A geomorphological analysis of the Comau Fjord was carried out to identify geohazards that are a product of current landform dynamics and processes. The geological setting of the area includes fractured metamorphic and volcanic rocks forming steep hillslopes in an active tectonic context due to the Liquiñe-Ofqui Fault Zone (LOFZ). Geomorphological and hazard mapping was performed using aerial photographs, GIS geoprocessing and fieldwork in January and May 2016 and February 2017. The susceptibility of landsliding was statistically assessed and validated with the inventory of landslides completed during fieldwork. The triggering of geohazards such as landslides and fluvial floods in the study area is associated with high annual precipitation (>5000 mm annually) with a concentration of rainfall that has increased in the last 50 years. Geohazard mapping demonstrated the potential for rock and earth falls, debris flows and river floods, as well as the potential impact of these geohazards on the area’s intensive aquaculture industry and a main national highway projected for the eastern flank of the fjord. In a geographical scenario of environmental and territorial change, the present and future human occupation of Comau Fjord’s coast constitutes potential hazard and risk conditions for aquaculture infrastructure and highway users.
Part of the book: Sea Level Rise and Coastal Infrastructure
The Chilean coast is controlled by the tectonics and structure, generating an irregular coastal landscape, with bays, marine terraces, sandy and gravel beaches, sand dune fields and Andean slopes, forming some mega cliffs that are attacked by waves. The Chilean coastline is shaped by headland bay beaches, with a dynamic coast modeled by south-western winds and south–north longshore current. We analyzed the case of the Coquimbo mega headland bay beach, which consists of four headland bay beaches. A methodological study was carried out on the morphometric parameters of the shoreline and the types of beaches dominated by waves along with geomorphological analysis of the coastal zone. We observed a mass transfer process from south to north. The northern sections of the bays are the places with the densest sand dune fields. This concentration of dunes occurs in each bay individually and in the mega bay as well. The sedimentary supply comes from Andean catchments to the shoreline and is transported and reworked by the longshore current to the northern area, where a huge sand field dune has developed, 120 km away from the mouth of Limarí River, the most southern catchment in the study area. In the mega bay, the current trend is a continuous sedimentary supply, despite the semi-arid conditions and the extreme drought that has affected the area since 2011. The study area is also a popular destination in Chile for beach tourism and is a place of interest for the mining industry.
Part of the book: Coastal Environments