A sustainability index for anthropized and urbanized coasts: The case of Concon Bay, central Chile

The level of anthmpization in one of the most urbanized areas of central Chile (Concon Bay, 33 degrees S) is analyzed using a Coastal Sustainability Index (CSI). It is constructed from variables associated with driving forces (pressures) acting on geomorphological units with a known level of fragility (reference). The coastal conservation and intervention status was determined using analytical hierarchy process (AHP) and frequency ratio models combined with GIS. A correlation between driving forces and a high level of sustainability indicates a high degree of conservation of these geomorphological units, while a correlation between driving forces and a moderate or low level of sustainability indicates a high degree of intervention and little conservation of these natural units. It was established that 89.7% of the total area of ConcOn Bay presented low or moderate levels of sustainability, associated with residential and industrial uses and proximity to major roads. The high sustainability areas account for only 10.3% of the total area and consist of wetlands, beaches and dune fields that are under great pressure from real estate projects and various economic activities. Based on this index and the determination of areas with different sustainability levels, it is possible to orient decision making in land-use planning to control the driving forces in highly anthmpized, urbanized coastal zones in order to incorporate conservation measures for coastal ecosystems of high natural and cultural value.