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Sand Dam
Sand dams are a simple, low-cost and low-maintenance, replicable rainwater harvesting technology. They provide a clean, local water supply for domestic and farming use and are suited to semi-arid areas of the world. Operation A sand dam is a reinforced concrete wall (or a similarly robust and impermeable weir) built 1–5 metres high across a seasonal sand river. When it rains the dam captures soil laden water behind it – the sand in the water sinks to the bottom, whilst the silt remains suspended in the water. Research on Kenyan dams shows that only 1 to 3% of rainwater is retained behind any individual dam, the remainder continues its natural flow towards the ocean.Hut et al 2008 Eventually the dams fill with sand - sometimes after only one rainfall or over 1 – 3 seasons. 25 to 40% of the volume of the sand held is actually water. A mature sand dam can store millions of litres of water – refilling after each rainfall providing a year round supply of clean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dawa Eresa Subsurface And Sand Dam Project In Ethiopia , One Month in (Tibetan)
{{disambiguation, geo ...
Dawa or Dawah may refer to: *Dawa (Jurisdiction) (Arab. دعوى) *Dawa (Tibetan phrase), meaning "moon" or "month" *Dawa River, a river in Ethiopia *Dawah, proselytizing of Islam *''Al Dawa'', defunct political journal in Egypt *Dire Dawa, Ethiopia *Islamic Dawa Party, an Iraqi conservative political party *Dawa County (大洼县), Liaoning ;Towns (大洼镇) * Dawa, Jilin, in Ningjiang District, Songyuan * Dawa, Dawa County, Liaoning * Dawa, Changtu County, Liaoning *Dawa Chik Dawa or Dawah may refer to: * Dawa (Jurisdiction) (Arab. دعوى) *Dawa (Tibetan phrase), meaning "moon" or "month" * Dawa River, a river in Ethiopia *Dawah, proselytizing of Islam *'' Al Dawa'', defunct political journal in Egypt *Dire Dawa, Ethi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rainwater Harvesting
Rainwater harvesting (RWH) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or a reservoir with percolation, so that it seeps down and restores the ground water. Dew and fog can also be collected with nets or other tools. Rainwater harvesting differs from stormwater harvesting as the runoff is typically collected from roofs and other surfaces for storage and subsequent reuse. Its uses include watering gardens, livestock, irrigation, domestic use with proper treatment, and domestic heating. The harvested water can also be committed to longer-term storage or groundwater recharge. Rainwater harvesting is one of the simplest and oldest methods of self-supply of water for households, having been used in South Asia and other countries for many thousands of years. Installations can be designed for different scales including household ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weir
A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. Etymology There is no single definition as to what constitutes a weir and one English dictionary simply defines a weir as a small dam, likely originating from Middle English ''were'', Old English ''wer'', derivative of root of ''werian,'' meaning "to defend, dam". Function Commonly, weirs are used to prevent flooding, measure water discharge, and help render rivers more navigable by boat. In some locations, the terms dam and weir are synonymous, but normally there is a clear distinction made between the structures. Usually, a dam is designed specifically to impound water beh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa Sand Dams
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, Scramble for Africa, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wadis
Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley. In some instances, it may refer to a wet ( ephemeral) riverbed that contains water only when heavy rain occurs. Etymology The term ' is very widely found in Arabic toponyms. Some Spanish toponyms are derived from Andalusian Arabic where ' was used to mean a permanent river, for example: Guadalcanal from ''wādī al-qanāl'' ( ar, وَادِي الْقَنَال, "river of refreshment stalls"), Guadalajara from ''wādī al-ḥijārah'' ( ar, وَادِي الْحِجَارَة, "river of stones"), or Guadalquivir, from ''al-wādī al-kabīr'' ( ar, اَلْوَادِي الْكَبِير, "the great river"). General morphology and processes Wadis are located on gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of alluvial fans and extend to inland sabkhas or dry lakes. In basin an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slow Sand Filter
Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water. The length and breadth of the tanks are determined by the flow rate desired by the filters, which typically have a loading rate of per square metre per hour. Slow sand filters differ from all other filters used to treat drinking water in that they work by using a complex biological film that grows naturally on the surface of the sand. The sand itself does not perform any filtration function but simply acts as a substrate, unlike its counterparts for ultraviolet and pressurized treatments. Although they are often preferred technology in many developing countries because of their low energy requirements and robust performance, they are also used to treat water in some developed countries, such as the UK, where they are used to treat water supplied to London ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Dams
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand, for example, aragonite, which has mostly been created, over the past 500million years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Somewhat more rarely, sand may be composed of calciu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Security
Water security is the focused goal of water policy and water management. A society with a high level of water security makes the most of water's benefits for humans and ecosystems and limits the risk of destructive impacts associated with water. These include too much water (flood), too little water (drought and water scarcity) or poor quality ( polluted) water. A widely accepted definition of water security is: "Water security is the reliable availability of an acceptable quantity and quality of water for health, livelihoods and production, coupled with an acceptable level of water-related risks". Water security is framed as a situation where water-related risks are managed and water-related opportunities are captured but it is difficult to provide a set of indicators to quantify this. Policy-makers and water managers seek to achieve a variety of water security outcomes related to economic, environmental and social equity concerns. These outcomes can include increasing economic w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dams
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word ''dam'' can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities, such as Amsterdam and Rotterdam. History Ancient dams Early dam building took place in Mesopotamia and the Middle East. Da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desert Greening
Desert greening is the process of man-made reclamation of deserts for ecological reasons (biodiversity), farming and forestry, but also for reclamation of natural water systems and other ecological systems that support life. The term "desert greening" is intended to apply to both cold and hot arid and semi-arid deserts (see Köppen climate classification system). It does not apply to ice capped or permafrost regions. Desert greening has the potential to help solve global water, energy, and food crises. It pertains to roughly 32 million square kilometres of land. Methods *Managed intensive rotational grazing *Holistic management * Landscaping methods to reduce evaporation, erosion, consolidation of topsoil, sandstorms, temperature and more *Permaculture in general – harvesting runoff rainwater to grow plant communities polyculture, composting or multitrophic agriculture *Planting trees (pioneer species) and salt-loving plants (halophytes), such as Salicornia *Regeneration of sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Conservation
Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many countries have already implemented policies aimed at water conservation, with much success. The key activities to conserve water are as follows: any beneficial reduction in water loss, use and waste of resources, avoiding any damage to water quality; and improving water management practices that reduce the use or enhance the beneficial use of water. Technology solutions exist for households, commercial and agricultural applications. Water conservation programs involved in social solutions are typically initiated at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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