Study On Assessment Modeling Of Coastal Vulnerability To Erosion And Its Application

The coastal zone is the zone where the land and the sea interact,which is of great value to the economic development of human society and the natural ecological environment.The evolution characteristics of coastal zone systems under the action of external dynamics(such as waves,tide,etc.)are complex,while the increasing superposition of human activities will lead to the further complexity of coastal zone evolution.With the rise of sea level,the reduction of rivers into the sea flux,the increased frequency of storm surges,the strengthening of human coastal reclamation activities,coastal erosion has becoming more and more severe.Domestic studies on coastal erosion mainly focus on the analysis and assessment of the causes and mechanisms.There are few assessments of coastal vulnerability to erosion,and they are all single scale assessments of coastal vulnerability to erosion.Coastal zones are often high-speed economic development areas,in the face of coastal erosion,there is an urgent need for different management policies for coastal erosion vulnerability at different scales.There is currently no clear definition of coastal vulnerability to erosion or even vulnerability,but coastal erosion vulnerability mainly refers to people or things in response,resistance and resilience and adaptability from the effects of coastal erosion.The vulnerability assessment of coastal erosion at different scales can provide coastal management policies for different coastal management and provide scientific support for the formulation of disaster prevention and mitigation policies.Guided by the theoretical basis of Marine Science,Geology,Geography,Disaster,Mathematics,and Fuzzy Mathematics,based on the existing research of coastal vulnerability(coastal vulnerability to erosion),this paper establishes the assessment index systems of local and regional coastal vulnerability to erosion.As for the uncertainty(randomness and fuzziness)in the evaluation process,the fuzzy set theory model and multidimensional gaussian cloud model are selected as the evaluation model.Through field surveys and data collection,the assessment indicator data is obtained.On the basis of full access to assessment indicator data,and based on one of the evaluation principles(availability of data)and rapid development status of Fujian(especially Xiamen city)coast(a large number of artificial coast construction),Xiamen and Fujian were selected as research cases.The assessments of coastal vulnerability to erosion at the local level in Xiamen coast(multidimensional gaussian cloud model)and regional level in Fujian coast(fuzzy set theory model and multidimensional gaussian cloud model)are carried out in order to improve the theory and method system of assessment of coastal vulnerability to erosion.It also provides scientific guidance for coastal disaster reduction and prevention and coastal zone integrated planning at different scales,so as to realize the sustainable development of the coastal zone.The main understandings are as follow:(1)This paper defines coastal erosion vulnerability as: in a certain socio-economic context,the coast vulnerability to damage and the ability to adapt and recover from the effects of coastal erosion.On the basis of the existing research of coastal vulnerability(coastal vulnerability to erosion),regional and local level assessment index systems of coastal vulnerability to erosion are established from three aspects: coastal characteristics,coastal forcing and socio-economic.Both scale index systems focus on the impact of artificial coast construction on coastal vulnerability to erosion.For the first time,coastal buffer capacity is proposed as an assessment of the anti-erosion state of artificial coasts and natural coasts at the local scale,and the artificial coastal ratio,as a reflection of the anti-erosion state of the regional artificial coast,makes up for the lack of emphasis on the impact of artificial coast construction on coastal vulnerability to erosion in the assessment of coastal vulnerability to erosion.(2)Written through the Python program language,the heuristic gaussian transform data grading method is applied to the index data grading process of coastal vulnerability to erosion for the first time.Superior to the standard deviation classification method,the heuristic gaussian transform data grading method is a soft classification and reflects the complex spatial distribution characteristics of the data,which divorces from the traditional(such as standard deviation classification method)"Hard grading" bondage,and is more reasonable science.(3)The multidimensional gaussian cloud model membership function is applied to the index data synthesis process of coastal vulnerability to erosion for the first time,which is a good solution for the uncertainty existing in the evaluation process.Multidimensional gaussian cloud model theory is less modeled,the calculation process is simple,and the information loss of multiple synthetic budgets is reduced,which makes the evaluation results more scientific and reasonable.(4)Comparing the similarities and differences between the index systems on assessment of coastal vulnerability to erosion at different scales,the indexes with complete differences between regional and local indexes are coastal elevation,coastal slope,relative sea-level change and tidal range,and the indexes with no difference at all are average wave height,GDP per capita and general public budget expenditure.Other local and regional indicators are related to each other and there are differences,The above differences are due to different scales on assessment system of coastal vulnerability to erosion,different scales of data availability and accuracy,as well as different scales management needs and other reasons.(5)The results of the multidimensional gaussian cloud model on the assessment of coastal vulnerability to erosion in Fujian and Xiamen show that: 1)result of regional assessment: the high levels of coastal vulnerability to erosion in Fujian are mainly distributed in Fuzhou,Pingtan,Putian,Xianyou,Shishi and Xiamen,which need to be brought to the attention of coastal managers.It is urgent to strengthen the adaptive capacity of these coastal sections to coastal erosion,such as enhancing coastal protection capabilities,carrying out soft protection and ecological shore protection.2)result of local assessment: the high levels of coastal vulnerability to erosion in Xiamen are mainly distributed in the coastal section of Xiamen port to Xinglin seawall(island)and coastal section of Yacht Wharf,the coastal section of the Haicang port and Xinglin westside seawall(outside the island),coastal section of Zengcuoan,Baishi fort,Huangcuo and Guanyinshan(island).The coastal infrastructure protection within coastal setback-line of these coastal sections need to be strengthened and the antierosion capacity of artificial coasts need to be enhanced.To sum up,the theory and method system on assessment of coastal vulnerability to erosion established in this paper is used in case studies of different scales,and the evaluation results are reasonable and reliable,which improves assessment of coastal vulnerability to erosion research in different scales in China,and can provide scientific guidance for coastal disaster reduction and prevention and integrated coastal zone planning at different scales,in order to achieve sustainable development of the coastal zone.