Enriching the coast through its hinterland, and vice versa

It is the strip of land between the sea and the mainland, as opposed to the hinterland, which includes the drainage basin of a river—one that, by definition, flows into the sea or ocean! This definitive distinction between coastal area and hinterland runs counter to a reality: that of hydrology, which legitimately strives to treat water as a global mass connecting all waters within the same dynamic. Yet it reflects another reality: that of urban planning, which saturates the coastline while mistreating its back country. Approaching the development of this geographical whole as one system, through the lens of hydrology, makes it possible to address challenges that extend far beyond water itself—restoring more natural, and therefore more contemporary, qualities to both the city and its serving countryside.

It is frequent, if not systematic, for coastal cities to be settled where river meets sea. As they expanded, these cities paved over soils and more or less channeled — or even buried — their rivers.

The rift between the coastal fringe and its hinterland was thus complete. Consequently, during light rain, water no longer infiltrates the ground—drained away by sewers, failing to recharge aquifers. During heavy rainfall, water runs off, overflowing rivers overly constrained by levees, and floods the city — as evidenced by recurring disasters along the Mediterranean coast. Through its impact on the soil, urbanization has transformed rainwater from a “resource” into a “hazard.” It is up to us, as urban planners, to adapt our interventions to restore water’s lifesaving qualities.

By reconnecting the coastline with its hinterland—carved out and drained by the river—and by making cities porous through unpaving in favor of more nature, as well as by restoring streams and hedgerows in agricultural lands, rainwater revitalizes both surface and deep soils. It recharges and strengthens freshwater aquifers. This is the major challenge of our upcoming projects, as it secures the water resource during summer months while addressing broader global objectives. The first is to push back saltwater intrusions that insidiously mingle with depleted freshwater tables, seeping inland and rendering land unfit for agriculture. The second is to combat the subsidence of coastal cities caused by their increasing weight and the shrinkage of drying soils, which leaves them even more vulnerable to marine submersions.

Better integrating the hinterland with its coastline also restores the full significance of the waterway that flows through and animates both geometries. The river serves as a visibly strong continuity binding them together—a geographical, historical, and heritage continuum, as evidenced by the region’s shared place names. It naturally establishes itself as a backbone, extended by its tributaries to form the structural skeleton of a territory, uniting a diverse array of landscapes under a single logic: marshes, farmland, streams, bodies of water, roadways, suburban and inner-city urban areas, beaches, and maritime horizons.