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Sulluh
Sulluh is a river of northern Ethiopia. Rising in the mountains of Mugulat (3298 metres above sea level), it flows southward to Giba River which empties finally in the Tekezé River. Future Lake Giba will occupy the plain where Sulluh, Genfel and Agula'i Rivers meet. Hydrography It is a confined river, locally meandering in its narrow alluvial plain, with a slope gradient of 11 metres per kilometre. With its tributaries, the river has cut a deep gorge. Hydrology Hydrological characteristics The runoff footprint or annual total runoff volume is 133 million m³. Peak discharges up to 338 m³ per second occur in the second part of the rainy season (month of August) when there are strong rains and the soils are saturated with water in many places. The percentage of total rainfall that directly leaves the catchment as storm runoff (also called runoff coefficient) is 13%. The total amount of sediment that is transported by this river amounts to 614,000 tonnes per year. Median ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giba River
Giba is a river of northern Ethiopia. It starts at the confluence of Genfel and Sulluh (which rises in the mountains of Mugulat) (3298 metres above sea level) and flows westward to the Tekezé River. Future Lake Giba will occupy the plain where Sulluh, Genfel and Agula'i Rivers meet, and hence be the future source of Giba River. Hydrography It is a confined river, locally meandering in its narrow alluvial plain, with a slope gradient of 7 metres per kilometre. With its tributaries, the river has cut a deep gorge. Tributaries Main tributaries, from downstream to upstream, are * Tanqwa ** Tsech'i River ** May Qoqah ** Arwadito ** Adawro River * May Selelo * Zikuli River * Gra Adiam River, also called Bitchoqo River * Zeyi River * Inda Sillasie River ** May Zegzeg *** May Harena *** May Sho'ate ** May Be'ati River * Addi Keshofo River * May Gabat * Inda Anbesa * Ruba Bich'i River * Hurura ** Afedena River *** May Ayni ** Shimbula * Ilala River * Qarano River * Agula'i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genfel
Genfel is a river of northern Ethiopia. Rising on the foot of the Atsbi horst at 2253 metres above sea level, it flows southwestward to Giba River which empties finally in the Tekezé River. Future Lake Giba will occupy the plain where Sulluh, Genfel and Agula'i Rivers meet. Hydrography It is a confined river, locally meandering in its narrow alluvial plain, with a slope gradient of 9 metres per kilometre. With its tributaries, the river has cut a deep gorge. Hydrology Hydrological characteristics The runoff footprint or annual total runoff volume is 76 million m³. Peak discharges up to 300 m³ per second occur in the second part of the rainy season (month of August) when there are strong rains and the soils are saturated with water in many places. The percentage of total rainfall that directly leaves the catchment as storm runoff (also called runoff coefficient) is 12%. The total amount of sediment that is transported by this river amounts to 274,000 tonnes per year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Giba
Lake Giba is a reservoir under construction at the border of the Inderta; Kilte Awula'ilo and Dogu’a Tembien ''woredas'' of the Tigray Region in Ethiopia. The earthen dam that holds the reservoir is under construction in 2020. It will collect the water from the catchments of Sulluh River (969 km²), Genfel River (733 km²) and Agula'i River (692 km²). Dam characteristics The dam is aimed to provide drinking water to Mekelle and to regulate the river flow. * Dam height: 80 metres * Dam crest length: 1000 metres Capacity * Original capacity: 350 million m³ * Reservoir area: 9 km³ Average annual sediment input to the reservoir by the main rivers was calculated as 3.8 million tonnes: * Sulluh: 862,410 t * Genfel: 364,301 t * Agula'i River: 2,618,528 t Flooding The dam will occupy the wide valley bottom at the river confluences, which is currently occupied by farmlands and bushlands. The reservoir will extend into the lower Genfel and Suluh gorge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agula'i River
Agula’i is a river of northern Ethiopia. Rising in the mountains of Atsbi Wenberta (2676 metres above sea level), it flows southwestward to Giba River which empties finally in the Tekezé River. Future Lake Giba will occupy the plain where Sulluh, Genfel and Agula’i Rivers meet. Hydrography It is a confined river, locally meandering in its narrow alluvial plain, with a slope gradient of 8 metres per kilometre. With its tributaries, the river has cut a deep gorge. Hydrology Hydrological characteristics The runoff footprint or annual total runoff volume is 115 million m³. Peak discharges up to 520 m³ per second occur in the second part of the rainy season (month of August) when there are strong rains and the soils are saturated with water in many places. The percentage of total rainfall that directly leaves the catchment as storm runoff (also called runoff coefficient) is 12%. As limestone is present in 47% of the catchment this runoff coefficient is less than that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Floods
