福建海坛岛地质灾害特征及风险评价

摘要

通过现场调查及历史岸线对比的方法，摸清了海坛岛主要的地质灾害类型及其分布特征，发现海坛岛存在三种地质灾害类型：海岸侵蚀、重力类地质灾害（崩塌与滑坡）与风沙灾害。海岸侵蚀为主要的灾害类型，分布在海坛岛东部的岬湾海岸；其中的一些岸段由于人工护岸工程的修建，延缓了海岸的侵蚀后退，但同时造成临近沙滩的侵蚀退化。崩塌与滑坡共计16处，分布于海岛各处，多半为开山采石等开发活动造成。风沙灾害区位于海坛岛东北部长江澳沿岸，沙源为长江澳沙滩，这与该地直面常年主风向（NNE）有关。建立了海坛岛地质灾害风险评价指标体系，采用专家打分法与层次分析法确定了各评价指标的权值，通过模糊综合评判模型，对海坛岛地质灾害风险进行评价。结果显示，中、高风险区与主要的地质灾害类型的分布区域一致，而岛陆主体为低风险区。根据海坛岛地质灾害特征及风险评价结果，给出了灾害防治建议。%On the basis of field investigation and historical coastline comparison,type and distribution of geo-logical hazard in Haitan Island are analyzed.The results show that there are three types of geological hazard:coast-al erosion,gravitational geological hazard (collapse and landslide)and wind-sand disaster.As the major type coastal erosion happens at the headland-bay coasts situated in the east part of Haitan Island.Due to building of re-vetment dike,beach degradation happens at some coasts.There are 16 collapses and landslides at the steep slopes mostly induced by quarrying activity,which distribute in the coast and land of island.Under the control of annual predominant wind direction (NNE),the area of wind-sand disaster is situated in the northeast part of the island and the sand comes from neighboring beach.Risk assessment of geological hazard is made by fuzzy comprehensive evaluation model.Before that the evaluation index system is confirmed and the weight of each index is calculated by expert scoring method and analytic hierarchy process (AHP).The assessment results show that medium and high risk areas are consistent with the distribution areas of geological hazard.At last the advice on prevention and treat-ment of geological hazard is given.