A catchwater device is a large-scale man-made device for catching

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

from hills and the sky from precipitation by channeling it to reservoirs for commercial and domestic use later. Freshwater is a scarce natural resource due to pollution, droughts, and overpopulation. Catchwater is a sustainable mechanism to increase freshwater in areas facing droughts or polluted waterways.

Types

Catchwater drains

Catchwater drains may take the form of concrete

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface fl ...

s, such as in Hong Kong, where there are many. Alternatively, they may take the form of a large concrete sheet, smothering a hill, and preventing rainfall from entering the rock

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

, with a smaller channeling system for transport of the water to the

storage tank Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of heat or cold. The t ...

- this latter system is in operation in

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. In Hong Kong there are approximately 120 km of concrete channels, used as gutters built along hillsides in order to direct freshwater runoff into reservoirs for local water consumption. These catchwaters can overflow, causing dangerous hazards, erosive streams and blockages.

Earthship drains

An earthship drain is water that is collected from impervious surfaces that are channeled into cisterns. A

cistern A cistern (Middle English ', from Latin ', from ', "box", from Greek ', "basket") is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by t ...

is a well located underground. The water within these underground wells is heated by the sun. The water that is stored is used in domestic ways for washing dishes and bathing. Once water is used it is cycled and filtered in a module to be reused again

Rain barrels

Rainwater tanks, also known as rain barrels in North America, are used to collect runoff coming from precipitation to prevent contamination from entering waterways. The only use of water from rain barrels is used for commercial use such as gardening and agriculture. Rain barrels are large containers that are connected to buildings through a gutter system which catches runoff from roofs. Many households use rain barrels as a substitute for a to reduce the amount of water they waste for recreational activities.

Rain gardens

A Rain garden is a depression in the ground covered by vegetation that helps filter and restore freshwater back into the water cycle. Rain gardens are used to decrease the speed of water by capturing the water, so it does not become surface runoff through infiltrating the soil.

Advantages and disadvantages

Sustainability

Some drains are able to self-maintain through geomorphological equilibrium. Catchwater drains are predominantly used for agriculture. Agriculture uses the water to in catchwater drains for irrigation and the use for controlling flooding or other functions to direct large amounts of water away from crops during wet seasons. Catchwater drains also allow communities to wore down the water tables when they need to an allow the retentive of the water table to be restore after times of heavy use.

Environmental safety

Catchwater drains need a lot of landscaping and management. Rain gardens are not suitable for steep slopes unlike other types of catchwater drain Gardens can get congested and become impervious if land around the garden is not managed Due to the expense of these systems, they are generally only to be found where there is an extreme shortage of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

, because of geographical or political issues.

References

{{Reflist Water supply Stormwater management