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Measurement of remaining storage, rate of siltation, and rate of erosion of the Ahmadu Bello University Farm Lake drainage Basin in Zaria
Baba, Adama; Akaegbobi, Mike & Schoeneich, Krzysztof
Abstract
Ahmadu Bello University Teaching Hospital at Shika, 547 beds and water demand 154 m3/d,
suffers from inadequate and irregular water supply. But there is a nearby abandoned impounding reservoir
constructed around 1966, with original storage capacity 636,300 m3. The authors propose to use this reservoir as the
main source of water for Shika Hospital. However, it is not known whether after 43 years of siltation, the reservoir
still contains enough water to meet water demand from the hospital. To determine, how much water is still available
in the impounding reservoir after many years of siltation, the authors embarked a boat and measured the remaining
storage of the reservoir as 349,911 m3. Thereafter calculated rate of siltation between years 1966 and 2009 as 6,600
m3/y, rate of erosion in the drainage basin during the same period as 0.559 mm/y, and safe yield during 176 days of
hydrological dry season as non existing, because after deduction of losses to evaporation calculated as 194,560 m3/y
and deduction of 272,700 m3 of environmental reserve - minimum necessary to preserve aquatic wildlife, there is no
active storage left. Since there is no active storage, there is also no safe yield and there is no water for Shika Hospital.
The authors conclude that the University Farm Lake cannot serve as source of water for Shika Hospital, unless it is
dredged to its original storage capacity. The impounding reserve will soon be lost. In some year to come there will be
little or no more water in it because it will completely be silted up as there will even be no trace of it seen on the
maps.
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