SEDIMENT DELIVERY INTO THE KUBANNI RESERVOIR, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
SEDIMENT DELIVERY INTO THE KUBANNI RESERVOIR, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
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Date
2013-01
Authors
YUSUF, Yakubu Obadaki
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Abstract
In an attempt to assess the sediment delivery into the Kubanni reservoir, a continuous
monitoring of the four tributaries contributing sediments into the Kubanni reservoir,
Ahmadu Bello University, Zaria from 2011 to 2012 was carried out. The monitoring was
done by measuring their discharges using the 1200 and 900 v-notch weirs for the Malmo
and Tukurwa streams and the velocity-cross-sectional area method for Maigamo and
Goruba streams. Water samples were collected for onward analysis in the laboratory to
derive the suspended and dissolved sediment concentrations. Products of the sediment
concentrations and discharges gave the sediment loads and a rating relation between
sediment loads and discharges was used to determine the sediment yield of the
contributory tributaries. A February 2009 NIGERIASAT imagery was used for the
classification and characterization of the Land use/Land cover of each sub-basin by
supervised classification with maximum likelihood algorithm taking advantage of
spectral signatures using ILWIS 3.7 software.
The summary statistics including the channel suspended sediment yields of the four
tributaries is increasing progressively with the Malmo stream having the least (248.29
tons/yr) and the Goruba stream having the highest (12880.55 tons/yr). The situation is not
much dissimilar in the derived dissolved loads where the Malmo stream has the least
value of 89.99 tons/yr and the Goruba stream has the highest value of 8654.77 tons/yr.
The research revealed that the suspended sediment yield of the Malmo tributary has
reduced almost by half tribute to the efforts of the University administration in their
afforestation and reduction of farming activities within the sub-basin. There is a
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significant difference between the suspended sediment yields of the four tributaries.
There is also a significant difference between their respective dissolved sediment yields
and comparing the suspended and dissolved loads of each of the tributaries also revealed
a significant difference except for the Goruba stream. It was concluded that there exists
significant relationship between land use and sediment yields of the tributaries with the
scattered cultivation, apart from increasing progressively, making up the significant part
of the LULC subsets for each of the sub-basins.
The implication of this is that apart from the Malmo sub-basin, farming is prevalent, and
is therefore the major contributor to their sediment yields. This signifies the
overwhelming importance of LULC in determining sediment yield of rivers as inferred
by previous works. This conclusion is further corroborated with the anomaly observed in
the Maigamo sub-basin having the highest Specific Sediment Yield (SSY) as a result of
man’s influence farming very close to its gauging station thereby affecting the
consecutive increase in the SSY of the sub-basins.
Based on the findings, recommendations were made to the Ahmadu Bello University
administration among which are enforcement of the ban on farming, grazing and mining
strengthened with a legal backing, acquisition of more lands, encouraging annual tree
planting, building low check-dams, mounting sediment traps at strategic locations, long
term monitoring of the tributaries and dredging of the reservoir.
Description
A DISSERTATION SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
IN PARTIAL FULFILMENT FOR THE AWARD OF THE DEGREE OF
DOCTOR OF PHILOSOPHY IN GEOGRAPHY.
DEPARTMENT OF GEOGRAPHY
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
SEDIMENT, DELIVERY, KUBANNI, RESERVOIR, AHMADU, BELLO, UNIVERSITY, ZARIA, NIGERIA