Assessment Of Coastal Vulnerability To Sea-Level Rise: Preliminary Results For The Coastlines Along The Pearl River Mouth

The coastal vulnerability includes natural vulnerability and socioeconomic vulnerability. The paper mainly assesses the natural vulnerability. From the understanding of the conceptual framework for natural vulnerability, the paper analyzes with deep insight into the impacting factors of the natural-system to sea-level change, on the one hand, the coast would be susceptibility to the changes including the short-term sea-level changes such as tide, storm tide, El Nino and the long-term sea-level rise. The overlap of this two changes would increase the coastal natural-system vulnerability. On the other hand, the coastal system's natural adaptive response (resilience and resistance) to sea-level rise would induce or increase the potential risk. The changes of the coastal risk to sea-level rise are related to the coastal environment (geology, geomorphology, coastal height, coastal slope and local ascend and subsidence trend). The coasts with high elevation, steep coastal slope, rocky cliff, and ascending stabilization are considered to be of higher autonomous adaptive capacity, and the lower autonomous adaptive capacity areas generally occur at lower-lying beach areas and delta coasts where coastal slope is low and the crust is descending. Susceptibility and the coastal system's natural adaptation together determine the coastal system's natural vulnerability to biogeophysical effects of sea-level rise.To discuss the natural vulnerability of different coasts to future sea-level rise, the paper selects the coasts along the Pearl River mouth as the studied area. After analyzing the impacting factors of natural vulnerability along the Pearl River mouth, the paper divides the coastline of approximately 412km into 25 15-minute gird cells. For assessment purposes, the six variables including geography, relative sea-level change, average tide range, regional slope, shoreline erosion or accretion rates and tropic cyclone impacting frequency are selected as assessed variables. Once each section of coastline is assigned a risk value for each specific data variable, the costal vulnerability index (C.V.I.) can be useto calculate the natural vulnerability of the areas along the Pearl River mouth. After that, the paper develops a database for assessment of coastal vulnerability to sea-level rises and protracts a 1:2,000,000 vectors CVI map of the coastlines along the Pearl River mouth.The results of the assessment indicate: 1) The coastal natural vulnerability for the shorelines along the Pearl River mouth is shown to be distributing uniformly of which the shorelines of high risk coasts and low risk coasts are close equal, and most coastlines are represented by a moderate risk. 2) Different from the U. S. coastlines where the index of most coasts is dominated by one or two variables, the risk values in Pearl River mouth depend on the weights of several variables. 3) The coasts with the same "coastal environment background" will be assigned different risk values on the basis of the difference of one or between several variables. 4) Special assessment must be conducted in different coasts, especially in the choose of assessing indexes that must do complete study to the physical response of the coastline to sea-level rise. According to the assess result, the coastlines along the Pearl River mouth are classified into five risk parts and fifteen subdivision risk sections. At last, the paper discusses the response of different risk shorelines to sea-level rise.