A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice or snow flowing over ice sheets or snowfields. Flash floods may also occur after the collapse of a natural ice or debris dam, or a human structure such as a man-made dam, as occurred before the Johnstown Flood of 1889. Flash floods are distinguished from regular floods by having a timescale of fewer than six hours between rainfall and the onset of flooding. Flash floods are a significant hazard, causing more fatalities in the U.S. in an average year than lightning, tornadoes, or hurricanes. Flash floods can also deposit large quantities of sediments on floodplains and can be destructive of vegetation cover not adapted to frequent flood conditions. Causes Flash floods most often occur in dry areas that have recently received precipitation, but they may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment Transport
Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural systems where the particles are clastic rocks (sand, gravel, boulders, etc.), mud, or clay; the fluid is air, water, or ice; and the force of gravity acts to move the particles along the sloping surface on which they are resting. Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, and other bodies of water due to currents and tides. Transport is also caused by glaciers as they flow, and on terrestrial surfaces under the influence of wind. Sediment transport due only to gravity can occur on sloping surfaces in general, including hillslopes, scarps, cliffs, and the continental shelf—continental slope boundary. Sediment transport is important in the fields of sedimentary geology, geomorphology, civil engineering, h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment Yield
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water (fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments. Classification Sediment can be classified based on its grain size, grain shape, and comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baseflow
Baseflow (also called drought flow, groundwater recession flow, low flow, low-water flow, low-water discharge and sustained or fair-weather runoff) is the portion of the streamflow that is sustained between precipitation events, fed to streams by delayed pathways. It should not be confused with groundwater flow. Fair weather flow is also called base flow. Importance Baseflow is important for sustaining human centers of population and ecosystems. This is especially true for watersheds that do not rely on snowmelt. Different ecological processes will occur at different parts of the hydrograph. During the baseflow ascending limb, there is frequently more stream area and habitat available for water-dependent species, spawning salmon for example. During the recession limb which in California is from May to October, there is increasingly less stream area, indigenous species are more adept at surviving in low flow conditions than introduced species. Geology Baseflow is derived from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stormwater
Stormwater, also spelled storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed land surface in ponds and puddles, evaporate back into the atmosphere, or contribute to surface runoff. Most runoff is conveyed directly as surface water to nearby streams, rivers or other large water bodies (wetlands, lakes and oceans) without treatment. In natural landscapes, such as forests, soil absorbs much of the stormwater. Plants also reduce stormwater by improving infiltration, intercepting precipitation as it falls, and by taking up water through their roots. In developed environments, such as cities, unmanaged stormwater can create two major issues: one related to the volume and timing of runoff (flooding) and the other related to potential contaminants the water is carrying (water pollution). In addition to the pollutants carr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerial Reconnaissance In World War II
A transformational growth in aerial reconnaissance occurred in the years 1939–45, especially in Britain and then in the United States. It was an expansion determined mostly by trial and error, represented mostly by new tactics, new procedures, and new technology, though rarely by specialized aircraft types. The mission type branched out into many sub-types, including new electronic forms of reconnaissance. In sharp contrast with the case during the pre-war years, by 1945 air reconnaissance was widely recognized as a vital, indispensable component of air power. Pre-war situation In the interwar years, reconnaissance languished as a mission type and tended to be overshadowed by routine aerial mapping. This was despite the growth (in the United States and Britain) of a doctrine of strategic bombardment as the decisive weapon of war. Experience would soon prove that bombing was completely ineffective unless accompanied by intensive aerial reconnaissance. In the 1930s, gradual technic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
