Ecological System Health Assessment And Ecological Red Line Zoning Based On Remote Sensing

Coastal Zone is located in the interchange of sea and land, which is an important region of international competition and development by virtue of its rich natural resources and favorable geographical position. Rapid economic development has led to a large loss of coastal wetland, coastal waters eutrophication, fishery resource degradation and sea level rising. Coupled with a series of marine pollution incident, ecosystem structure is changed, function and sustainability is reduced in the coastal zone. Coastal ecological red line zoning helps maintainning the national and regional ecological security and economic community sustainable development, enhancing the ecological function, and improving environmental quality. Its significance is realistic and far-reaching. However, ecological red line as a new thing presented in recent years, the theory connotation and zoning method are both need to be enriched and improved. Currently, detailed study of the ecological red line zoning method is rare and it is also to be further expanded in the fields of coastal zone. This study made a comprehensive diagnosis to the ecological problems based on the Zhejiang coastal ecosystem health assessment using remote sensing technology, and the urgency of Hangzhou Bay ecological red line zoning was determined. Then Hangzhou Bay ecological red line zoning method based on the ecological protective importance theory was established and put into practice. This study was made with a view to provide surppots to the ecological red line supervision of relevant departments of Hangzhou City. The results are as follows:(1)Coastal ecological system health assessment of Zhejiang Province based on remote sensing. Zhejiang coastal ecosystem health and its changes were analyzed separately from three subsystems of land, coastline and waters. Use the product of vigor, organization and resilience from 2001 to 2010 to measure Zhejiang coastal terrestrial ecosystem health. Overall, the health status of the ten years shows a downward trend with the presence of spatial heterogeneity. The average health index is 0.1842 with a range of 0.1260~0.2251. Health status is relatively best in Fenghua, Linhai, Yueqing, Pingyang and Cangnan, and the worst is Hangzhou and Cixi. Using multi-source remote sensing image from 1985 to 1995, from 1995 to 2005 and form 2005 to 2013, the length change and land increasing were evaluated to assess the health of shoreline, and the results show that the average health index is 0.33 with a range of 0~0.92, and the worst part is Cixi. Physical, chemical and biological parameters inversed by remote sensing and spatially outside pressure parameters of 2005, 2007 and 2010 were used to establish in Zhejiang coastal waters ecosystem health assessment model. The results indicate that the average health index is 44.68, 49.23 and 46.26 respectively in 2005, 2007 and 2010. The water ecosystem is in an unhealthy state, but there is subtle improvement. Hangzhou Bay and central and southern coastal waters is poorer and further offshore situation better.(2)According to the coastal ecosystem health assessment results of Zhejiang Province, the ecological problems were diagnosed comprehensively. Combined with the ecological protective status of Hangzhou Bay, take "guide" as a criterion, the Hangzhou Bay ecological red line zoning method was established. The worst area of ecocsystem health is Hangzhou Bay. The threats it faces and ecological consequences are analized from the aspects of vegetation cover, shoreline damage, soil erosion, water pollution and marine disasters. Hangzhou Bay needs delineation ecological red line urgently. Combined with the work and lack of water and soil conservation and environmental protection of Hangzhou Bay, based on the ecological protective importance theory, Hangzhou Bay ecological red line zoning method was established from four aspects of ecological function importance, environmental sensitivity, environmental disaster hazard and developemnet prohibited zone. Twelve factors were selected according to the ecological problems, weighting method was determined as AHP, and ecological protective importance index model was taking as the comprehensive model.(3)Ecology protective importance assessment of Hangzhou Bay. The ecological function importance, ecological sensitivity and environmental disaster hazard of Hangzhou Bay were evaluated. The results show that the the more important areas of ecological function are mainly located near shore area of Haiyan County, Xiaoshan City and Cixi City, and inland area of Pinghu City, Shangyu City and Yuyao City. These areas are mainly coastal wetlands, more vegetation and water distributed areas, such as the Hangzhou Bay National wetland Park, Jiulong Mountain National Forest Park. The more sensitive areas of ecological environment are mainly in the coastline area Pinghu City, Haiyan County, Shangyu City, Yuyao City and Cixi City. These coasts have sandy shoreline, important historic sites and scenic spots distribution with higher background level of environmental constraints not easy to restore after damage. Qiantang River estuary and its adjacent waters have lower biological diversit because of the strong sewage and other outside interference and the habitat is destroyed. Ecological environment is also more sensitive. The more serious environmental disaster areas are mainly distributed in the coastal areas of Cixi, Ningbo, Shangyu, Haiyan, Jiaxing and Northern waters. Mucky silt shoreline distributes in Cixi, affected by natural disasters like storm surge and sea-level rise seriously. Ningbo, Zhoushan and Jiaxing distributed more major coastal ports. More sewage outfalls are near Zhoushan Islands with a high incidence of red tide. Sewage emissions, shipping, oil spills and other marine pollution caused by man-made disasters can not be ignored.(4)The range of Hangzhou Bay ecological red line was determined. The single factor maps were comprehensive superimposed. The comprehensive index was divided for the three levels by natural classification. The highest level for the red line zone, and the prohibited zones were into red line zone directly. Hangzhou Bay Ecological red line zone accounts for 4.23% of the total area, the yellow line area and the green Line area accounts for 63.05% and 33.08% respectively. The red line zones are mainly distributed in Haiyan, Shangyu, Yuyao and Cixi and other coastal areas, and wetland accounted for 26.09%. The sensitive shoreline was mainly in the coastal section of Cixi, Yuyao, accounted for 12.65% of the total shoreline length of Hangzhou Bay. Natural landscape and historical sites are manily Sea coastal defense fort ruins in Zhapu and Zhenhai. The center of Fisheries Resource Conservation is in Wangpan moutain in Pinghu waters.(5)Management of ecological red line zone in Hangzhou Bay. The management should follow the laws of nature, and reflect the principles of natural priority giving full play to the natural resilience of ecosystems. Classification management should be taken to the prohibition zone, important ecological function areas, ecological environmental sensitive areas and environmental disaster hazard zone. According to the spatial distribution of ecological protective importance, regional management demand and ability, the ecological red line zone was divided into two levels as first control area and second control area. At the same time, by means of strengthening the coastal ecological monitoring, establishing red line management platform and ecological compensation, to ensure the ecological red line of Hangzhou Bay real "landing" and the long-term development.