中国沿岸海平面上升与海岸灾害

SEA LEVEL RISE AND COASTAL DISASTERSIN CHINA' S COAST

政府间气候变化专门委员会１９９５年气候变化评价报告指出，全球海平面在过去的１００年里上升了１８ｃｍ，预测全球海平面将加速上升，在２０５０年时上升２０ｃｍ，２１００年时上升４９ｃｍ。根据近４０多年的验潮资料分析，中国沿岸海平面上升速率为１．４～２．０ｍｍ／ａ，与全球上升速率一致。由于沿海许多地区的严重地面沉降，地壳垂直升降的不同，以及其它因素的影响，我国沿岸海平面的相对上升各不相同，严重地区的上升速率要大得多。海平面的加速上升必将使我国沿海大部地区的风暴潮等自然灾害更加严重。

ithin the global change problems, most people attention pays to the impacts ofglobal climate warning and sea level rise (SLR) on human society. According to thedocuments of the World Coast Conference (WCC'93, 1993), the 2 / 3 of population in theworld coastal countries will inhabt in coastal are4 where total number will reach 3.7billion. The same as in China, the land areas of coastal Provinces account for a 13.4% ofcountry's total, but the population is over the 40% of total. To the middle of 21st century,when China becomes a middle developed country, about one billion people of China willlive in the coastal area However, the narrow-long belt area with 60 km width offcoastline, i. e. coastal zone (CZ),is the area of most population density and of verydeveloped economy of all the country. Moreover, the economic strength mainly distributedover the areas surrounding Bohai Sea. Changjiang (Yangtze River) Delta and Zhujiang(Pearl River) Delta. These areas not only endure great Pressure from socioeconomicdevelopment but also are very vulnerable to suddenly natural and technological hazards asstorm surges, storm waves, sea ice, tsunamis, red tides (and other biological hazards),marine pollution, marine oil spill etc. and slow events as coastal erosion . bay silting,intrusion of salt water to coastal underwater layer, coastal land salting etc. According tothe international standards abided by the Common Methodology for Assessing Vulnerabilityto Sea Level Rise by Intergovemmental Panel on Climate Change (IPCC) ResponseStrategies Working Group (RSWG) Coastal Zone Management Subgroup (CZMS), the areaof coastal zones with an elevation being not greater than 5 m is the risk zone by sealevel rise. There are 143 900km 2 areas of such type vulnerability along China's coast thatis about 11.5% land area of coastal Provinces. More than 70 million people i.e. 14.9% of population of coastal Provinces are living in the vulnerable zone, that is about 27% ofthat vulnerable areas Of all the World. So, the impact of global sea level rise on theChina's coastal area will be in an all-round way and gravely.The global sea level (GSL) i.e. eustatic sea level namely is the global mean sealevel (GMSL) but no the sea level for a concrete location, that we call as the relativesea level (RSL). According to the Second Assessment Report of the IPCC 1995, theglobal sea level rose by 18 cm during the last 10-years. It is a certain result due to theincreasing of greenhouse gases since the industry revolution and the global climatewarming. The basis of the IPCC 1995 projections of global sea level rise taking intoaccount further changes in aerosol amounts under the IS92a Scenario, the GSL isprojected with optimum to rise by 20cm by the year 2050, with a range of uncertaintyof 7~ 39cm , GSL is estimated to rise 49 cm by the year of 2100, with a range ofuncertainly of 20~86cm.Since the 1960's year, some internal and external experts have studied MSLchange along China's coast. According to that research results the sea level rise ratealong China's coast is about 1.4 mm / a to 3.0 mm / a during the last 40 ~ 50-years.The reason of difference of rise rate is mainly due to the different data that is basedon by different authors. Moreover, more differences for rise rate of relative sea levelon each coastal areas, that the rise rate reaches 9.3 mm / a along the Laizhou Baycoast near by Yangjiaogou City, Shandong Province, 7.2 mm / a~ 4.5 mm / a on coastsfrom Lusi , North Jiangsu Province to Shanghai; and - 1. 3mm / a on the coasts ofShandong Peninsula. The comprehensive data base of MSL and related factors of theChina's coast was made in 1994. On the basis of this data base the analyzes andcalculation were made, and the sea level rise rate is obtained as 1.4 mm / a to 2.0mm / a, or 1.7 ± 0.3 mm / a along the China's coast that is showing no differenceof GSL rise rate. A simple estimate model of MSL change is made by consideringthe accelerate rise of GSL due to greenhouse gases effect and the characteristics ofsea level rise along China's coast and that the se