Aqushela

Aqushela
Aqushela
	The reservoir never gets full with water, as evidenced by the trees growing on its bottom
	Aqushela
Coordinates	13°23′13″N38°49′48″E / 13.38695882°N 38.83006536°E Coordinates: 13°23′13″N38°49′48″E / 13.38695882°N 38.83006536°E
Type	Freshwater artificial lake
Basin countries	Ethiopia
Surface area	0.2 km2 (0.077 sq mi)
Water volume	0.81×106 m3 (660 acre⋅ft) (designed volume)
Settlements	Hidmo

Last updated September 27, 2019

Aqushela is a typical over-dimensioned reservoir located in the Tanqwa-Abergele woreda of the Tigray Region in Ethiopia. The earthen dam that holds the reservoir was built in 1999 by the Relief Society of Tigray.^[1]

A reservoir is, most commonly, an enlarged natural or artificial lake, pond or impoundment created using a dam or lock to store water.

The Tigray Region is the northernmost of the nine regions (kililat) of Ethiopia. Tigray is the homeland of the Tigrayan, Irob and Kunama peoples. Tigray is also known as Region 1 according to the federal constitution. Its capital and largest city is Mekelle. Tigray is the 6th largest by area, the 5th most populous, and the 5th most densely populated of the 9 Regional States.

Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a country in the northeastern part of Africa, known as the Horn of Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, the de facto state of Somaliland and Somalia to the east, Kenya to the south, South Sudan to the west and Sudan to the northwest. With over 102 million inhabitants, Ethiopia is the most populous landlocked country in the world and the second-most populous nation on the African continent with a total area of 1,100,000 square kilometres (420,000 sq mi). Its capital and largest city is Addis Ababa, which lies a few miles west of the East African Rift that splits the country into the Nubian and Somali tectonic plates.

Dam characteristics

Dam height: 11.5 metres
Dam crest length: 456 metres
Spillway width: 16 metres

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that the water does not overflow and damage or destroy the dam.

Capacity

Original capacity: 810 000 m³
Dead storage: 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.^[1]

Irrigation

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

Environment

The catchment of the reservoir is 13.5 km² large. The lithology of the catchment is Precambrian metamorphic rock.^[1] Land use is strongly dependent on lithology: soils on metamorphic black limestone are used for cropping, while those on the schist and slate formations are under savannah woodland. Lands on the green-reddish-gray metamorphic banded marl formation are used for settlements. Most common soil types are:^[2]

The Precambrian 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 Phanerozoic eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time.

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. Lithology may refer to either a detailed description of these characteristics, or a summary of the gross physical character of a rock. Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7.

A woodland or wood is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of primary or secondary succession. Higher density areas of trees with a largely closed canopy that provides extensive and nearly continuous shade are referred to as forests.

in the metamorphic black limestone formation: Endoleptic Calcisol at the upper slope (plateau); Endoleptic Cambisol and Vertic Leptosol at the middle slope; Hypercalcic Calcisol at the footslopes and Grumic Vertisol at the lower slopes
in the schist and slate formations: Leptosol both at the upper slope and at the foot slope positions; Regosol (Calcaric) over Hypercalcic Calcisol at the mid slope position and Fluvisol at the valley bottom
in the green-reddish-gray metamorphosed banded marl: Leptic Calcisol at the upper slope, Haplic Calcisol at the foot slope, and Fluvisol at the valley bottom

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 were internationally known as Desert soils and Takyrs.

Cambisol soil with a beginning of soil formation

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

Vertic is a Danish digital marketing and advertising agency founded in Copenhagen, Denmark in 2002. The company has offices in Copenhagen, New York City, Seattle and Singapore. Its clients include GE, Microsoft, Novo Nordisk, SAP, AARP and Vestas. Vertic is a development partner for LinkedIn and twice received The Internationalist's Award for Innovative Digital Marketing Solutions for its marketing of the LinkedIn platform.

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References

1 2 3 De Wit, Joke (2003). Stuwmeren in Tigray (Noord-Ethiopië): kenmerken, sedimentatie en sediment-bronnen. Unpub. M.Sc. thesis. Department of Geography, K.U.Leuven.
↑ Teka, Kassa; Nyssen, Jan; Teha, Nurhusen; Haile, Mitiku; Deckers, Jozef (1 August 2015). "Soil, land use and landform relationship in the Precambrian lowlands of northern Ethiopia". CATENA. 131: 84–91. doi:10.1016/j.catena.2015.03.010.

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[joke-1] 1 2 3 De Wit, Joke (2003). Stuwmeren in Tigray (Noord-Ethiopië): kenmerken, sedimentatie en sediment-bronnen. Unpub. M.Sc. thesis. Department of Geography, K.U.Leuven.

[2] Teka, Kassa; Nyssen, Jan; Teha, Nurhusen; Haile, Mitiku; Deckers, Jozef (1 August 2015). "Soil, land use and landform relationship in the Precambrian lowlands of northern Ethiopia". CATENA. 131: 84–91. doi:10.1016/j.catena.2015.03.010.