Research axis 5 : dynamics & vulnerability of coastal zones
Coordinators: Serge SUANEZ (LETG/Geomer) and Mouncef SEDRATI (LDO/GMGL)
LDO – UMR 6538 (Laboratoire Domaines Océaniques), UBO, CNRS/INSU
LETG - UMR 6554 (Littoral Environnement Télédétection Géomatique), UBO - Nantes
AMURE (Ifremer - UBO)
Coastal hazards results from the combination of natural and complex social dynamics. The development of coherent and long-term strategies concerning coastal management issue is one of the major challenges facing the coastal development in the coming decades. In a context of global environmental change (sediment shortage and eustatic), variability of climate-ocean conditions and continental hydrology at various scales of time and space and extreme societal pressures of recent decades (growing residential attractiveness echoing the "coastal development" of human activities on a global scale, ever-increasing population pressures, artificial increase in land degradation and natural areas), vulnerability to various hazards (erosion, flooding, pollution, etc.) is an essential parameter to be included in the prospective for integrated coastal zone.
The axis 5 is following both scientific and operational objectives. On one hand, it concerns enhancing the understanding and comprehension of the induced risks on the coastal territories. This is achieved through taking into account the variability of both natural and anthropogenic forcing acting on different spatio-temporal scales. On the other hand, and based on this in-depth knowledge, it concerns bringing out elements to support public policy of the coastal risk management, such as erosion or coastal flooding, coastal environment pollution (hydrocarbons, heavy metals, etc.), taking into consideration the rapid effects of climate changes. In this context, society can, in fact, be seen as a variable “forcing” the coastal system, and, in a retroactive manner, as a component of the coastal system. To achieve this, the research realized in this axis needs to develop our knowledge of the extreme forcing damaging the coastal territories:
- The work is based on observing and measuring the physical and human mechanisms leading to critical situations in areas with high pressure. The complexity of the research’s subject imposes using, in synergy, different observation tools (field measurements, sociological investigations, economic evaluations, satellites images, airborne, naval, and terrestrial)
- As such, the vulnerability issue of the coastal territories is spatially and economically quantified though dynamic analyses of the ground use and occupation, and socio-economic issues.
- It also concerns identifying and analyzing coastal risks representations by different social groups present in these territories, and to study the modalities and the role of different actors in the governance and decision-making.
- Based on this knowledge, the final aim is to model these dynamics and their impacts. This will allow us predict different scenarios and reliable prospective that may be used in a managerial context.
However, whether such anthropogenic forcing related to increasing urbanization of coastal areas, or natural forcing related in particular to the rise of contemporary sea level estimated at 3 mm / year on average with local variations from which projections can be made, or the likely increase in weather-marine paroxysmal events whose return periods are still poorly identified, it becomes necessary to:
- Develop and enhance techniques of observing and surveying costal evolution
- Modeling the interaction between coastal evolution (under both natural and anthropogenic impact) and the coastal vulnerability
- Understand the implications of climate change and / or climatic conditions on the urban spaces in the coastal zone in order to anticipate and implement appropriate management policies, to reflect the societal implications of current environmental changes in terms of loss of life, damage property and socio-economic issues, possible compensation of victims and possible displacement of residents that will result;
- Preparing the future adaptation of coastal defenses, polder dikes and port infrastructure, which will in some cases be raised and strengthened to continue to play their role in relation to marine weather-for which they had not been provided;
- The provision of new anti-flood defenses, or fight against erosion, or strategies of decline.
Also, in this context, the priority is to strengthen knowledge on coastal hazards and risks and to support knowledge-based management decisions. This work is all the more necessary that scientific uncertainties still exist on many changing trends of natural forcing affecting the coastal zone and the acquisition of new knowledge on hazards remains an imperative. Our work plan should also reflect on the sharing of knowledge between scientists and with different social groups involved in coastal risk management.