Study On The Landscape Characteristics And Water Quality Of Longhongjian River

As one of the four upstream rivers of West Lake, Longhongjian River is also the natural water supply of it. Along with the development of the social economy and tourism industry, many water environmental issues such as nitrogen pollution become more and more outstanding. The paper is supported by the national key technology and R&D program-"Research about nitrogen and phosphorus removal and eutrophication control technology of urban inland lakes" (2013ZX07310). The study selects Longhongjian River watershed as the study object, aiming for protecting and improving the eco-environment. Main research contents include the analysis of landscape structure and landscape pattern characteristics, the water environment quality, and the response relationship between landscape characteristics and water environment. The main conclusions are as follows:(1) Longhongjian watershed has various types of landscape, such as forests, tea garden, water, building land and urban greening. There has a regulated distribution for landscape structure. And meanwhile for landscape pattern, it exists a high degree of diversity and evenness, aggregation and combination degree, but its fragmentation degree is low. As well as, there are on types of preponderant landscape.(2) The abilities contributing and intercepting pollutants of "source" and "sink" landscapes are expressed by the "source" landscape index and "sink" landscape index. The results revealed that the "sink" landscape index (HI) of Longhongjian watershed is greater than the "source" landscape index (YI), which indicates that the contribution ability of pollutants is better than intercepting ability for this watershed landscape, thus it’s beneficial to reducing pollution. Therefore, the reasonable landscape pattern is conducive to eco-environment in the watershed scale.(3) In general, the water quality of Longhongjian River shows the feature of low-carbon low-phosphorus and high-nitrogen. Obvious spatial-temporal variation also exists in Longhongjian water quality. The water quality changes dramatically over time while it has not significant differences over space. For temporal variation, the pollutant concentration fluctuates by a large margin. Take TN as a example, it varies from 0.80 mg/L to 21.28 mg/L. And for spatial variation, the pollutant concentration changes very little, and the differences mainly distribute in the removal of nitrogen and phosphorus pollutants by the cascade ponds. The results revealed that the removal efficiency of phosphorus pollutants is better than nitrogen pollutants.(4) The water quality of Longhongjian River is evaluated by the fuzzy mathematics model, and the results show that the water quality level of Longhongjian River is inferior than V class in all water periods. And the main pollutant is TN with the weight values of 0.672,0.606,0.653, respectively.(5) The effects produced by landscape structure and landscape pattern on water quality are different. In the landscape scale, Landscape pattern indices can explain some changes of water quality better than the landscape structure indices. And the correlation between water environment and landscape pattern is more apparent than landscape structure.Based on the conclusions above and combined the specific circumstances of Longhongjian River watershed,3 optimization measures are proposed, which can conduce to eco-environment protection and improvement. They are rational division of landscape functional areas, scientific assignment of "source" and "sink" landscape pattern, and strict control of non-point source pollution, respectively.