This assessment uses an archetype framework categorizing coastal C&S according to geomorphological characteristics, urban growth, economic resources and inequalities . Three broadly defined coastal settlement geomorphologies are used in each row: open coasts  and two transitional coastal zones with river mouths, distinguishing between estuaries  and deltas . Small island C&S are not singled out in this typology, because their coastlines often include the geomorphic features listed above, or require a different adaptation approach at larger spatial scales . Several coastal C&S have a combination of two typologies, for example, Maputo-Matola, Mozambique and Mumbai, India, having both open and transitional riverine coasts, and can be classed as mixed. We also acknowledge that several coastal C&S may have areas sited in mountainous topography that abruptly rises from the coast , but generally these cities have narrow, densely populated coastlines exhibiting these three archetypal categories . Arctic settlements are addressed separately in this cross-chapter paper.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report