Study Of Remote Sensing Mornitoring Of Wetland Dynamic Change In Yellow River Drainage Area

The purpose of this study is making use of remote sensing and GIS technique to investigate quantity, type, distribution, change, and cause of wetland in Yellow River Drainage Area. The main content is focused on multiple data processing, wetland classification, wetland information extraction and comprehensive analysis.Data resources consists of 1:500 000 China geological map data base, 1:250000 China terrain map data base, 1:100000 terrain map, 1:500000 China land use data base, DEM of Shuttle Radar Topography Mission(SRTM), MSS(1975),TM(1990)and ETM(2000)acquired by Landsat satellite. These data are consolidated in the same coordinate system through a series of processing including scanning and digitizing of paper map, geometric correction, mosaic and segmentation. Basing on wetland classification method of"The Ramsar Convention on Wetland"and"Regulations of investigating and monitoring of wetland in China", and also according to the practical condition, the wetland of Yellow River Drainage Area are classified into 5 classes in the first level and 15 types in the second level. Wetland temporal information of three stages was extracted by combining computer automatic information extraction and naked-eye and computer aided interpretation. Wetland change information was extracted by using of the technique of geographic space analysis. Basing on statistic result, dynamic characteristic of wetland is summarized。Two factors including nature and human being are considered in the analysis of the cause of wetland change.The innovation and conclusion of this thesis go as follows:1. Forming the scheme of remote sensing mornitoring of Wetland Dynamic Change in Yellow River Drainage Area, and directoring the making of a series of wetland maps including:Wetland map of standard scope in Yellow River Drainage Area (1:250000, 1975, 1990, 2000),Wetland dynamic map of standard scope in Yellow River Drainage Area (1:250000, 1975-1990, 1990-2000),Remote sensing image map of standard scope in Yellow River Drainage Area (1:250000, MSS, TM, ETM),Wetland map in Yellow River Drainage Area (1:1500000, 1975, 1990, 2000), Wetland dynamic map in Yellow River Drainage Area (1:1500000, 1975-1990, 1990-2000),Remote sensing image map in Yellow River Drainage Area (1:1500000, MSS, TM, ETM).These maps are the basis for the comprehensive analysis and evaluation of ecological environment in Yellow River Drainage Area.2. Proposing the method of swamp extraction basing on object-based classification and solving some key issues of information automatic extraction. Basing on the fact that swamp is made up of water, vegetation and soil, object-based method was used to extract wetland. According to the bank feature, edge-extract technique was used to extracted river wetland. Because both of spectral and structural feature of wetland were used, the above information-extract methods got better result, which can decrease workload, promote work efficiency, and be worthy of applying to other area.3. In some extent, clearing such issue as wetland type, amount, distribution, change and cause in Yellow River Drainage Area, and got the first basis data which replenish the blank of the study of Wetland Dynamic Change in the recent 25 years in Yellow River Drainage Area, and the conclution is as follows:(1) Multiple types and disproportionally distributedWetlands are mainly distributed in four regions including source area of Yellow River, Nuoergai area, Yinchuan basin and Yellow River delta area. In the source area of Yellow River, the main type of wetland is tundra, in Nuoergai area the main type of wetland is turf. The Yinchuan basin consists of varies kinds of wetland, especially there are more artificial wetland, and the offing-sea wetland is mainly distributed in Yellow River delta area.(2) Total amount of wetland in Yellow River Drainage Area is 28103.51km~2 in 1975 year, 26703.66 km~2 in 1990 year and 24235.48 km~2 in 2000 year. (3) Wetland composition proportion decreasingly ranks as swamp, river, lake, artificial wetland and sea-offing wetland.(4) From 1975 to 2000, the area of wetland in Yellow River Drainage Area took on decreasing trend. In about 25 years, the total amount of wetland reduced 3868.03 km~2,and the reduced extent from 1990 to 2000 is more than those from 1975 to 1990.(5) The cause of wetland decreasing includes nature and human being, especially the human being factor play an important rule and is worthy of more attention.