Coastal technologies or strategies for resilient or safer coasts
Introduction
Coastal engineering and defense is perhaps as old as civilization itself. Many revolutionary innovations in breakwater and harbor constructions such as underwater walls, solid breakwaters and low water-surface breakwaters date back to the Roman Empire. Ancient Romans were also the first ever recorded dredgers that understood and resolved silting problems. After the Roman empire collapsed, coastal development dwindled. Subsequent cultures, threatened by piracy and invasions, added few improvements on the basic Roman concepts. During the Renaissance, developing trade and industry revitalized the coastal exploitation. Until recent times, coastal protection and water management in coastal lowlands has been concerned to 'keep water out', 'defend property from water' and 'live on dry land' by means of solid structures like breakwaters, seawalls and revetments. Now, a global and especially European attitude change is occurring in response to the growing risk and uncertainty generated by climate change as well as new found expectations such as recreation and renewable energy generation. Since traditional coastal defenses have shown their environmental and socio-economical limitations, the focus of flood protection is being shifted to 'making space for water'. These techniques that allow some areas to be sacrificially flooded represent a return to the past. 'Hold the line' defenses on the other hand are moving from hard to soft defenses.
THESEUS and defense techniques
The THESEUS project, funded by the European Commission, aims to examine the application of innovative combined coastal mitigation and adaptation technologies that deliver healthy coastal habitats and a safe (or low-risk) coast for human use and economical development in the face of sea level rise and climate change. The primary objective is to provide an integrated methodology for planning sustainable defence strategies for the management of coastal erosion and flooding which addresses technical, social, economic and environmental aspects. Work Package 2 ensures the development of innovative hard and soft technologies for mitigation of flooding and coastal erosion hazard in the context of increasing storminess and sea level rise. Objectives include:
Improving existing defense structures and developing innovative new techniques
- by upgrading or elevating existing rubble mound breakwater armour and groynes.
- by stabilizing coastline through careful dredging, shore nourishment and reactivation of the littoral drift.
- by expanding upon low environmental impacting concepts like floating breakwaters
- by creating low environmental impacting barriers like artificial reefs of reefballs or geotextile sand containers.
- by improving the stability of dike inner slopes to create overtopping resistant dikes.
- by promoting the restoration or development of natural shore protecting barriers as mitigation method.
- by introducing/stimulating/maintaining shore protection vegetation.
- by reducing incident wave energy with innovative multipurpose solutions such as near-shore wave energy converters or artificial reefs aimed to improve spot surfability.
Natural habitats for coastal protection
- Spatial and temporal variability of salt marshes
- Biogenic reefs of Europe and temporal variability
- Dynamics, threats and management of dunes
- Dynamics, threats and management of salt marshes
- Dynamics, threats and management of biogenic reefs
A risk based approach, based on the climate scenarios developed within THESEUS Work Package 1 as well as literature review, is applied. The technologies were analysed considering a scenarios approach based on the short (2020), medium (2050) and long term (2080) climate conditions developed within WP 1. The technologies have been integrated in a holistic risk assessment model and multi-criteria decision making has been applied to select the sustainable defence strategy.
THESEUS major outcomes are synthesised in guidelines on coastal risk assessment and mitigation in a changing climate [1]. The best combination of mitigation options in study sites is being analysed through a GIS based decision support system whose application will be delivered through the project website.
References
- ↑ Zanuttigh, B., Nicholls, R., Vanderlinden, J-P., Thompson, R. and Burcharth, H. (editors) 2015. Coastal Risk Management in a Changing Climate. Elsevier, 670 pp.
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