Balancing lakeA balancing lake (also flood basin or Sustainable urban drainage scheme) is a term used in the U.K. describing a retention basin used to control flooding by temporarily storing flood waters. The term balancing pond is also used, though typically for smaller storage facilities for streams and brooks. In open countryside, heavy rainfall soaks into the ground and is released relatively slowly into watercourses (ditches, streams, rivers). In an urban area, the extent of hard surfaces (roofs, roads) means that the rainfall is dumped immediately into the drainage system.
RaftA raft is any flat structure for support or transportation over water. It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrels, or inflated air chambers (such as pontoons), and are typically not propelled by an engine. Rafts are an ancient mode of transport; naturally-occurring rafts such as entwined vegetation and pieces of wood have been used to traverse water since the dawn of humanity.
PondA pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond to be less than in area, less than in depth and with less than 30% with emergent vegetation helps in distinguishing the ecology of ponds from those of lakes and wetlands. Ponds can be created by a wide variety of natural processes (e.g.
StreamA stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks. The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater), daylighted subterranean water, and surfaced groundwater (spring water).
LakeA lake is a naturally occurring, relatively large body of water localized in a basin surrounded by dry land. A lake generally has a slower-moving flow than the inflow or outflow stream(s) that serve to feed or drain it. Lakes lie completely on land and are separate from the ocean, although, like the much larger oceans, they form part of the Earth's water cycle by serving as large standing pools of storage water. Most lakes are freshwater and account for almost all the world's surface freshwater, but some are salt lakes with salinities even higher than that of seawater.
Aquatic ecosystemAn aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic (slow moving water, including pools, ponds, and lakes); lotic (faster moving water, for example streams and rivers); and wetlands (areas where the soil is saturated or inundated for at least part of the time).
EphemeralityEphemerality (from the Greek word ἐφήμερος, meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, from digital media to types of streams. "There is no single definition of ephemerality". With respect to unique performances, for example, it has been noted that "[e]phemerality is a quality caused by the ebb and flow of the crowd's concentration on the performance and a reflection of the nostalgic character of specific performances".
Drainage divideA drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a single range of hills or mountains, known as a dividing range. On flat terrain, especially where the ground is marshy, the divide may be difficult to discern. A triple divide is a point, often a summit, where three drainage basins meet.
RapidsRapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Flow, gradient, constriction, and obstacles are four factors that are needed for a rapid to be created. Rapids are hydrological features between a run (a smoothly flowing part of a stream) and a cascade. Rapids are characterized by the river becoming shallower with some rocks exposed above the flow surface.
Fluvial processesIn geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes include the motion of sediment and erosion or deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed.
