Beach nourishment is the adding of sediment onto or directly adjacent to an eroding beach. This "soft structural" response allows sand to shift and move with waves and currents. A wide, nourished beach system absorbs wave energy, protects upland areas from flooding, and mitigates erosion. Beach nourishment also referred to as beach renourishment, beach replenishment, or sand replenishment.
Importance of Beach nourishment: Beach nourishment is the process of placing additional sediment on a beach or in the near shore. A wider and higher beach can provide storm protection for coastal structures, create new habitat, and enhance the beach for recreation.
A wider beach can reduce storm damage to coastal structures by dissipating energy across the surf zone, protecting upland structures and infrastructure from storm surges, tsunamis and unusually high tides. Beach nourishment is typically part of a larger integrated coastal zone management aimed at coastal defense. Nourishment is typically a repetitive process since it does not remove the physical forces that cause erosion but simply mitigates their effects.
History: The first nourishment project in the U.S. was constructed at Coney Island, New York in 1922–1923. Before the 1970s, nourishment involved directly placing sand on the beach and dunes. Since then more shoreface nourishments have been carried out, which rely on the forces of the wind, waves and tides to further distribute the sand along the shore and onto the beaches and dunes. The number and size of nourishment projects has increased significantly due to population growth and projected relative sea-level rise.
Consequences of Beach nourishment-
- The sudden input of massive amounts of sand can kill all the animals living on the beach.
- During nourishment, the beach becomes a major construction zone. The heavy machinery used to truck in and distribute new sand also kills beach animals and disturbs wildlife.
- The new sand may not be the same grain size or chemical makeup of the natural sand, changing the habitat that beach animals rely upon.
- The time needed for a beach ecosystem to recover from a single beach filling episode is not known, even when fill sand is the right size and type. Repeated or frequent episodes of nourishment can impede recovery of the beach community and ecosystem.
- Some types of animals, such as sand crabs, start their lives as free-floating larvae that drift through the ocean with the currents, so they can float in from elsewhere and recolonize the beach in a year. However, if the nourishment episode coincides with this event, then the population will not have a chance to begin repopulating the beach until the following year.
- Beach animals that carry their young in pouches (rather than producing free-floating young), such as amphipods and isopods, depend entirely on resident populations for recovery. These animals may require human help to return to a beach impacted by nourishment.
- The grain size of the introduced sand can influence how fast it erodes, leading to changes in beach shape.
- The added sand is often mined from places underwater or in riverbeds. Mining can alter those environments and make that limited resource unavailable for future projects.