Rug Um a Yo

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MAKERERE UNIVERSITY

COLLEGE OF ENGINEERING, DESIGN, ART AND TECHNOLOGY

SCHOOL OF ENGINEERING

DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING

WATER RESOURCES ENGINEERING 1

ASSIGNMENT 1

CASE STUDIES OF WATER PROJECTS IN AFRICA

KWESIGA DICKNESS KAKITAHI

REG No 09/U/496

14TH FEBUARY, 2012



HIGH ASWAN DAM (HAD)

The River Nile is the only main source for Egypt s water. Realizing that Egypt s territories lie in arid andsemi-arid zones, with very poor rainfall and underground aquifers and in the tail reach of the Nile, theEgyptians have given great attention, since ancient times, to their mighty river.

In the late 1940s, it was decided that the only feasible and practical solution for comprehensive controlof the Nile flow to safeguarding Egypt from devastating high floods and the perils of droughts and tosecure the water needed for sustainable irrigated agriculture was to build the High Aswan Dam as along-term storage reservoir and as a part of a multipurpose project.

The High Aswan Dam was constructed on the River Nile, 7 km south of Aswan in 1960. It is a rock filldam with grout curtain and clay core. Its total length is 3600 m and its height 111 m above the river bed.The storage capacity of its lake is 162 km 3. Its hydropower station capacity is 109 kWh per year. Water isdiverted into a channel at the middle of which there are 6 inlet tunnels which bifurcates and each of the12 branches deliver water to the hydraulic generating unit. The diversion channel is on the eastern Nilebank. The spillway is on the western bank. 12 175MW generators producing 2.1GW are installed on thedam. The maximum out flow is 11000m 3/s while an extra outflow of 5000m 3/s is realized through theemergency spillway.

Lake Nasser was created behind the Aswan High Dam. It is the largest artificial lake in the World (310miles in length) with a storage capacity of 132km 3. It is named after Gamal Abdul Nasser, the formerPresident of Egypt.

Purpose

The main aims of the construction of the High Aswan Dam can be summarized as follows:y protection of the Nile Valley and Delta from high floods and drought hazards that could persist

for several consecutive years;y generation of cheap and clean hydroelectric power;y provision of water for agriculture

Benefits

Water Security and Availability

The long-term or continuous storage policy and programme of the HAD lake (Nasser s lake) secured forEgypt an annual water quota of 55.5 km3 instead of a previous mean annual 48 km3, of which at least22 km3 were to be released tothe Mediterranean during the flood period (August- November).The construction of HAD and the 1959 agreement managed to satisfy both Egypt and Sudan s irrigationrequirements for land under cultivation and plans for future land expansion. Farmers were assured of having their water demands met at the right time. They managed to irrigate their crops periodically inaccordance with the schedule of plantation and growth till harvesting time, giving a very high yield of crop production in spite of poor yield of the catchment during those years.







CABORABASSA DAM Cabora Bassa is an arch dam and hydroelectric facility on the Zambezi River in western Mozambique.The dam, located about 80 miles (125 km) northwest of Tete. The Cahora Bassa Dam system is thelargest hydroelectric scheme in southern Africa with the powerhouse containing five 415 MW turbines.It is one of the three major dams on the Zambezi river system. The dam began to fill in December 1974after construction was commenced in 1969 by the Portuguese colonial government of Mozambique(Portugal) and is 171 m (560 ft) high by 303 m (994 ft) wide at the crest.

The dam impounds Lake Cahora Bassa, which is 150 miles (240 km) long and 19 miles (31 km) wide at itswidest point. The lake has a capacity of 51,075,000 acre-feet (63,000,000,000 cubic m) and extends tothe Zambia-Mozambique border.

The system includes two converter stations, one at Songo in Mozambique and the other at Apollo inSouth Africa. There are two parallel lines between these two stations, covering 1,400 km, of which 900km is in Mozambican territory. These HVDC lines work at 533 kV and in Mozambique territory only have

about 4,200 towers.

Facts about Cahora Bassa Dam12Length of the lake 270 kmArea 2660 km2Catchment Area 1200 000 km2Capacity 52,000 million cubic metresAverage inflow 2,800 cm3 per second (cumecs)Flood inflow Above 30,000 cumecsWall height 160 metresDam Crest Altitude 331 metresWall Type Double curved concrete arch

Unlike Kariba Dam, which is jointly owned by the governments of Zimbabwe and Zambia, Cahora BassaDam is 82 percent owned by the Portuguese government through its firm, Hidroelectrica de CahoraBassa (HCB), while the government of Mozambique has only 18 percent of shares in the dam. In terms of transmission of the power, ESKOM South Africa offers much of the technical expertise

The project is financed by Portuguese government budget appropriations and by credits from aconsortium of Portuguese banks and the South African Industrial Development Corpora-tion (IDC).Export finance credits were granted by the Banque de Paris et Pays Bas (Paris), Union Acceptances(Johannes-burg), Banca Comercial (Rome), and Deutsche Bank (Frank-furt/Main). The West Germangovernment-backed Hermes export insurance company granted guaranties totalling about US $133

million. It will be remembered that a lot of controversy surrounded the construction of this dam. Theimpact of African opposition to the Portuguese Zambezi Development Scheme and in particular to thecon-struction of the Cabora Bassa hydro-electric dam in Mozam-bique was first felt in Europe in 1968and reached its climax in 1971. It has influenced the thinking and the decisions of a great manyindividuals, groups, and organizations in the United States as well.



