Coastal Risk Assessment: the Ancona littoral case study
Chiara Vicini, Stefania Mandrone
ISPRA (Institute for Environmental Protection and Research)
The objective of this contribution is to adopt an indicator-based approach to evaluate the coastal vulnerability to sea level rise in Ancona territory. The methodology assesses the indicators that describe the current and future physical sensitivity, in the study area, to coastal erosion and flooding based on the development of numerical indices. According to the project EUROSION, Coastal Risk Index is the product of two parameters: the Coastal Sensitivity Index and the Coastal Vulnerability Index.
The radius of influence of coastal erosion and flooding, RICE, for the purpose of the project, has been defined as all terrestrial areas located within 500 meters from the shoreline, is defined as :
- all areas within 500 m from the coastline
- extended to areas lying under 5 meter.
Within the RICE area identified, some indicators are used for the characterization of coastal risks, understood not only as a probability of occurrence of an event harmful to humans and to environmental resources, but as a parameter, according to the following equation:
RC = ISC * IVC
The result of the previous equation don’t express numerically the expected damage, but it is a quantitative assessment of the presence of causal factors of events at potential risks for coast at local level, for every selected Physiographic Unit.
The study area covered the municipality of Ancona (Marche, Italy), affected by an intensive use of coastal area and an accentuated erosive dynamic.
The Ancona littoral has been divided in three Physiographic Units, coastline portions with homogeneus charactheristics:
• N.1 Promontory (Conero area)
• N.2 Port (Ancona Portual Area )
• N.3 Alluvial Plan
The Sensitivity Coastal Index (ISC) has been calculated using the alghoritm, for every Physiographic Unit:
ISC= SLR+TEV+HWL+GEC+ARice+ODC
The ISC Index represents the sum of points of pressure indicators.
Once defined the local area RICE buffer, the pressure indicators in relation with the current and expected future exposure to coastal erosion and flooding at local level are
- Sea level rise–SLR (best estimate next 100 years)
- Shoreline evolution–TEV (erosion or accretion)
- Highest water level–HWL (surge level)
- Geo morphological coastal type–GEC (susceptibility to erosion)
- Elevation of near shore coastal zone-ARICE
- Coastal defence works systems–ODC (engineered frontage including protection structure)
The Vulnerability Index (IVC) has been calculated using the algorithm
IVC = P Rice+ U Rice + E Rice +U10km
The IVC evaluate, for every Physiographic Unit, the potential impact of erosion and flooding through impact indicators, listed below:
- Population living within the RICE area (P RICE)
- % of coastal urbanisation and industrial areas in the RICE (U RICE).
- % of high ecological value areas in RICE
- (E RICE)
- % of urbanisation of coastal area in 10 Km (U10Km).
The results show how the Ancona urban area is characterized by an high/medium risk in the North sectors and how about 1093 hectares of territory are at risk of erosion and flooding in the next 100 years.
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