such as mechanism of Lake Eutrophication, controlling factors, evaluation method, ecological model and controlling engineering technology of lake pollution. And some achievement has been got on the process of Lake Eutrophication, harm, source, evaluation method, process simulation of water eutrophication, as well as countermeasures and prevention of eutrophication. Evaluation on the process of eutrophication on objective aspect and describing scientific foundation of prevention are one of scientific and technological problems that demand prompt solution by our nation as well as the hot spot of modern environmental science of water source.This paper collects widely related literature material at home and abroad and extracts and integrates the useful information. Combined with the actual situation of studied region, following studies are mainly carried out.Firstly, the writer studies Songhua Lake basin's actual state of development, carries on the analysis separately between the source pollution in point and area pollution, and makes the contrastive analysis technical progress factor of the point source and the surface source pollution, find out the Songhua Lake basin primary pollution source and the pollution limit factor to make sure the pollution present situation of every research area. The research indicated that the pollution of Songhua Lake basin concentrates in the Songhua Lake sector, the point source, the surface source pollution technical progress factor is biggest in this sector. Songhua Lake is serious effect by Huifa River and Jiaohe River's which in her upstream, that is to say that Huifa River and Jiaohe River are two important sources of pollution of the Songhua Lake,.Huifa River is the No.1 in the industrial pollution source quantity, the waste water total withdrawal and four kind of pollutant total withdrawal. Huifa River is biggest to the Songhua Lake sector's pollution technical progress factor, thus causes the pollution to the entire Songhua Lake basin. The point source of red stone sector to the technical progress factor is the smallest, rural population is the least, the village life pollution which produces is lightest. The chemical fertilizer employment quantity and the outflow quantity all concentrate in the Songhua Lake sector, the nitrogenous fertilizer employment quantity is the highest. By the comparement of point source and the surface source pollution technical progress factor we can get to know that the point source pollution technical progress factor is 21.31%, the surface source pollution technical progress factor is 78.69%.Secondly, carries on the soil erosion monitor using the 3S technology, and carries on the soil erosion quantity using US general soil erosion equation USLE the computation, according to the soil erosion modulus computation soil nutrients outflow quantity, contrastive analysis various districts the reason about the outflow of N, P, to confirm the influencing factor which the definite soil nutrients lose. The findings indicated that the soil erosion of Songhua Lake basin presents the tendency which aggravates gradually from the southeast to the northwest. The lightest is Songhua River source area, the deep erosion concentrates in the Huifa River lake inlet middle area.The entire basin majority is the micro corrosion.The deep erosion area is small and concentration. The average erosion modulus is 1,570.699t/km2·a, the corroded total quantity is 62,680,860t/a, the largest erosion modulus is 7,754.52t/km2·a.In the corroded region, 73% are the micro corroded area, light and the moderate corrosion occupies the corroded area separately 11.5% and 8.35%, above the deep erosion occupies the corroded area 7.15%.From the outflow element angle contrastive analysis, the total nitrogen's outflow quantity is much higher than the total phosphorus. This conclusion is accordance with source of pollution diagnosis result, indicated that in the lake the nitrogen element content is high for the reason that the nitrogen element which leads with the soil erosion. The contrastive analysis from the basin various river systems district, the Songhua River source and Huifa River area's N, P outflow quantity is very high, this result will cause the N,P content increase in which between the Baishan lake district and the Huifa River mouth ,Songhua Lake upstream, aggravating the risk of eutrophication.Thirdly, with numerical simulation model as foundation, TSIm is taken to evaluate water eutrophication of Songhua Lake and to make cause analysis on the research results. From the angle of whole basin, the water quality of Red Stone reservoir is the best, White Mountain reservoir the second, and that of Songhua Lake the worst. From the angle of Songhua Lake basin, many pollutants taken to Huifa River make water quality of upstream of Songhua Lake not as good as that of downstream. The lower is in the lake, the better becomes water quality. The water quality of Fengman reservoir is the best. Eutrophication index of the whole basin is 45.64. Therefore, the degree of eutrophication of Songhua Lake basin is at the middle stage, that of Huifa River the highest and reaching mild eutrophication. Last, on the basis of systematic analysis, countermeasures of prevention to the eutrophication of Songhua Lake are proposed. Prevention measures are put forward from eight aspects to suggest that Huifa River and Jiao River, the two tributaries be mainly regulated. Point source and non-point source should be regulated at the same time. Monitoring stations should be increased to make sure monitoring data is timely and effective.Taking multi-source space information, this paper uses technological method of RS and GIS to establish numerical environment model with raster data as unit. Combining evaluation of soil erosion based on spatial technology and evaluation of eutrophication based on monitoring data, the paper studies ecological environment of water in lake and surrounding basin. This method of study and regional study are innovative. This research is significant to reflect the present situation of soil erosion in Songhua Lake basin and that of eutrophication and it also provides scientific basis for governance of eutrophication in Songhua Lake basin.
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