Purpose

The dam was purposely constructed to produce electricity at very economical rates in Mozambique andexport it to the neighboring countries like South Africa

Benefits

The dam operations came with the following benefits:

Development of infra-structure and the economic and social progress of the population in thatarea;

according to surveys, 3.7 million acres has become available as irrigated farmland (thiscompares favor-ably with the Aswan Dam project which provided Egypt with 1.5 million acres of additional farmland); suitably sized farms have been distributed among the local population andimmigrants;

Intensive exploitation of mineral resources with mining and whenever possible processing orpartial processing on the spot; presently known mineral wealth in the area consists of coal, iron,copper, fluorite and manganese deposits;

flood control; possible river shipping; fishing in the reservoir lake; electricity is also be sold to Malawi for the development of the Mlanje bauxite deposits. Power

is also exported to South Africa, Zambia and Zimbabwe.

Associated problems

Studies and research work done so far on the Cahora Bassa Dam indicate that the dam has causedconsiderable environmental impact on the river itself as well as to people living along the banks of theriver and the ecosystem in the river basin, especially on the flood based agriculture and fishingindustries.Disruption of the shrimp, prawn and fishing industryDue to loss of natural wetlands and disruption of silt sedimentation which form the basis for foodnutrients on which the shrimps and fish feed, the catching of shrimps, prawns and fish has gone downdrastically resulting in disruption to the industry.

Floods in 2000Even though some people have argued that the dams, especially the Cahora Bassa Dam, assisted incurbing the worst results of the 2000 disastrous floods in Mozambique, there is a lot of incriminatingevidence that the dams, including the Kariba Dam, aggravated the 2000 floods.

Little profit to the people of MozambiqueIn as far as development for the people of Mozambique is concerned; Cahora Bassa Dam plays a veryminimal role. Despite producing the cheapest electricity in the world, over 80 percent of the electricity isexported to South Africa and Zimbabwe, and only about 20 percent is utilized inMozambique. Yet, the ecological impacts are felt by the indigenous people in the country.



The civil war that halted the dam for17years, displacement of a large number of people should also bementioned

KAINJI DAM

Kainji Dam is a dam across the Niger River in western Nigeria. Construction of the dam began in 1964and was completed in 1968. The total cost was estimated at $209 million, with one-quarter of thisamount used to resettle people displaced by the construction of the dam and its reservoir, Kainji Lake.The dam is one of the longest dams in the world.

Kainji Dam extends for about 10 kilometers (6.2 mi), including its saddle dam, which closes off atributary valley. Most of the structure is made from earth, but the centre section, housing thehydroelectric turbines, was built from concrete. This section is 65 metres (213 ft) high. The dam is 215 ft(85.5m) in height from the toe to the crest and about 5 miles (8.04 km) in length. The lake is suppliedwith water from upper Niger and flows from Futa Djarlon Island through Guinea, Mali, Sierra Leone,Senegal and Niger. It stretches some 136 km upstream and has a breadth of 24 km at its widest point.Its maximum head elevation is 465 ft (141.73m) and maximum tail elevation is 330 ft (104m).

The dam was designed to have a generating capacity of 960 Megawatts; however, only 8 of its 12turbines have been installed, reducing the capacity to 760 Megawatts. The dam generates electricity forall the large cities in Nigeria. Some of the electricity is sold to the neighboring country of Niger. Inaddition, occasional droughts have made the Niger's water flow unpredictable, diminishing the dam'selectrical output. The dam has a single-lock chamber capable of lifting barges 49 meters (161 ft).

Kainji Lake measures about 135 kilometers (84 mi) long and about 30 kilometers (19 mi) at its widestpoint, and supplies a local fishing industry. In 1999, uncoordinated opening of floodgates led to localflooding of about 60 villages.

The Kainji dam has a main dam and a saddle dam. The main dam is constructed of concrete and therock fills. The saddle dam is rock filled and protects the main dam during flooding. There are fourspillways with hydraulic operated gates of 50 ft by 50 ft, which could be opened to control flood andalso to release water for use at the Jebba Dam downstream.

Hydrological information

Crest Maximum Elevation - 145.0m

Maximum Lake Elevation - 141.0m

Minimum Lake Elevation - 129.0m

Normal Maximum tail race Elevation - 129.0m

Maximum Crest Height to Foundation - 65.5m



Length of Dam - 5.50m

Spillway (Four Radial Gates) - 15m x 15.3m x each

Spillway Discharge Capacity - 7900m 3/sec

Intake gate 24 fixed wheel - 4.88m x 10.8

Hydraulic head - 24m 42.2m

Navigation - 13400m 3

Length of Improve River Channel - 6500m

Awuru lock maximum height - 7.7m

Total Storage - 15 x 10 3m3

Maximum Useable Storage - 12 x 10 3m3

Minimum Useable Storage - 3 x 10 3m3

Length of Kainji Reservoir - 136km

Maximum width of the widest portion - 24km

Purpose

Daily Trust investigations revealed that reason behind the establishment of the dam was to address thepower problem in the then Nigeria, which was basically characterized by diesel powered generators inparts of the country, while the larger part remained in darkness.

As the Nigerian population with electricity needs continued to grow with considerable amount of industries, the need to diversify into other sources of electricity became imperative, and the need tohave one with large capacity to generate huge amount of power became a very important factor.

Benefits

Kainji is the main stay of power generation in Nigeria. Since its machines are suitable for frequencyregulation to sustain power generation. Therefore, the station s importance cuts across every stratum of human endeavors, Political, Social, Economic, Tourism, Navigation, Fishing, Agriculture.

Social institutions like School, Hopsital, Homes, Offices, Communities, Towns, Cities have comeup with electricity availability

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 electricitygeneration.



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