Coastal flooding
[1][5][6][7] Extraction of water from groundwater reservoirs in the coastal zone can instigate subsidence of the land, thus increasing the risk of flooding.
Natural defenses include physical features like gravel bars and sand dune systems, but also ecosystems such as salt marshes, seagrass and mangrove forests which have a buffering function.
Low atmospheric pressure is associated with storm systems and this tends to increase the surface sea level; this is a barometric setup.
These three processes interact to create waves that can overtop natural and engineered coastal protection structures thus penetrating seawater further inland than normal.
[19]: 5, 8 Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise, with another 42% resulting from thermal expansion of water.
These kinds of floods tend not to be a high risk to property or human safety, but further stress coastal infrastructure in low lying areas.
[27][9] Depending on the magnitude of the tsunami waves and floods, it could cause severe injuries which call for precautionary interventions that prevent overwhelming aftermaths.
[29] The coastal zone (the area both within 100 kilometres distance of the coast and 100 metres elevation of sea level) is home to a large and growing proportion of the global population.
[7] People's lives, homes, businesses, and city infrastructure like roads, railways, and industrial plants are all at risk of coastal flooding with massive potential social and economic costs.
[13][5][34][30] These places are characterized by their high biological diversity therefore coastal flooding can cause significant biodiversity loss and potentially species extinctions.
[5] "By 2050, “moderate” (typically damaging) flooding is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.
Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff.
However, it is best practice within landscape engineering to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water.
[39] Building regulations, coastal hazard zoning, urban development planning, spreading the risk through insurance, and enhancing public awareness are some ways of achieving this.
These include physical features like gravel bars and sand dune systems, but also ecosystems such as salt marshes, seagrass and mangrove forests have a buffering function.
[16] However, the catastrophic damage caused by the extensive flooding was the result of the highest recorded storm surges in North America.
[16] For several days prior to the landfall of Katrina, wave setup was generated by the persistent winds of the cyclonic rotation of the system.
This prolonged wave set up coupled with the very low central pressure level meant massive storm surges were generated.
