A multi-scale coastal vulnerability index: A tool for coastal managers?

Erosion and tourism infrastructure in the coastal zone: problems, consequences and management.

Global models of tide, storm surge, and wave setup are used to obtain projections of episodic coastal flooding over the coming century. The models are extensively validated against tide gauge data and the impact of uncertainties and assumptions on projections estimated in detail. Global “hotspots” where there is projected to be a significant change in episodic flooding by the end of the century are identified and found to be mostly concentrated in north western Europe and Asia. Results show that for the case of, no coastal protection or adaptation, and a mean RCP8.5 scenario, there will be an increase of 48% of the world’s land area, 52% of the global population and 46% of global assets at risk of flooding by 2100. A total of 68% of the global coastal area flooded will be caused by tide and storm events with 32% due to projected regional sea level rise.

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Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

Geological control of beach morphodynamic state

Is barrier island morphology a function of tidal and wave regime

Mapping of coastal inundation hazard related to storms requires the combination of multiple sources of information regarding meteorological, morphological and dynamic characteristics of both the area at risk and the studied phenomena. Variables such as beach slope, storm wave height or wind speed have traditionally been used, but detailed geomorphological features of the area as well as long-term shoreline evolution trends must also be taken into account in order to achieve more realistic results. This work presents an evaluation of storm flooding hazard in Valdelagrana spit and marshes (SW Spain), considering two types of storm that are characteristic of the area: a modal storm with 1 year of recurrence interval (maximum wave height of 3.3 m), and an extreme storm with 6–10 years of recurrence interval (maximum wave height of 10.6 m), both approaching the coast perpendicularly. After calculating theoretical storm surge elevation, a digital terrain model was made by adjusting topographic data to field work and detailed geomorphological analysis. A model of flooding extent was subsequently developed for each storm type, and then corrected according to the rates of shoreline change in the last decades, which were assessed by means of aerial photographs taking the dune toe as shoreline indicator. Results show that long-term coastline trend represents an important factor in the prediction of flooding extent, since shoreline retreat causes the deterioration of natural coastal defences as dune ridges, thus increasing coastal exposure to high-energy waves. This way, it has been stated that the lack of sedimentary supply plays an important role in spatial variability of inundation extent in Valdelagrana spit. Finally, a hazard map is presented, where calculated coastal retreat rates are employed in order to predict the areas that could be affected by future inundation events.

Coastal flooding hazard related to storms and coastal evolution in Valdelagrana spit (Cadiz Bay Natural Park, SW Spain)

This work deals with the estimation of beach susceptibility to storminess in the Bay of Cadiz (SW Spain), and the concomitant environmental implications. For this purpose a comparison was made between the natural behaviour of beaches and the type and amount of coastal damage made by energetic waves in every beach type. Knowledge on the morphodynamic behaviour of beaches was obtained from a monthly topographic monitoring of 32 beach transepts normal to the coastline, performed during 30 consecutive months. Widely used morphodynamic parameters, like the Surf Similarity and the Surf Scaling parameters, were applied to the data, resulting in a general morphodynamic characterization of beaches, represented in a map of beach type distribution. Maximum coastal damage by storms was estimated by visual observations. Clear relationships between morphodynamic beach trends and amount of coastal damage have been obtained, and are presented in the form of a Beach Susceptibility Matrix. The matrix permits predictions of expected coastal damage associated with storms in other nearby beaches by means of a simple beach monitoring programme.

https://bioone.org/journals/journal-of-coastal-research/volume-36/issue-sp1/1551-5036-36.sp1.56/Utility-of-Morphodynamic-Characterisation-in-the-Prediction-of-Beach-Damage/10.2112/1551-5036-36.sp1.56.pdf

Utility of Morphodynamic Characterisation in the Prediction of Beach Damage by Storms

Variations in the disturbance depth were measured across four open mesotidal beaches on the Gulf of Cadiz coast of Spain during single tidal cycles, using rods and plugs of marked beach sands inserted in the foreshore. The studied beaches show a wide range of morphological variations and are distributed along a broadly homogeneous straight coast where energetic conditions remain more or less constant. Several parameters like wave height, beach gradient and grain size distribution have been compared with the variability of the recorded disturbance depth. As a conclusion, it is suggested that the morphodynamic regime is the characteristic that best explains the spatial variation of the disturbance depth, as well as the different response of the beaches under broadly similar energetic conditions. Three main morphodynamic classes have been observed in the studied beaches: reflective, barred dissipative and dissipative. In each case the morphodynamic situation controls the distribution and relative intensity of wave processes acting across the beach profile and, hence, the different rate of disturbance depth. The morphodynamic study of a beach permits an initial prediction of its morphological response under variable wave conditions.

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Depth of disturbance in mesotidal beaches during a single tidal cycle

The 100,000-km-long coastline of Europe has a long history of human occupationand intervention in coastal processes. Rapid coastal development that began inthe 1960s, however, has accelerated during the past decade with increased humanmobility and affl uence. This has had disastrous consequences for the European beachresource. Through a series of examples in the UK, Spain, and Italy, we show thatpoorly sited infrastructure is the primary reason for beach erosion problems, andthat decision-making in the area of beach management suffers inherent weaknesses;current practice concentrates on the symptoms (through coastal defense or nourishment)but has been unable to address the root cause (ill-planned development).Consequently, society has become locked into an open-ended series of ameliorativemeasures that, in turn, fuel ongoing development by removing the element of fi nancialrisk from coastal development. The scale of contemporary development on theEuropean coast means that the beach erosion problem will become more acute withtime, even without the anticipated large-scale coastal morphological adjustment tosea-level rise. Storms, tsunamis, and a reduction in sediment supply mean that existingcoastal infrastructure poses a long-term fi nancial liability. Eventually, the costsinvolved in continued defense may precipitate changes in public policy. There areindications of this happening, but in the meantime, development increases apace, notjust in Europe, but on adjacent Mediterranean and Black Sea coasts, to satisfy amainly European demand.

L. Del Río

Papers

Geological control of beach morphodynamic state

Coastal flooding hazard related to storms and coastal evolution in Valdelagrana spit (Cadiz Bay Natural Park, SW Spain)

Utility of Morphodynamic Characterisation in the Prediction of Beach Damage by Storms

Depth of disturbance in mesotidal beaches during a single tidal cycle

Bad beach management: European perspectives