| 其他摘要 | Coastal vulnerability research is of great importance to sustainable development of our nation’s coastal zone. The coastal area of Bohai Rim in norther China is the typical vulberable coastal region with various types of coastal geomophology, shoreline, and wetlands. In this paper, remote sensing data, geography information and ground survey collection information are integrated using GIS and RS techniques to research the vulberability of Bohai rim coastal zone under the impact of sea level rising due to climate and human activies according to framework of coastal vulverability assessment, the spatilal pattern of vunerbility, shoreline change trends in the past few decades especially in important parts, the flood risk due to storm surges in the future are implemented in the coast zone of Bohai rim to support the integrated management of coast zone (ICZM) and sustainable development of coastal resources and environment. The main contents of this paper are as follows: 1. The comprehensive assessment of coastal vulnerability is the foundation for deep analysis of vulnerability in one area. To get the spatial pattern of coast zone in Bohai rim, we adopt several variables of rock type, coastal slope, geomoporlogy, shoreline change rates, relative sea level rising, mean wave height and mean tidal range to calculate the Coastal vulnerability Index (CVI) in 479 grids with three different combinations. Though the comparison between the statistical results of different vulnerability classes we found that there are 71% similarity between CVI6a and CVI7 (340 grid cells), 75% similiarity between CVI6a and CVI6b (359 girds cells), 93% similiarity between CVI7 and CVI6b (445 grid cells), implying that rock type is more suitable for coast vulnerability index than shoreline change, the apparent vulnerability pattern of Bohai coast remains the same when using different ways of CVI calculation. CVI can effecitvily portray the comprehensive spatical pattern of coastal vulberability and increasing the number of variables or substitute the shoreline change with rock type can increase the distinguish ablility of CVI, but the general spatial pattern of vulberabity in Bohai rim remain almost the same. In general, the up-lift zone of Jiliao and Daxinganling-Taihang hilly rockbed coast have relative low vulnerability while the subsidence zone of Liaohe estuary in Liaodong bay, Bohai bay-Yellow River delta-south bank of Laizhou bay in Bohai-Huabei low plain coast have relative high vulnerability. High vulnerable coast region can be effectively identified using CVI method based on grid presentation, and the variable used to calculated CVI are representing the relative degree of coastal vulnerability under the impact of climate change and sea level rising. The results of this part could help coast managers to identify vulnerable region in coast area and to relieve the stresses of coast environment, it could also help further vulnerability assessment of coast zone. 2. Shoreline change in the past period record important information about coast environment change, and shoreline changes in Bohai rim is one of the important indicators to reveal coastal vulneriblity under climate change. Based on maps and remote sensing images of this region, shoreline changes of 1960 to 2010 are studied. Result showed that, from 1960-2010, the total length of coastline increased 903.5 km, the natural compostion of coastline is muddy shoreline, accounting above 59%， while the length of sandy shoreline accounting 26%-30%, and rocky shoreline about 10-13%, and man-made shoreline were continuously increasing, from 12% in 1960 to 77% in 2010. The coast exploiration before 90s was dominated by salina, and fishery cultivation gradually replace salina aafter 90s, in 2000, harbor construction and land reclamation increased, and became the most import exploiarion formation in 2010, this reflects the impact of human coast exploiraton activities on the variation of coastline compositon. The statistical result of shoreline change revealed that, from 1960-2010, the average shoreline change rate is 37.86 m/yr, the propotion of advance coast (72%) is much higher than the retreat coast (28%). The average shoreline change rate of Laizhou bay is 12.85 m/yr, the propotion of retreat coast is 48%, with an average retreat rate of -21.39 m/yr, the propotion of advance coast is 52%, with an average avance rate of 45.04 m/yr; the average shoreline change rate of Yellow River delta is 56.91 m/yr, with an average retreat rate and advance rate of -36.15 and 94.32 m/yr, the propotion of advance coast (71%) is higher than retreat coast (29%); the average shoreline change rate of Bohai bay is 71.27 m/yr, with an average retreat and advance rate of -17.63 and 79.90 m/yr, the propotion of advance coast (91%) is much higher than the retreat coast (9%); the average shoreline change rate of Liaodong bay is 28.57 m/yr, with an average retreate rate and advance rate of -5.86 and 42.56 m/yr, the proportion of advance coast is also higher than the retreat coast. So the shoreline change of Bohai coast in the past 5 decades is mainly dominated by an advance trend, which mainly attribute with growing human activities. The shoreline change research in this paper revealed the impacts of various natural environmental processes especially human activities on Bohai coast, it may provide scientific support and evidence for proper coastline manament and utilization as well as shoreline erosion disaster prevention to improve the sustainability of coast region. 3. The flood risk of storm surges due to sea level change of climge changing is increasing and flood analysis is one of key components of coastal vulnerability research. The GIS elevation area method was used in this study to simulate the flooded result of land use and land cover for Bohai coast. With sea level rising, under the impact of storm surging with a return period of 10 years, by 2050 the southern coast of Bohai bay mainly Huanghua of Hebei province and Caofeidian in northern Bohai bay would be flooded, with an area accounting about 2%, by 2100 the southern Laizhou bay would be flooded with an area accounting for 4%; under the impact of storm surging with a return period of 50 years, by 2050 most of the Bohai bay would be affected, and south Laizhou bay to Yellow river delta would be flooded, with an area accounting for 13%, by 2100 most region of Bohai coast and eastern frontier region of Laizou bay, south Laizhou bay and Yellow River delta as well Liaohe estuary would be flooded, with an area of 25%, by 2100 almost 1/3 of the Bohai coast within 30 km from shoreline would be flooded. The works r could not only provide scientific support for storm surge vulnerability research cases of Bohai coast, but also could relief the flood risk and improve coast protection as well as land resource management and coast sustainable development. Key Words: GIS; RS; coastal vulnerability; vulnerability index; shoreline change; storm surge. |
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