INTRODUCTION
The essence of
this report is to document the experience acquired, observation, historical
background, disadvantages of constructing dams, advantage/economic importance
of kainji dam and recommendations on field trip to Kainji Dam which took place
on 22nd of November, 2013.
Kainji Dam is a
hydro-electric power station constructed to utilize the vast water body of the
River Niger whose construction started in 1964 and was completed in 1968. The total
cost was estimated at US$209 million, with one quarter of this amount used to
resettle people displaced by the construction of the dam and its reservoir.
LOCATION
Kainji Dam is located in Niger State
THE
HISTORY OF KAINJI POWER STATION
Power supply in Nigeria started in Lagos in 1896, when the men came to this part
of the world to exploit raw materials for their industry. As they move from the
coastal area of Lagos to the interior to exploit
cocoa in the West, Rubber and oil in the East and groundnut in the North, they installed
more generators in Kaduna, Ibadan,
Enugu and Kano.
These generators were maintained and controlled by Public Works Department (PWD).
With the growth of
industries and rapid urbanization; the demand for electricity rose faster than
supply. This prompted the Electricity Corporation of Nigeria (ECN) established
in 1950 to authorize the study of the HYDRO- ELECTRIC POTENTIALS of River Niger for large
and cheap supply of Electricity.
By 1962, Niger
Dams Authority (NDA) was instituted by an act of parliament “the proposed Hydro
Electric Station in Kainji”. The construction work was contracted to IMPREGILO
as major contractor. IMPREGILO is a consortium of three Italian companies: Impresit,
Giriola and Lodigiani.
Fund for the construction
of the dam was provided by the following governments and international organizations:
Federal Government of Nigeria, Government of Netherlands, International Bank
for Reconstruction and development Institute, U.K. Export credit Guarantee
Department.
Construction work
on Kainji Dam took off in 1964 with an inaugural ceremony performed by the then
Prime Minister of the Federation, Alhaji Abubakar Tafawa Balewa. In his speech,
he said. This is a practical Nigerian Project that will supply Electricity to
every region in the federation and create room for greater unity. The
construction lasted for four years. By 1968, it was ready for commissioning
with 4 sets of Kaplan turbines, Units 7, 8, 9 & 10 of 80MW each totaling 320MW.
The station was officially commissioned in February 1969 by Major General
Yakubu Gowon. In 1976, two additional sets of Kaplan turbine, Units 11 & 12
of 100MW each were installed, bringing the installed capacity of the station to
520MW. To further increase the installed capacity, two additional sets of fixed
blade or base load machines were installed, Units 5 & 6 of 120MW each,
making the total installed capacity of the station to be 760MW in 1978.
Units 1, 2, 3,
& 4 are open pits fervently awaiting the installations of additional four
machines to beef up power generation. The installation of these four machines
will complete the design of Kainji Power Station to effectively stabilize Power
Supply in Nigeria.
KAINJI LAKE (RESERVOIR)
The formation of
the Lake at the completion of the dam caused
the resettlement of 44,000 people of Borgu Emirate and Yauri Emirate. They were
resettled at New Bussa and Yelwa.
The Lake
has two flooding seasons, the white flood and the black flood. The white flood
is the accumulation of rainfall within the country that flows into the Lake.
While the Black flood
is the accumulation of rainfall from Gunea, Mali and Niger
that flows into the Lake. The White flood
arrives the lake in July since its journey to the Lake is not too far from the Lake. The Black flood arrives in December as it has to
travel long distance from Guinea,
Mali and Niger Republic
to the Lake. The length of the Lake is 136 Kilometres long. The Width is 24 Kilometres
at its widest point with maximum head elevation at 141. meters. While the maximum
tail elevations is 104 meters. The minimum head elevation at which the plant can
operate is 132 meters. The total storage capacity is 15billion cubic meters, 3 billion
constitute the dead storage, that is, water below the pen stock. The remaining
12billion constitute the life or usable storage. The hydrology department of
the station monitors the water from its source at Futa Jalion highland in Guinea for
water management. The department the
data inflow of water into the Lake and the outflows,
such as Turbine discharge, spill way discharge, evaporation and spillage.
THE
DAM
The dam is across
River Niger on kainji Island.
It was built to impound water to generate Electricity. It has the main dam and
the Saddle dam. The main dam consists of the concrete dam. The Saddle dam is a
safety device to ease the main dam in the event of (flooding. The Saddle dam us
rock filled. The dam has intake gates, each intake has a steel opening of 8.55 meters
in diameter. This is called the penstock.
It is where water from the Lake passes through
to rotate the turbine and convert mechanical energy to electrical energy. The
height of the dam from its toe to the crest is 65.5meters.
The length is 8.04
Kilometers. In compliance with the international law on dams across international
rivers, Kainji dam has two navigational locks the upper and lower locks. These
locks are opened for the navigation of barges of boats from the upstream to downstream
of the dam.
DAM
INSTRUMENTATION
The purpose of dam
instrumentation is to monitor the safe data behavior of the fill dam embankment
and the concrete structure operation and timely warming if the development of
any unusual condition overall structure stability of the different part of the
dam e.g. Main dam consist of the concrete gravity structure, The rock fill dam
right fill dam and left fill dam.
The equipment use for monitoring the safety of
the dam is as
follows:
RELIEF WELL: The purpose of
relief well is to reduce the seepage pressure in the soil foundation at the toe
of the dam.
