Dams in Developing Nations

Introduction Definition: structure built across a stream, river, or estuary to retain water (or debris)

Introduction History –Dams have been around for ~5,000 years Domestic and agricultural usage –Advances in technology coincides with population increase

Introduction "A history of dams - The useful pyramids“ Published by AA.Balkema Nicholas J. Schnnitter - Switzerland/Suisse (

Introduction

Introduction History –19 th & 20 th Centuries Increased electricity demand = larger dams Increased population = need for flood protection Dams now serve various purposes

Introduction Current uses of Dams –Hydroelectric power –Flood control –Water Storage –Tailings / Mining Dams

Types of Dams Arch DamsButtress Dams Gravity DamsEmbankment Dams

Types of Dams Arch Dams –Curved - dependent upon arch action for its strength. –Thinner and therefore require less material –Good for sites that are narrow and have strong abutments.

Types of Dams Arch Dams Source: Cracking Dams (

Types of Dams Buttress Dams –Face (front) is held up by a series of supports. –Have many forms - the face may be flat or curved.

Types of Dams Buttress Dams Source: Cracking Dams (

Types of Dams Gravity Dams –Resist the horizontal thrust of the water entirely by their own weight. –Typically used to block streams through narrow gorges. –Use a large amounts of concrete. This can be expensive. –Many prefer its solid strength to arch or buttress dams.

Types of Dams Gravity Dams Source: Cracking Dams (

Types of Dams Embankment Dams –Massive dams made of earth or rock. –Rely on their weight to resist the flow of water

Types of Dams Embankment Dams Source: Cracking Dams (

Types of Dams Tailings Dams –Tailings are waste material from the mining industry Must separate ore from rock “Floatation” method often used Waste is stored in tailings dams Source:

Types of Dams Tailings Dams –Three types of embankments downstream, upstream and centerline structures –Type used is dependant upon many factors, including Volume Seismicity, Etc. Source:

Upstream Design Tailings Dam Common Inexpensive Prone to failures Source:

Centerline Design Tailings Dam Mix of up and downstream design Cannot be used for water retention Source:

Downstream Design Tailings Dam Can hold more water More stable design Costs increase exponentially with height Source:

Types of Dams Other parts of a dam may include –spillways, gates, or valves –an intake structure conducting water to a power station or to pipelines –provision for evacuating silt carried into the reservoir –means for permitting ships or fish to pass the dam.

Forces that Act on a Dam Main forces –force of the reservoir water (W) –weight of concrete (C) –both forces together ArchButtressGravity

Forces that Act on a Dam Main forces –The main force on an embankment dam is water (W). –The weight of the dam is also a force,

Forces that Act on a Dam Other forces –internal water pressure –temperature variations in the concrete –earthquake loads –settlement of the foundation or abutments

Case Studies Brazil - Tucuruí Dam

Climate: –mostly tropical, but temperate in south Terrain: –mostly flat to rolling lowlands in north; some plains, hills, mountains, and narrow coastal belt

Brazil - Tucuruí Dam Background –93% of Brazils’ energy comes from hydroelectric –More than one million people have been displaced by the construction of Brazil’s dams –34,000 km 2 have been inundated by reservoirs –Little effort has been made for alternative energy

Brazil - Tucuruí Dam Background – The Tucuruí Dam –Part of a World Commission on Dams study on the subject of the development effectiveness of large dams. –Phase I – 1975 to 1984 –Phase II – began in 1988; first turbine scheduled to be operational by December 2002

Brazil - Tucuruí Dam Background – The Tucuruí Dam –Structural Type: Gravity dam Reservoir: 2,875 km 2 Length: 1,321 m Height: 77 m –Function / usage: Hydroelectric dam Power: 8,000 mW

Brazil - Tucuruí Dam Environment - current issues: –deforestation in Amazon Basin destroys the habitat and endangers a multitude of plant and animal species indigenous to the area –lucrative illegal wildlife trade –land degradation and water pollution caused by improper mining activities –wetland degradation

Brazil - Tucuruí Dam The Tocantins River –located completely within the province of Eastern Amazonia –Flows into the Amazon river estuary –Annual volume of 334km 3 –Catchment area of 758,000 km 2 (7.5% of the land mass of Brazil) –Contributes to a well-defined and stable climatic regime across this region

Brazil - Tucuruí Dam Socio-Economic Impact –Severity of the impacts was far greater than initially foreseen Population doubled in 10 years Mandatory relocation programs and economic migrations Massive layoffs after Phase I completion Compensation packages did not take into account cultural and historical values

Brazil - Tucuruí Dam Socio-Economic Impact –Parakanã Group split up and relocated numerous times August 1986, threatened to block the Transamazon Highway and employ terror tactics Parakanã Programme / Parakanã Indigenous Reserve. –Assimilate the group into mainstream culture –Establishment of villages and maintaining their traditional hunting and gathering activities

Brazil - Tucuruí Dam Socio-Economic Impact –Asurini Territory below the dam Affected by migrant workers and displaced people 1970’s – road built through 9 km of Asurini land 1997 – new power line contemplated Asurini resorted to the destruction of public infrastructure Road built, no power line, and no Asurini compensation

