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May Leiba
May Leiba is a reservoir located in the Dogu’a Tembien ''woreda'' of the Tigray Region in Ethiopia. It is named after the May Leiba River. The earthen dam that holds the reservoir was built in 1998 by the Relief Society of Tigray. Dam characteristics * Dam height: 18.9 metres * Dam crest length: 371 metres * Spillway width: 25 metres Capacity * Original capacity: 958 175 m³ * Dead storage: 191 635 m³ * Reservoir area: 16 ha In 2002, the life expectancy of the reservoir (the duration before it is filled with sediment) was estimated at 15 years. Irrigation * Designed irrigated area: 50 ha * Actual irrigated area in 2002: 5 ha A first problem is administrative: the dam is located in one ‘’tabia’’ and the command area in another ‘’tabia’’, leading to disagreements with regard to the sharing of the water. The larger part of the water that could be used for formal irrigation is lost through seepage across the limestone; the positive side-effect is that t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
May Leiba River
May is the fifth month of the year in the Julian and Gregorian calendars and is the third of seven months to have a length of 31 days. May is a month of spring in the Northern Hemisphere, and autumn in the Southern Hemisphere. Therefore, May in the Southern Hemisphere is the seasonal equivalent of November in the Northern Hemisphere and vice versa. Late May typically marks the start of the summer vacation season in the United States (Memorial Day) and Canada (Victoria Day) that ends on Labor Day, the first Monday of September. May (in Latin, ''Maius'') was named for the Greek goddess Maia, who was identified with the Roman era goddess of fertility, Bona Dea, whose festival was held in May. Conversely, the Roman poet Ovid provides a second etymology, in which he says that the month of May is named for the ''maiores,'' Latin for "elders," and that the following month (June) is named for the ''iuniores,'' or "young people" (''Fasti VI.88''). Eta Aquariids meteor shower appear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquitard
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude (or ''aquifuge''), which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could create a confined aquifer. The classification of aquifers is as follows: Saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; transboundary aquifer. Challenges for using groundwater include: overdrafting (extracting groundwater beyond the equilibrium yield of the aquifer), groundwater-related subsidence of land, groundwater bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltation
Siltation, is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or permanent) of fine sediments on bottoms where they are undesirable. Siltation is most often caused by soil erosion or sediment spill. It is sometimes referred to by the ambiguous term "sediment pollution", which can also refer to a chemical contamination of sediments accumulated on the bottom, or to pollutants bound to sediment particles. Although "siltation" is not perfectly stringent, since it also includes particle sizes other than silt, it is preferred for its lack of ambiguity. Causes The origin of the increased sediment transport into an area may be erosion on land or activities in the water. In rural areas, the erosion source is typically soil degradation by intensive or inadequate agricultural practices, leading to soil ero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regosol
A Regosol in the World Reference Base for Soil Resources (WRB) is very weakly developed mineral soil in unconsolidated materials. Regosols are extensive in eroding lands, in particular in arid and semi-arid areas and in mountain regions. Internationally, Regosols correlate with soil taxa that are marked by incipient soil formation such as Entisols in the USDA soil taxonomy or Rudosols and possibly some Tenosols in the Australian Soil Classification. The group of Regosols is a taxonomic rest group containing all soils that could not be accommodated in any of the other groups. Excluded from the Regosols are weakly developed soils that classify as Leptosols (very shallow soils), Arenosols (sandy soils) or Fluvisols (in recent alluvial deposits). These soils have AC- profiles. Profile development is minimal as a consequence of young age and/or slow soil formation. Land use and management of Regosols vary widely. Some Regosols are used for capital-intensive irrigated farming but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Catena
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem. Most s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertisol
A vertisol, or vertosol, is a soil type in which there is a high content of expansive clay minerals, many of them known as montmorillonite, that form deep cracks in drier seasons or years. In a phenomenon known as argillipedoturbation, alternate shrinking and swelling causes ''self-ploughing'', where the soil material consistently mixes itself, causing some vertisols to have an extremely deep A horizon and no B horizon. (A soil with no B horizon is called an ''A/C soil''). This heaving of the underlying material to the surface often creates a microrelief known as '' gilgai''. Vertisols typically form from highly basic rocks, such as basalt, in climates that are seasonally humid or subject to erratic droughts and floods, or that impeded drainage. Depending on the parent material and the climate, they can range from grey or red to the more familiar deep black (known as "black earths" in Australia, "black gumbo" in East Texas, "black cotton" soils in East Africa, and "vlei soils ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambisol
A Cambisol in the World Reference Base for Soil Resources (WRB) is a soil in the beginning of soil formation. The horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ... differentiation is weak. This is evident from weak, mostly brownish discolouration and/or structure formation in the soil profile. Cambisols are developed in medium and fine-textured materials derived from a wide range of rocks, mostly in alluvial, colluvial and aeolian deposits. Most of these soils make good agricultural land and are intensively used. Cambisols in temperate climates are among the most productive soils on earth. Cambisols cover an estimated 15 million square kilometres worldwide. They are well represented in temperate and boreal regions that were under the influence of glaciation du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Erosion
Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and animals (including humans). In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind (aeolean) erosion, zoogenic erosion and anthropogenic erosion such as tillage erosion. Soil erosion may be a slow process that continues relatively unnoticed, or it may occur at an alarming rate causing a serious loss of topsoil. The loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage networks. Soil erosion could also cause sinkholes. Human activities have increased by 10–50 times the rate at which erosion is occurring world-wide. Excessive (or accelerated) erosion causes both "on-site" and "off-site" problem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
