Driving Forces And Effects Of Wetland Change And Wetland Zoning In Hangzhou Bay

Wetland is one of important living environment of human being, and regarded as an ecological landscape of the most biodiversity in the nature. Wetland ecosystem is significant to state ecological safety and fundamental to sustainable development of economy and society with its functions of climate regulation, water regulation, waste treatment, habitat, food production, recreation, research and education, etc. Wetland protection is important to ecological balance, harmony between nature and human being, and sustainable development of economy and society. However, in recent years, wetland was reclaimed greatly and eco-system was threatened seriously due to many reasons, i. e. undervalue of eco-system, driving on the economic benefits, and the stress of land requirements. Destroying of wetland made great impact on global and regional environment and economy development. So, with the decreasing of wetland and degraded of eco-system, it's significant to harmonize wetland protection and reclamation based on analysis of driving forces and ecological and economic effects of wetland change.Hangzhou Bay abounds in wetland resources, but wetland is reducing greatly by agriculture reclamation and construction land occupying in recently. With increasing land requirements from agriculture, industry, traffic, city and port construction, wetland protection facing grave challenges. The researches on wetland resources survey and protection in this area are deficient at presently. This paper revealed the spatial and temporal characters and driving forces of wetland change and estimated the ecological and economic effects basing on wetland remote sensing survey from 1990's, and then brought forward zoning scheme and regulations, which can be used for reference of wetland protection, layout of industries, wetland research and management.The main contents of this paper are followings:(1) Land use/coverage information was firstly extracted using multi-layer classification techniques based on data preparation of Landsat TM images in 1990, 2000 and 2005. Then, wetland conversions and landscape pattern changes during 15 years were analyzed with GIS, land use/coverage change models and landscape pattern indices.(2) Driving forces of wetland change were revealed qualitatively and quantitatively by analyzing the changes of natural factors and social factors. Effect of distances between residental sites and wetland on wetland change was also discussed.(3) New emergy indices were constructed according to emergy flow of the system to show the ecological and economic output levels, and new models for every ecological and economic system relating to wetland change were built. Input and output levels of the systems were estimated, and then the ecological and economic effects of wetland change from 1990 to 2005 were evaluated.(4) This paper discussed the meaning of Wetland Protection and Reclamation Zoning and the principles, types and criterions of zoning. Then, according to the request for protection and land requirements in the process of economy development, wetlands in Hangzhou Bay were divided into four types, i.e. key protection areas, common protection areas, restricted reclamation areas and temperate reclamation areas.(5) According to different aims of protection and development, different regulations for protection areas and reclamation areas were put forward, safeguard measures such as wetland investigation, compensating for reclamation, environmental impact assessment, planning, concentrated management and legislation, etc. were proposed.Possible innovations:(1) Progress was made in comprehensive wetland research in Hangzhou Bay. Wetland in 2005 and its changes in total amount, increase and decrease in area, conversion with other kinds of land use/coverage, changes in landscape pattern from 1990 to 2005 were analyzed using Landsat TM images. Besides, natural and human driving factors which caused wetland change were discussed.(2) Methods for the research of wetland change effect were improved. The paper built emergy models for every kind of ecological economic system relating to wetland change, and constructed new emergy indices to show the output levels of the system. Results showed that, wetland transformation from 1990 to 2005 in Hangzhou Bay caused economic benefit increasing 2.04×10¹⁰US $ and ecological benefit decreasing 1.64×10⁸ US $.(3) New thought and method were proposed in wetland protection research. This paper put forward the new thought that wetland protection combining with reclamation to harmonize ecology protection and economy development by zoning and regulations. Results showed that, key protection areas and common protection areas were 2.4×10⁴hm² and 8.4×10⁴hm² respectively, restricted reclamation areas and temperate reclamation areas respectively occupied 73.7% and 12.1% of total areas. According to different aims of protection and development in different areas, safeguard measures such as wetland investigation, compensating for reclamation, environmental impact assessment, planning, concentrated management and legislation, etc. were proposed in the end.