Coastal vulnerability assessment with the use on natural and human induced indicators G. Alexandrakis 1 , S. Petrakis 1,2 , M. Vousdoukas 3 , G. Ghionis 1,2 , E.Hatziyanni 4 and N. Kampanis 1 . 1. Institute of Applied and Computational Mathematics, Foundation for Research and Technology, Hellas, Nikolaou Plastira 100, Vassilika Vouton,70013 Heraklion, Crete, Greece 2. Department of Geography & Climatology, Faculty of Geology & Geoenvironment, University of Athens, Panepistimioupolis, Zografou, 15784, Greece 3. Institute of Environment and Sustainability, Joint European Research Center, Via Enrico Fermi 2749, I-21027-Ispra, Italy. 4. Region of Crete, Directorate of Environment and Spatial Planning. M Mousourou 15, GR71201, Heraklion, Crete, Greece ABSTRACT Climate change has significant repercussions on the natural environment, triggering obvious changes in the natural processes that have a severe socio-economic impact on the coastal zone; where a great number of human activities are concentrated. So far, the estimation of coastal vulnerability was based primarily on the natural processes and less on socio-economic variables, which would assist in the identification of vulnerable areas. The present investigation proposes a methodology to examine the vulnerability of a highly touristic area in the Island of Crete to an expected sea level rise of up to ~40 cm by the year 2100, according to the A1B scenario of IPCC 2007. The methodology includes the combination of socio-economic indicators into a GIS-based coastal vulnerability index for wave-induced erosion. This approach includes three sub-indices that contribute equally to the overall index. The sub-indices refer to coastal forcing, socio-economic and coastal characteristics. All variables are ranked on a 1-5 scale with 5 indicating higher vulnerability. The socio-economic sub-index includes, as indicators, the population of the study area, cultural heritage sites, transport networks, land use and protection measures. The coastal forcing sub-index includes the frequency of extreme events, while the Coastal Vulnerability Index includes the geological variables (coastal geomorphology, historical coastline changes, and regional coastal slope) and the variables representing the marine processes (relative sea level rise, mean significant wave height, and tidal range). The main difficulty for the estimation of the index lies in assessing and ranking the socio-economic indicators. The whole approach was tested and validated through field and desktop studies, using as a case study the Elounda bay, Crete Isl., an area of high cultural and economic value, which combines monuments from ancient and medieval times, with a very high touristic development since the 1970s. VARIABLES CATEGORIES 1 2 3 4 5 Geomorphology GEO Rocky, Cliff coasts Medium cliffs, indented coasts Low cliffs, alluvial plains Cobble Beaches, Lagoon Barrier beaches, beaches, deltas Shoreline Erosion (%) ERO >2.0 from 1.0 to 2.0 from -1.0 to 1.0 from -2.0 to -1.0 <-2.0 Coastal Slope (%) CS 12 12 - 9 9 - 6 6 - 3 <3 Relative Sea-Level (mm/a) RSLR <1.8 1.8 - 2.5 2.5 - 3.0 3.0 - 3.4 > 3.4 Mean Wave Height (m) Hs <0.55 0.55 - 0.8 0.85 - 1.05 1.05 - 1.25 >1.25 Mean Tide Range (m) T >6.0 4.0 - 6.0 2.0 - 4.0 1.0 - 2.0 <1.0 Settlement SET Absent Village Small Town Large Town City Cultural Heritage SH Absent Local Regional National Global Transport TN Absent Secondary National road Ports Highway Land Use LU Bare rocks Grasslands Coastal areas Forest Agricultural Urban , Industrial Economic activities E Absent agricultural Commercial Industrial Tourism INDEX Very Low Low Moderate High Very High European Geosciences Union General Assembly 2014 Vienna | Austria | 27 April – 02 May 2014 0,52 85,55 0,28 7,81 5,84 0 57,21 37,46 5,09 0,22 0 20 40 60 80 100 Very low Low Medium High Very High Coastline % Vulnerability Ranking CVI SocCVI Study Area Elounda bay is located at the north-eastern part of Crete Island (Figure 1). It covers an area of about 10 km 2 . It is a closed with an entrance on the north side, which faces east. In the southern part of the area lies Sxisma, this is a Tombolo formation, which connects the island of Crete with Kolokitha Isl. The area is surrounded by various sites of archaeological interest, such as ancient cities and facilities (e.g. towers, reservoirs, churches, fortresses), dating from the Minoan era (27 th -15 th Cen. B.C.), where the -now underwater- city of Olus was present, and followed by posterior cities from Arab (8 th Cen. A.C.), Venetian (13 th -14th Cen. A.C.), and Othoman invaders (15 th -19 th Cen. A.C.). The most important historical monument is the Spinalonga fortress, located on a small island at the center of the gulf. It has recently been nominated to enter the UNESCO organization as a Natural Cultural Heritage. Method Firstly the Coastal Vulnerability Index of Gornitz et al (1993) was used which includes six physical variables is related in a quantifiable manner (EQ 1) Secondly, an alter Socioeconomic Vulnerability Index (SocCVI) was used based on the work of McLaughlin, et al (2002). This uses also social indicators such as the presence of settlements (SET), sites of cultural heritage (CH), transport network (TN), land use (LU) and economic activities (E) in the coast. In SocCVI, the variables are separated into three sub-indices: a coastal characteristics (CC) sub-index to determine the coast’s resistance to erosion (EQ 2), a coastal forcing (CF) sub-index to quantify the forcing variables (EQ3), and a socio- economic (SE) sub-index to identify the infrastructure potentially at risk (EQ4). Each one has equal input in the final index score and is estimated by equation 5. The variables and their rankings are shown in Table 1. ArcGIS (ESRI) was used to calculate the index and map the results. Variables were ranked on a 1-5 scale according to their perceived