Brazil - Tucuruí Dam Socio-Economic Impact –Increase in: Malaria, schistosomiasis, etc, Industrial accidents, Alcoholism Sexually transmitted diseases and AIDS –Infant mortality in the 1980’s rates 6x that of Pará State and 5x that of all of Brazil

Brazil - Tucuruí Dam Effects on Ecosystems –Initially, concern was towards the effect of the ecosystems on the construction project –Water Quality Low dissolved oxygen levels downstream Reduced flooding downstream = fertilization processes Increase in mosquitoes = increase in malaria

Brazil - Tucuruí Dam Effects on Ecosystems –Fisheries Initially anticipated a high mortality rate during & after dam construction Actual rates much higher due to low D.O. & nutrient levels

Brazil - Tucuruí Dam Effects on Ecosystems –Terrestrial Impacts Submersion of 2,850 km 2 of land including large areas of rainforest Wildlife reserves with permanent a wildlife study group established (Operação Curupira) Bans on hunting and poaching Capture and release of some 280,000 animals. Total cost = US $30 million

Case Studies Three Gorges Dam - China

Background –Location: Sandouping, Yichang, Hubei province –Structural Type: Gravity Height: 181 m Length: 2,150 meters Reservoir Capacity: 1.39 trillion cubic feet –Function / usage: Hydroelectric dam 18.2 million kilowatts

Three Gorges Dam - China

Comparison between the Three Gorges Dam and the world’s largest dams (reservoir capacity, in cubic feet)

This image of Three Gorges Dam was collected by QuickBird on July 13, Three Gorges Dam is located in Sandouping, Yichang, in the Hubei Province of China. The completion date for the construction of the 181-meter tall dam is scheduled for 2009, when all 26 generators will be able to generate power. sample_imagery.shtml

Yangtze River, China Background –Construction phase: 1994 – 2009 –Functions: Flood control, power generation, improved navigation

Yangtze River, China Background –About 20,000 people are working nearly round the clock to complete the structure by –The lake that will form behind Three Gorges Dam will stretch for about 350 miles -- the distance from San Francisco to Los Angeles. –Three Gorges Dam reservoir will actually be visible from the moon! –Source:

Yangtze River, China Socio-Economic Impact –600,000+ people have had to be resettled –13 cities, 140 towns, more than 1,600 villages, and 300 factories will be submerged –Est. 1.3 – 1.9 million will eventually have to leave –Supposedly there are no contractual agreements with the resettlement authorities –Loss of culture, way of life, etc.

Yangtze River, China Archeological Impact –1,300 known cultural heritage sites affected –Budget for excavations severely reduced –Looting common One of China's premier Buddhist cave sites, Dazu has repeatedly been the target of thieves. (New China Pictures/Eastfoto)

Yangtze River, China Problems –Over budget –Coercion and violence have been used against communities affected by dams –Critics arrested or forced into exile –No Dam Inundation plan –Increased silt build-up –Decreased nutrient levels downstream

Case Studies San Marcelino Dam - Philippines

Climate: tropical marine –northeast monsoon (November to April); –southwest monsoon (May to October) Terrain: –mostly mountains with narrow to extensive coastal lowlands

San Marcelino Dam - Philippines Natural hazards: –usually affected by 15 and struck by five to six cyclonic storms per year; –landslides; –active volcanoes; –destructive earthquakes; –tsunamis

San Marcelino Dam - Philippines Natural resources: –timber, petroleum, nickel, cobalt, silver, gold, salt, copper The San Marcelino tailings dam spill –Dizon Copper-Silver Mines, Incorporated (DCSMI) –Operations ceased in 1997

San Marcelino

San Marcelino Dam - Philippines Two mine tailings dams –Bayarong Size: 122-hectare 47 million cubic meters of mine tailings Supposed to be able to withstand a 9.5 EQ –Camalca – silt & debris Catch Basin –Mapanuepe Lake

San Marcelino Dam - Philippines History –1991 Mt. Pinatubo erupted, creates Lake Mapanuepe (spillway weakened) –1998 spillway damaged by the effects of a typhoon

San Marcelino Dam - Philippines History –1999 Mines and Geosciences Bureau noticed “some seepages at and partial erosion of the tailings dam’s spillway” Recommended the following: –installation of siphons and electrical pumps –strengthening/preserving the remaining concrete portion of the spillway approach –opening of the previously constructed drain tunnel

San Marcelino Dam - Philippines History –1999 Recommendations heeded 10 days of rain from Typhoons Chedeng and Dodong proved recommendations not enough. New, more aggressive measures proposed

San Marcelino Dam - Philippines History –2002 August 27 – inspection reveals damage to dams & spillways, leakage into Lake Mapanuepe September 5 – the Department of Environment and Natural Resources called the sudden burst of the dams "unlikely" September 11 – spillway collapses, flooding low- lying villages with mine wastes and other chemicals September 12 – 1000 people evacuated

San Marcelino Dam - Philippines History –2003 DENR Order: short term emergency measures to prevent the overtopping of the dam, do the necessary repairs in order to rehabilitate the partially collapsed spillway, and pay the appropriate mine wastes and tailings fee and penalty for the unauthorized discharge of mine wastes/tailings.

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