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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