|Sand in Seaside Heights, New Jersey on 10/31/2012|
Photo by Mario Tama/Getty Images published here
While this is a particular and immediate case study, sand movement is an issue at many coastal cities. For example, project SANDAG is a $28 million regional sand replenshment project in the San Diego area; the Army Corps of Engineers proposes to spend $251 million on sand projects for Encinitas, Solana Beach, and San Clemente.
|Schematic of sand movement|
Beaches change all the time in response to the seasons and to individual storms. Change is the norm. During storms, waves attack parts of the beach system, moving sand from high-energy sites to lower energy environments. This process can take sand toward the shore, by the process known as "overwash" that appeared in the reports about Hurricane Sandy, or can take sand away from the shore, transporting it offshore and out, sometimes into sand bars. This process tends to cause storm waves to break further offshore and decreases the wave action that actually reaches the beach. As sea level rises in the future, beachs will migrate landward, somewhat like a tractor tread rolling over itself. The transport of sand into New York City or Seaside Heights (photo above) is an example of the transport of sand inward, and a portent of things to come if the number or intensity of hurricanes increase due to global warming.
Prior to human intervention, cycles of storms would work on beaches, repeating this process over and over on many scales, resulting in the beaches that we had in the early part of the 20th century. As we humans have constructed infrastructure, often far from the beaches, the supply of sand to the coasts has been greatly altered, often reduced. Thus, the normal beach building processes have, for many decades, been altered by humans. Beaches are now, at great expense, often only replenished as sand is carted from one place to another in an ongoing intervention with where "Mother Nature" wants to put it. Fittingly, the first beach replenishment project in the U.S. was at Coney Island in 1922-1923.
Here's a link to a before and after image of the Mantoloking Bridge and damage near it where the hurricane cut a new connection across the barrier island connecting the Atlantic Ocean and the Jones Tide Pond. This bridge, built in 2005, cost nearly $24 million, with an additional $5 million for design and purchase of rights-of-way. It has been labelled as "unstable" now.