vulnerability (Table 1)  =ܫ  +  ܨ+ ܧ ͵ ሺͷሻ  =ܧ ܧ∙ ∙ܪ ∙  ∙ ܧ ͷ ሺͶሻ  =ܨ ∙ௌ∙ோ 3 (3)  =  ∙  ∙ ܪ ͵ ሺʹሻ  =ܫ ܧܩ ∙  ∙  ∙ ܧ ∙  ∙ ܪ ͸ ሺͳሻ Table 1: Variables and their rankings Results Conclusions "Vulnerability" is a human term introduced to serve management decisions and to prioritise the needs of actions. Regarding coastal areas, the indicators that are selected can strongly influence the final outcome and therefore management decisions. Thus, the socio-economic element of coastal vulnerability is a key issue in management practices. The addition of socio-economic variables in coastal vulnerability indices is extremely important. Although they present a challenge mainly estimating the indicators as most of them cannot be easily quantified. Therefore, the socioeconomic aspect is usually omitted from published indices, probably due to the difficulties in obtaining and ranking the data. The addition of socio-economic variables in an coastal vulnerability index can be a useful tool in making coastal management more focused to the actual needs of the society. CVI Small percentage very low vulnerability values. The Majority of the coastline is characterized with low vulnerability (85.55%). Mainly areas with rocky coasts, steep slopes, and man-made structures. Medium vulnerability areas present a very small percentage of 0.28 %. High and very high vulnerability areas correspond to the 7.81 % and 5.84 % respectively of the coastline. These areas are mainly beaches areas and soft rocky coast and are located, mainly, in the northern part of the bay (Figures 6 and 7). SocCVI No areas with very low vulnerability, while 57.21 % of the coastline is characterized with low vulnerability. They comprise mainly rocky coast areas. In the category of medium vulnerability the 37,46 of the coastline is ranked. In the categories of high and very high vulnerability the 5.09 % and 0.22 % is ranked respectively (Figures 5 and 6). Wind and waves ((figure 4)  The wider area is exposed primarily to Northern origin winds with frequency of occurrence of 32.96% Western and Southwestern origin winds have frequency 20.58% and 13.25% respectively.  Elounda bay is affected mainly by Northeastern and Eastern wind induced waves with frequency 7.37% and 3.44%. Storm conditions present a 1% annual frequency. Geomorphology (figure 2) Six coast types have been identified  Hard rocky coasts (HR) 58.89%  Soft rocky coasts at a rate of 2.34%  Beaches with length less than one kilometer (B2) (12.23 %)  Beaches with length less than 100m (B1) while 2.75 %  Beaches with length more than 1 km (B3) 0.39%  Man-made structures (HM) 23.41% Land use (figure 3)  Mainly agricultural with olive trees  High touristic with several tourist or leisure enterprises  Two main settlements, scattered houses and luxury hotels  Large percentage of the area is cover by grass land  No forests and no significant industries Transport networks (figure 3) In the area there is a coastal road, as part of the regional network and some dirt road that serve agricultural activities. The main road has major importance since it is the only one that which connects the coastal town of Elounda with the villages in the North. In the majority of its length it is supported by a coastal wall. Difference between indices CVI ranks the coastline more to extreme values either in low and high vulnerability, and mainly in Low vulnerability, due to the fact, that most of the coastline is characheristed by rocky coast and man-made structures. SocCVI ranks the coastline mainly in medium vulnerability values. This is due to the socioeconomic value that man-made structures and heritage sites, have in the index. In areas where there is no human activities the ranking is lower even if the area is more vulnerable in terms of environmental characteristics (eg. South area of the Elounda bay). Weight The ternary diagram shows the relative influence of each of the three sub- indices in the overall index score (figure 7). The overall index via its sub-indices shows that the coastline presents small difference between areas. The three sub indices have similar weight in the overall index. A general tendency for the coastal forcing and coastal characteristics sub-indices to dominate the overall score. In three areas, the socio-economic index has the least influence. Those are hard rocky areas with no human activities (Northern side of bay and Kolokitha Isl) Reference Gornitz, V. 1990. Vulnerability of the East Coast, USA to future sea level rise. Journal of Coastal Research, 1, (Special Issue No. 9), 201-237. McLaughlin, S., McKenna, J., Cooper, J.A.G. 2002, Socio-economic data in coastal vulnerability indices: constraints and opportunities Journal of Coastal Research, 1, (Special Issue No. 36), 487-497. Figure 2: Coast classification Figure 1: Location of the study area Figure 3: Land Use Figure 4: Wind frequencies and wave climate SocCVI CVI Figure 6: Vulnerability ranks for CVI (left) and SocCVI (right). wave climate Figure 7: Ternary diagram of the relative strengths of each of the 3 sub-indices Figure 5:Vulnerability ranks Kolokitha Isl Acknowledgments The authors were supported by a) the framework of the Action «Supporting Postdoctoral Researchers» of the Operational Program "Education and Lifelong Learning" (Action’s Beneficiary: General Secretariat for Research and Technology), and is co-financed by the European Social Fund (ESF) and the Greek State; b) IKYDA 2013: Estimation of the vulnerability of coastal areas to climatic change and sea level rise. Pilot study in the island of Crete. Funding Framework: Greek State Scholarships Foundation (IKY) and Deutscher Akademischer Austausch Dienst (DAAD); c) Effective management of erosion, protection and recasting of the coastline, of Plaka, Eastern Crete; Environmental effects of the coastal protection and restoration project. Funded by Region of Crete