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Antique Dutch windmills used to pump water into the embanked river to prevent waterlogging of the lowlands behind them. Waterlogging water is the saturation of soil with water. [1] Soil may be regarded as waterlogged when it is nearly saturated with water much of the time such that its air phase is restricted and anaerobic conditions prevail.
Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution. Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage.
Soil erosion (especially from agricultural activity) is considered to be the leading global cause of diffuse water pollution, due to the effects of the excess sediments flowing into the world's waterways. The sediments themselves act as pollutants, as well as being carriers for other pollutants, such as attached pesticide molecules or heavy metals.
It occurs when stress is applied to a soil that causes the soil particles to pack together more tightly, therefore reducing volume. When this occurs in a soil that is saturated with water, water will be squeezed out of the soil. The time required to squeeze the water out of a thick deposit of clayey soil layer might be years.
Canal linings are also used to prevent weed growth, which can spread throughout an irrigation system and reduce water flow. Lining a canal can also prevent waterlogging around low-lying areas of the canal. [1] By making a canal less permeable, the water velocity increases resulting in a greater overall discharge.
Due to precipitation, seasonal changes in Water content can lead to soil sloughing. [7] Soil sloughing is also an indicator of active soil movement and frequently requires action to reduce or prevent bank and slope failure. Soil water content is highly related to the mass erosion that leads to soil sloughing or even slopes failure. [7]
Cycles of wetting and drying cause soil particles to be abraded to a finer size, as does the physical rubbing of material as it is moved by wind, water, and gravity. Organisms may reduce parent material size and create crevices and pores through the mechanical action of plant roots and the digging activity of animals.
Dispersion is a process that occurs in soils that are particularly vulnerable to erosion by water. In soil layers where clays are saturated with sodium ions ("sodic soils"), soil can break down very easily into fine particles and wash away. This can lead to a variety of soil and water quality problems, including: