Aqushela is a typical over-dimensioned

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

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

Tigray Region The Tigray Region (or simply Tigray; officially the Tigray National Regional State) is the northernmost Regions of Ethiopia, regional state in Ethiopia. The Tigray Region is the homeland of the Tigrayan, Irob people, Irob and Kunama people. I ...

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

. 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 ...

that holds the reservoir was built in 1999 by the

Relief Society of Tigray The Relief Society of Tigray (abbreviated REST; or ማረት, ''Maret'') is an NGO based in Tigray Region, Tigray, northern Ethiopia. REST was founded in 1978 as an organisation providing relief (humanitarian), relief efforts to civilians. As ...

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 end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose sho ...

: 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 in which 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, th ...

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

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 t ...

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, causi ...

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) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), 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 sunli ...

. Lands on the green-reddish-gray metamorphic banded

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

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 ...

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 pro ...

and

Vertic VERTIC (Verification Research, Training and Information Centre) is a non-governmental organisation established in 1986 to promote effective verification of international agreements. VERTIC is primarily concerned with arms control and disarmament, p ...

Leptosol A Leptosol in the World Reference Base for Soil Resources (WRB) is a very shallow soil over continuous rock or a deeper soil that is extremely rich in coarse fragments (gravelly and/or stony). Leptosols cover approximately 1.7 billion hectares o ...

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

Vertisol A vertisol is a Soil Order in the USDA soil taxonomy and a Reference Soil Group in the World Reference Base for Soil Resources (WRB). It is also defined in many other soil classification systems. In the Australian Soil Classification it is c ...

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 Soil consolidation, unconsolidated materials. Regosols are extensive in erosion, eroding lands, in particular in arid and semi-arid areas and i ...

( 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 ...

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