What risks are coastal areas exposed to?
Coastal territories are exposed to risks that are exacerbated by global warming. Several types of risks exist: those linked to erosion, submersion, and flooding, as well as risks caused by heavy soil impermeabilization and rainwater runoff, all within the context of climate change. It is the combination of these risks that makes the coastline sensitive, requiring us to envision scenarios that combine them.
Certain territories are primarily dominated by erosion, others by submersion, while some areas experience a mix of both. Tropical zones must also contend with soil liquefaction dynamics and earthquakes. This distinction is crucial because the resulting damage differs: in the event of flooding, water destroys but eventually recedes, whereas erosion affects land permanently. Consequently, the proposed solutions vary accordingly.
To protect against submersions and flooding—episodic events, though increasingly frequent—buildings can be adapted by ensuring that living spaces are elevated sufficiently and that the layout of uses adapts over time. In the event of a flood, damage to lower floors impacts residents less severe. Constructing dikes and protective structures is another option, though it raises questions regarding management and long-term maintenance. Where such structures already exist, their continuity and heightening must be maintained to remain effective. In high-risk zones, authorities may also ban construction on certain plots.
Regarding erosion and shoreline retreat, solutions primarily fall within urban planning and land management strategies. Urban planning must account for the principle that the closer one gets to the shore, the lighter the demands on the land should be. Heavy infrastructure, such as hospitals and highways, must be located further back from the coastline. The longer a structure is meant to last, the further inland it must be positioned.
These two approaches are bound to merge. Risk management techniques for submersion and flooding will need to go deeper and align more closely with the urban realignment demanded by erosion risks.
Should we favor ephemeral architecture along coastal areas ?
From an architectural perspective, we must restore more natural dynamics and question the “disassemblability” of buildings by turning to off-site construction and assembly techniques that allow structures to be dismantled and adapted. Shoreline changes and climate change force us to reconsider the very nature of architecture—a core theme of my thesis research.
In the collective imagination, as well as in architectural tradition, buildings are seen as durable elements handed down to future generations. The retreat of the coastline compels us to rethink this concept and seek alternative references. Soundness lies at the heart of these reflections—both the structural integrity of the building and the stability of the ground itself.
In the late 20th century, construction often proceeded with little regard for soil dynamics, movements, or site-specific characteristics. Yet, reading Renaissance architectural treatises reveals a profound attention to soil properties, alongside precise rules and recommendations regarding what to build on specific terrains. We must reconnect with that philosophy: start from deep soil analysis to inform our construction, while infusing the principles of lightness and modesty—ensuring the primary value of this architecture lies in leaving minimal impact behind.
Does architecture have an awareness-raising function ?
Yes, absolutely, architecture carries immense pedagogical value. I think, for instance, of the military bunkers along the Atlantic and Normandy coasts—massive concrete structures that, as the shoreline retreats, collapse and fall into the sea. These remnants starkly illustrate what happens when we build too rigidly, failing to anticipate how the land will evolve.
Another notable example is La Rochelle, where flood protection measures blend seamlessly into heritage urban furniture. In doing so, the city stagingly reveals how water penetrates the urban fabric, signaling its presence through the adaptation of public spaces. During storm events, certain urban areas become inaccessible as water flows through them in a guided, controlled manner. This approach to redesigning spaces—relying on localized defense solutions such as embankments, small levees, and targeted waterproofing—heightens public awareness: residents continue to live in these territories, but with the clear understanding that water will return.
In Lacanau, the upcoming removal of parking lots that allowed cars to drive directly onto the dunes next to the beach serves a similar purpose. Deconstructing these parking areas in favor of more accessible, natural public spaces sends a strong signal to residents: a redesign that brings back the natural dune system and native regional vegetation.
And what about territorial planning?
One of the major issues facing these areas is intensive land development, which is the primary driver behind the explosion of risks. However, this also means that territorial planning is a key lever for adaptation. While much thought goes into technical solutions for building more sustainably, the major sticking point remains that the coastline is already heavily built up. This raises crucial questions about renewing the existing urban fabric and intervening in what is already there.
If we want to stay in these places, how do we adapt the existing built environment? We must make more room for water and soil movements, reduce structural vulnerability, and create transparency in the buildings, infrastructure, and roadways that currently block the flow of water. In a way, managing existing heritage must go hand in hand with planning the new.
There is also a broader reflection to be had and tough choices to be made: should we stay in a given location, continuing to inhabit and develop it, even when it is high-risk? Financial dynamics play a major role here—coastal real estate is highly sought after, and land values remain elevated despite the inherent dangers of building there. How these parcels are valued and handled, particularly by insurance companies, is a crucial factor: as long as insurers continue to underwrite these properties, investors and developers face little deterrence.
On the other hand, urban planning must serve the evolving shoreline. Resilience strategies need to reshape local regulations and zoning codes—such as local urban plans (Plans Locaux d’Urbanisme, or PLUs). This offers a way to frame climate risks not as a punitive constraint, but as a catalyst for innovation and a powerful driving engine for architecture and spatial design.