Run-off, composed of a mixture of water and soil along with any other organic or inorganic substances that may exist in the land, is the product of precipitation, snowmelt, over-irrigation, or other water coming in contact with the earth and carrying matter to streams, rivers, lakes, and other surface water bodies. Water (from the Old English word wæter; c. ... For the heavy metal band see Soil (band) Soil is a general term for the material that lies on the surface of the earth, supporting the growth of plants and serving as a habitat for animal life from microrganisms to small animals. ... Organic has several meanings and related topics. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... A fresh snowfall in Colorados (USA) high forests. ... Irrigation in the Heart of the Sahara Irrigation (in agriculture) is the replacement or supplementation of rainfall with water from another source in order to grow crops. ... Running Stream The primary meaning of stream is a body of water, confined within a bed and banks and having a detectable current. ... For the Second World War frigate class, see River class frigate The Murray River in Australia A river is a large natural waterway. ... A lake is a body of water surrounded by land. ... Surface water is water on the ground or in a stream, river, lake, sea or ocean; as opposed to groundwater. ...

In some cases it is spoken not about the runoff of the water, but of the carried substances, e.g., fertilizer runoff, when the latter ones are the major concern of the runoff.

The area within which runoff flows into a given body of water is a watershed, usually bounded by ridges of hills or mountains. This article explains the meaning of area as a physical quantity. ... A watershed or catchment basin is the region of land whose water drains into a specified body of water, such as a river, lake, sea, or ocean. ... The word Boundary has a variety of meanings. ... A ridge is a geological feature that features a continuous elevational crest for some distance. ... For the landform that extends above the surrounding terrain and that is smaller than a mountain, see the article on mountain. ... Mount Cook, a mountain in New Zealand A mountain is a landform that extends above the surrounding terrain in a limited area. ...

Excessive runoff causes flooding, typically locally during a thunderstorm, or more widely during an extended period of heavy rain. Rain causing melting snow also causes major runoff, especially in the springtime. Look up Flood in Wiktionary, the free dictionary A flood (in Old English flod, a word common to Teutonic languages; compare German Flut, Dutch vloed from the same root as is seen in flow, float) is an overflow of water, an expanse of water submerging land, a deluge. ... A roll cloud associated with a heavy or severe thunderstorm over Enschede, The Netherlands. ... Rain falling For other uses see Rain (disambiguation). ... Spring is one of the four seasons of temperate zones. ...

A common context of run-off deals with agriculture. When farmland is tilled and bare soil is revealed, rainwater carries billions of tons of topsoil into waterways each year, causing loss of valuable topsoil and clogging of valuable waterways.

Urbanization is another major culprit in causing excessive runoff, as impermeable surfaces such as pavement and buildings do not allow percolation of the water down through the soil to the water table. It is instead forced directly into streams, where erosion and siltation can be major problems, even when flooding is not. It may also lower the water table, making droughts worse, especially for farmers and other who depend on wells for groundwater. In geology, permeability is a measure of the ability of a material (typically, a rock) to transmit fluids through it. ... In mathematics, a surface is a two-dimensional manifold. ... This article is about the American English usage of pavement as the durable surfacing of roads and walkways. ... Building is either the act of creating an object assembled from more than one element, or the object itself; see also construction. ... In chemistry and other physical sciences, percolation is a type of filtering. ... For the heavy metal band see Soil (band) Soil is a general term for the material that lies on the surface of the earth, supporting the growth of plants and serving as a habitat for animal life from microrganisms to small animals. ... The water table is the upper limit of abundant groundwater. ... Look up Erosion in Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case... Silt refers to soil or rock particles of a certain very small size range (see grain size). ... A drought is an extended period where water availability falls below the statistical requirements for a region. ... Bales of hay on a farm near Ames, Iowa A farm is the basic unit in agriculture. ... For the pioneering virtual community, see The WELL. A well is commonly a pipe or tube installed in an artificial boring in the earth through which water, oil or gas can be obtained. ... Groundwater is water flowing within aquifers below the water table. ...