Aqushela is a typical over-dimensioned

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

located in the Tanqwa-Abergele ''woreda'' of the

Tigray Region The Tigray Region, officially the Tigray National Regional State, is the northernmost regional state in Ethiopia. The Tigray Region is the homeland of the Tigrayan, Irob, and Kunama people. Its capital and largest city is Mekelle. Tigray is ...

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

. The

earthen dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and ...

that holds the reservoir was built in 1999 by the

Relief Society of Tigray The Relief Society of Tigray (abbreviated REST; ti, ማሕበራዊ ረዲኤት ትግራይ or ማረት, ''Maret'') is an NGO based in Tigray, northern Ethiopia. REST was founded in 1978 as an organisation providing relief efforts to civ ...

Dam characteristics

* Dam height: 11.5 metres * Dam crest length: 456 metres *

Spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

width: 16 metres

Capacity

* Original capacity: 810 000 m³ *

Dead storage Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...

: 121 500 m³ * Reservoir area: 20.5 ha These are the design values. In practice, the runoff from the catchment is largely insufficient to fill the reservoir, which serves only as shallow drinking pond for livestock.

Irrigation

* Designed irrigated area: 50 ha * Actual irrigated area in 2002: 0 ha

Environment

The

catchment A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the ...

of the reservoir is 13.5 km² large. The lithology of the catchment is

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

rock. Land use is strongly dependent on

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

: soils on metamorphic black limestone are used for cropping, while those on the schist and slate formations are under

savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient light to rea ...

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

. Lands on the green-reddish-gray metamorphic banded

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

formation are used for settlements. Most common soil types are: * in the metamorphic black limestone formation: Endoleptic

Calcisol A Calcisol in the World Reference Base for Soil Resources (WRB) is a soil with a substantial secondary accumulation of lime. Calcisols are common in calcareous parent materials and widespread in arid and semi-arid environments. Formerly Calcisols w ...

at the upper slope (plateau); Endoleptic

Cambisol A Cambisol in the World Reference Base for Soil Resources (WRB) is a soil in the beginning of soil formation. The horizon differentiation is weak. This is evident from weak, mostly brownish discolouration and/or structure formation in the soil pr ...

and

Vertic Vertic (Vertic A/S) is an independent global digital agency headquartered in New York, with offices in Copenhagen, Singapore, and Seattle. The agency creates digital marketing experiences based on technology, design and data. In 2022, Vertic was ...

Leptosol A Leptosol in the World Reference Base for Soil Resources (WRB) is a very shallow soil over hard rock or a deeper soil that is extremely gravelly and/or stony. Leptosols cover approximately 1.7 billion hectares of the Earth's surface. They are f ...

at the middle slope; Hypercalcic Calcisol at the footslopes and Grumic

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, alternat ...

at the lower slopes * in the schist and slate formations: Leptosol both at the upper slope and at the foot slope positions;

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. Internat ...

( Calcaric) over Hypercalcic Calcisol at the mid slope position and

Fluvisol A fluvisol in the World Reference Base for Soil Resources (WRB) is a genetically young soil in alluvial deposits . Apart from river sediments, they also occur in lacustrine and marine deposits. Fluvisols correlate with fluvents and fluvaquents o ...

at the valley bottom * in the green-reddish-gray metamorphosed banded marl: Leptic

at the upper slope, Haplic Calcisol at the foot slope, and

at the valley bottom

References

{{reflist Reservoirs in Ethiopia 1999 establishments in Ethiopia Tigray Region