Plattner, M. Tignor, S. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. Midgley eds. Geoscience Australia is committed to support Australia's capability to managing the impact of natural hazards, including coastal erosion. Geoscience Australia:. Coastal Erosion. Taken on June 20, , the photo on the right shows what often follows such undercutting: chunks of coastline tumbling into the sea. In the past, protecting the coast often meant "hardening" the shoreline with structures such as seawalls, groins, rip-rap, and levees.
As understanding of natural shoreline function improves, there is a growing acceptance that structural solutions may cause more problems than they solve. Additional reasons to avoid structural protective measures include the high costs to install and maintain them, state or local prohibitions against them, their propensity to cause erosion to adjacent beaches and dunes, and the unintended diversion of stormwater and waves onto other properties.
Many states have shifted toward non-structural shoreline stabilization techniques. Unlike structural projects, nature-based or "green infrastructure" protection measures enhance the natural ability of shorelines to absorb and dissipate storm energy without interfering with natural coastal processes.
One common strategy for dealing with coastal erosion is beach nourishment—placing additional sand on a beach to serve as a buffer against erosion or to enhance the recreational value of the beach. However, beach nourishment has also become a controversial shore protection measure, in part because it has the potential to adversely impact a variety of natural resources. Consequently, these projects must comply with a wide range of complex laws and regulations.
Beach nourishment is also expensive: check the Beach Nourishment Viewer to explore details about sand placement efforts for more than 2, beach nourishment projects since Adding sand to a beach does not guarantee that it will stay there. Some communities bring in huge volumes of sand repeatedly, only to see it wash out to sea in the next season's storms.
When completed in , the beach was 60 feet wide and sloped up to 5 feet above mean low water. As these are important feeding grounds for birds and other wildlife, it can have serious environmental consequences. Inter-tidal habitats are also important for local commercial fisheries, as they provide important nursery areas.
The EA seeks to replace them elsewhere through regional 'habitat creation programmes'. It is recognised that there will be a need to balance existing land uses in these areas with the requirement to replace protected habitats lost through coastal squeeze. More about shoreline management plans on the Environment Agency's website. Here the focus is on sea-level rise; other potential impacts are related to changes in meteorological conditions — wind, temperature and precipitation. Changes in the precipitation regime will affect the sediment discharge of rivers and the resulting sand supply to the coast.
Extreme conditions of strong precipitation and long periods of drought are expected to become more frequent. Temperature may play a role too, by its impact on soil erosion. The influence of variations of fluvial sand supply to the coast were shortly discussed in the previous section. Change in temperature will affect all life forms in the coastal zone. Coastal erosion is particularly sensitive to changes in coastal vegetation, dune vegetation for example.
Mangrove coasts are sensitive to temperature change, but also to sea-level rise, see Potential Impacts of Sea Level Rise on Mangroves. Change in the wind regime and wave climate will modify the alongshore and cross-shore sand distribution.
The alongshore sand distribution is very sensitive to the littoral drift, which strongly depends on wave direction. The shape of the cross-shore coastal profile is strongly influenced by wave run-up , with an important role for storm events with high waves and water levels. Great uncertainty still exists regarding predictions for local changes in wind regime and wave climate caused by climate change.
The sea level will rise globally as a consequence of global warming, but regional differences are considerable. This holds in particular for relative sea-level rise, i. Some coasts experience uplift especially in previously glaciated regions while others are subject to subsidence.
Uplift can always be considered "natural", whereas subsidence often has an important human-induced component groundwater, oil, gas extraction. According to the so-called " Bruun rule ", an increasing relative sea level will cause a shoreline setback, which is approximately equal to the sea level rise divided by the average slope of the active coastal profile, when considering equilibrium profiles.
Consider, for example, a sea level rise of 0. The setback caused by such a sea level rise will be 50 m. Littoral coasts consisting of fine sediments will be exposed to higher setbacks than coasts consisting of coarser sediments. Log in. Page Discussion. Read View source View history.
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