A plant which germinates, flowers, and seeds in a single season. A moisture condition associated with a seasonal reducing environment that is virtually free of dissolved oxygen because the soil is saturated by ground water or by water of the capillary fringe as in soils in Aquic suborders and Aquic subgroups. A subsurface layer of rock permeable by water. Although gravel, sand, sandstone and limestone are the best conveyers of water, the bulk of the earth's rock is composed of clay, shale and crystalline. An underground, water-bearing layer of earth, porous rock, sand, or gravel, through which water can seep or be held in natural storage.
Aquifers generally hold sufficient water to be used as a water supply.
Ar mor Artificial surfacing of bed, banks, shore, or embankment to resist erosion or scour. Armor Layer Erosion-resistant layer of relatively large particles on the surface of a streambed. Such layers typically result from removal of finer particles by erosion. The formation of an erosion-resistant layer of relatively large particles on the surface of the stream bed which resists degradation by water currents, resulting from removal of finer particles by erosion. The application of various materials to protect stream banks from erosion.