STAND PIPEST: The purpose of the
stand pipe is to check the seepage pressure which could lead to piping or
jeopardize the stability of the saddle dam through the Foundation.
SEEPAGE MEASUREMENT: The seepage
observation to the detection and interpretation of changes in the rate and characteristics
of the flow, knowledge of the leakage
past of the dam.
EXTENTION GAUGET: Monitor
deflection of the dam embankment and settlement of the dam embankment.
TOTALIZING WEAR: To monitor the
total seepage water at the toe of the saddle dam.
THE PIEZOMETER: Hydraulic
piezometer are used to monitor the pore pressure the piezometer and embedded in
the core material of the rock fill dam. They are also installed in the foundation
and the embankments, and so also the electronic piezometer are used to monitor
water pressure in the dam foundation and embankment.
PLUMB LINE: The plumb lines
are installed in the concrete dam to measure the displacement of the part of
the structure relating to a fixed other foundation level. They are installed in
the spillway, intake block 1, intake block 6, intake block 10, service bays and
one inverted in intake block 1. The only one indirect plumb lines monitor the
movement of the dam foundation relating to the anchor is observed.
EXTENZOMETER: The purpose is
to monitor the swelling of the concrete structure due to attach aggregate
reaction in the concrete dam and across the spillway gate. The rod also monitor
the deflection and structure change in the concrete dam.
For convenient hydrological
operations, River Niger is
divided into Upper Niger, Middle Niger and Lower Niger.
Kainji Dam is located on the middle Niger. At this area, it is fed by
many tributaries such as R. Malando, R. Danzaki and R. Sokoto/Rima etc. Kainji
reservoir experiences two dual flood regime, i.e. Black and white flood. Back water
effect of the reservoir can be felt as far back as Kawara
Village after Yauri in Kebbi State.
Measurement of
rise and fall of Lake
Elevation on daily basis
in an hydrological priority. Monitoring of the tributary and main channel flows
by current mater method (discharge measurement) which facilitates the study of the
regime of each river flow into the basic and this enhances optimum power
generation.
Biannual
maintenance of automatic and manual staff gauges of the entire basin is another
important priority so as to acquire regular and accurate hydrological data.
ADVANTAGE
/ ECONOMIC IMPORTANCE OF KAINJI DAM
Kainji is the main
stay of power generation in Nigeria. Since its machines are suitable for frequency
regulation to sustain power generation. Therefore, the station importance cuts
across every stratum of human endeavors, Political, Social, Economic, Tourism, Navigation,
Fishing, Agriculture.
POLITICAL: The station
fosters unity, as it renders services to every part of the country and different tribes live together as staff of the
station.
SOCIAL: Social
institutions like School, Hospital, Homes, Offices, Communities, Towns, Cities
etc. Need Electricity to stay alive.
ECONOMIC: Electricity is
the mainstay of any economy. It is needed for industrial and commercial growth.
Also, the indices for measuring the growth of any economy is the quality if its
electricity
generation.
TOURISM: Visitor from
every part of the country and foreigners, especially students of various institutions,
visit the power station to acquaint themselves with the workings of an hydro-electric
station like Kainji.
NAVIGATION: Navigation has
been made easy with the construction of kainji dam. Apart from the rapids,
which on record caused the death of Mongo park, that have been removed, the flood
control by the dam management has been navigating less risk in the area of
Kainji dam.
FISHING:
The vastness of Kainji Lake,
allows for the catching of 7000 metric tons of fish annually. This provides the
needed protein for growth and body building.
AGRICULTURE:
With Kainji
Lake, farming through irrigation,
has been
made possible through out the year. In addition,
the Lake has increased the soil fertility of
villages.
DISADVANTAGE
OF THE DAM CONSTRUCTION
The construction
of large dams completely change the relationship of water and land, destroying
the existing ecosystem balance which, in many cases, has taken thousands of
years to create.
Throughout the
past few years, the negative impacts of dams have become so well known that
most countries have stopped building them altogether and are now forced to
invest their money into fixing the problems created by existing dams.
The following are
examples of some environmental problems caused by construction of dams.
Soil Erosion
One of the first
problems with dams is the erosion of land. Dams hold back the sediment load
normally found in a river flow, depriving the downstream of this. In order to
make up for the sediments, the downstream water erodes its channels and banks.
This lowering of the riverbed threatens vegetation and river wildlife.
Species Extinction
As fisheries
become an increasingly important source of food supply, more attention is being
paid to the harmful effects of dams on many fish and marine mammal populations.
The vast majority
of large dams do not include proper bypass systems for these animals,
interfering with their lifecycles and sometimes even forcing species to
extinction.
Spread of Disease
Dam reservoirs in
tropical areas, due to their slow-movement, are literally breeding grounds for
mosquitoes, snails, and flies, the vectors that carry malaria, schistosomiasis,
and river blindness.
Recommendation
and Conclusion
The importance of
kainji dam cannot be overemphasized as it stand tall in the generation of
electricity which is the key factor in the Nigeria economy however necessary
measures should be put in place to checkmate the adverse effects of
construction of dams on the natural environment and it habitat.
Conclusively this exercise is of enormous
advantages to students as it serves as an opener to how electricity is been
generated through hydro electric power station.
REFERENCES
Ambes
S. Douchet J.A (2003). Hydro Power Production Canadienne de’ Economique Vol.
36, No 3 587-607.
“An
inside look at kainji dam” Daily Trust Online. Retrieved July 21, 2012.
“An
inside look at kainji dam” Daily Trust Online. Retrieved July 18, 2012.
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