Land reclamation makes otherwise inaccessible areas available for human use. Swamps, deserts, and submerged coastal lands are naturally inaccessible; surface mines, waste-disposal sites, and municipal landfills are waste areas created by human activity. The land reclaimed from such areas has been used for agricultural and forest crops, recreation, wildlife, and industrial or residential development.

RECLAMATION OF NATURALLY INACCESSIBLE AREAS

Naturally inaccessible areas are frequently the result of moisture extremes. Wet areas must be either drained or land-filled. Drainage (see drainage systems) is accomplished in several ways: by building a system of channels, by laying drainage pipes, and by pumping. In many cases embankments must be constructed to keep water out of the reclaimed areas. landfill operations require large quantities of suitable fill material such as sand, which is often obtained by dredging adjacent areas. Water is supplied to arid areas either by pumping it from underground sources or by transporting it through an irrigation system.

Reclamation of wetlands has significantly enhanced the well-being of several nations. The Netherlands is an outstanding example. Over a period of centuries the amount of arable land has been significantly increased by the construction of dikes, enclosing portions of the shallow coastal waters, which are then drained off. The Zuider Zee project, the first phase of which was a 29-km (18-mi) dike completed in 1932, has created nearly 200,000 ha (500,000 acres) of polders, which is land reclaimed from the sea. Because much of this land is below sea level, continuous pumping is required to maintain the desired water-table level.

Considerable areas in salt marshes have also been reclaimed in eastern England by constructing embankments that separate the marshes from the sea and draining the marshes both with ditches inside the embankments and through tidal sluices. Because the marshes are above sea level, pumping is not