Synthetic indicators of Costa Criticism – Susceptibility of the coast to erosion

The Erosion Coast Susceptibility Indicator (SI_e) was calculated by analysing and crossing through a weighted spatial analysis, three categories of coastal variables: morphological, evolutionary and anthropogenic pressure. Each of them has been given a different weight, as follows: Morphological Variables 50 %, Evolutionary Variables 40 %, Human Pressure Variables 10 %. SI_e = (morphological Variable Classes)*5+(Evolutive Variable Classes)*4+(Antropic Pressure Classes) From the formula, values are obtained, in a range of 10 to 48, which have been normalised into 5 classes using the Natural Interruptions (Jenks) method. The final classes are Values 10 to 17 (CLASSE 1 – lower susceptibility)Values 18 to 24 (CLASSE 2)Values 25 to 31 (CLASSE 3)Values 32 to 38 (CLASSE 4)Values 39 to 40 (CLASSE 5 – maximum susceptibility) Morphological Variables are given by the combination of parameters: Extent of the beach emerging free from permanent infrastructure (2014); average share of the beach emerged (2012); slope of the submerged beach (2012); The Evolutionary Variables are given by the combination of the parameters: Evolution of the Riva Line over the long term (about 70 years), which identify the points characterised by chronic criticality; Evolution of the Riva Line in the short term (3 years); Lowering of the seabed (2006-2012); Recent subsidence (2011-2016);The anthropic pressure describes the percentage of anthropisation of the coast, calculated in a wide band about 300 m from the shore line towards the hinterland.All parameters are calculated along transects perpendicular to the shoreline, parallel to each other and spaced 10 meters.Detailed descriptions of the procedure of analysis and evaluations made are found in the work: ‘Coastal disusceptibility indicators to erosion and flooding’ marine available online at: https://ambiente.regione.emilia-romagna.it/it/geologia/notizie/notizie-2019/rapporto-supporto-mitigazione-rischi-costieri侵蚀海岸易感性指数（Erosion Coast Susceptibility Indicator，简称SI_e）通过加权空间分析与空间叠加运算，对三类海岸变量——形态变量、演化变量与人为压力变量——进行计算得到。每类变量赋予不同权重：形态变量占50%，演化变量占40%，人为压力变量占10%。计算公式为：SI_e = (形态变量类别得分)×5 + (演化变量类别得分)×4 + (人为压力变量类别得分)。据此公式可得到取值介于10至48之间的计算结果，随后采用自然间断点（Jenks）法将其归一划分为5个等级。最终等级划分如下：10~17为等级1（低易感性）、18~24为等级2、25~31为等级3、32~38为等级4、39~40为等级5（最高易感性）。 形态变量由以下参数组合而成：2014年无永久基础设施遮挡的裸露海滩范围、2012年裸露海滩占比均值、2012年水下海滩坡度。 演化变量由以下参数组合而成：长期（约70年）里瓦线（Riva Line）演化情况（该指标可识别长期处于临界状态的岸段）、短期（3年）里瓦线演化情况、2006-2012年海床蚀低情况、2011-2016年近期地面沉降情况。 人为压力指海岸线向内陆延伸约300米的宽幅岸段内，海岸带被人为开发的占比。 所有参数均沿垂直于海岸线的断面进行计算，各断面相互平行且间距为10米。 相关分析与评估流程的详细说明可参阅在线文献《海岸侵蚀与洪涝易感性指标》，获取链接：https://ambiente.regione.emilia-romagna.it/it/geologia/notizie/notizie-2019/rapporto-supporto-mitigazione-rischi-costieri