Beach nourishment is the introduction of material along a shoreline to supplement the natural littoral drift.
There are several reasons for nourishing a shore. These include:
The effects of beach nourishment are generally short-lived (i.e., as long as the supply of material exists).
- Controlling erosive forces by providing a sacrificial area as a source of littoral material
- Supplementing littoral drift to offset particular actions or works
- Replenishing reserves of littoral material normally available in sand dunes
Beach fills are quantities of sand placed on the shoreline by mechanical means, such as dredging and pumping from offshore deposits or overland hauling and dumping by trucks. The resulting beach provides some protection to the area behind it and also serves as a valuable recreational resource.
The beach fill functions as an eroding buffer zone. As large waves strike it, sand is carried offshore and deposited in a bar. As the bar grows, it causes incoming waves to break farther offshore. The useful life of such a beach, which depends on how quickly it erodes, can be completely eliminated in a short period of time by a rapid succession of severe storms. The owner must expect, therefore, to periodically add more fill as erosion continues. Beach fills generally have a relatively low initial cost but a periodic maintenance cost of adding new fill (periodic nourishment).
The rate at which new fill must be added depends on the relative coarseness of the fill material in relation to the native beach material. Ideally, fill and native beach materials should be perfectly matched, but this is virtually impossible. Generally speaking, if fill material is coarser than the native material, the fill erodes more slowly and if it is finer, it erodes more quickly.
Beach nourishment and beach fills are often used in combination with construction of other protection methods such as a perched beach, or groin field.