Text 18A3-I

The roar of a waterfall suggests the power of water. Rampaging floodwaters can uproot strong trees and twist railroad tracks. When the power of water is harnessed, however, it can do useful work for humans.

Since ancient times, people have put the energy in the flow of water to work. They first made water work for them with the waterwheel, a wheel with paddles around its rim. Flowing water rotated the waterwheel, which in turn ran machinery that was linked to it. Today, new kinds of waterwheels – turbines – spin generators that produce electricity. Electricity from waterturned generators is known as hydroelectricity.

By building a dam across a river, the natural upstream water level is elevated and a difference in head is created that can be used to drive turbines and generate electricity. A large upstream reservoir may balance seasonal water flow; rain or melted snow can be stored in the reservoir during the wet season to provide electricity during dry seasons.

Waterpower is distributed unevenly among the continents and nations of the world. Europe and North America have developed much of their waterpower. Asia, South America, and Africa have abundant waterpower potential, but while countries such as China and Brazil have become leading hydroelectric producers, much of the waterpower resource on those continents remains undeveloped.

Elizabeth Lachner. Hydroelectricity. Rosen Publishing Group, 2018 (adapted).

Text 18A3-I

The roar of a waterfall suggests the power of water. Rampaging floodwaters can uproot strong trees and twist railroad tracks. When the power of water is harnessed, however, it can do useful work for humans.

Since ancient times, people have put the energy in the flow of water to work. They first made water work for them with the waterwheel, a wheel with paddles around its rim. Flowing water rotated the waterwheel, which in turn ran machinery that was linked to it. Today, new kinds of waterwheels – turbines – spin generators that produce electricity. Electricity from waterturned generators is known as hydroelectricity.

By building a dam across a river, the natural upstream water level is elevated and a difference in head is created that can be used to drive turbines and generate electricity. A large upstream reservoir may balance seasonal water flow; rain or melted snow can be stored in the reservoir during the wet season to provide electricity during dry seasons.

Waterpower is distributed unevenly among the continents and nations of the world. Europe and North America have developed much of their waterpower. Asia, South America, and Africa have abundant waterpower potential, but while countries such as China and Brazil have become leading hydroelectric producers, much of the waterpower resource on those continents remains undeveloped.

Elizabeth Lachner. Hydroelectricity. Rosen Publishing Group, 2018 (adapted).

Text 20A4-I

Fresh water is a precious resource, and water from rivers, streams, and lakes has often been regarded as an economic commodity in the United States as in much of the world. Water is essential not only for human consumption and for a variety of domestic purposes, but for fire protection, military defense, transporting people and goods, irrigating farmlands, manufacturing, and generating power. The great rivers and their tributaries in the United States are the primary source of the water bounty and are major symbols of American regionalism, ultimately binding together disparate areas into a powerful whole.

American rivers were symbols of a burgeoning nation in the 18th and the 19th centuries. They inspired romantic renderings at the hands of artists, and in some cases, they were depicted as detailed landscape features with physical and even human qualities. But at times they were regarded as untapped or underutilized resources, raw material waiting to be harnessed, managed, and exploited for human benefit. In the neoclassical tradition of the 18th and early 19th centuries, the ‘proper’ channel for a river was not necessarily the one it has carved for itself: by means of canals and locks it can be guided by men along a straight and level line, thereby improving upon natural design. “Rivers, therefore, were most attractive when they yielded to humanity’s needs, whether as mechanisms of transportation or as sites for nascent towns.” For aesthetic and for practical reasons, wild rivers served little purpose, as historian Theodore Steinberg noted:

“As the 19th century progressed, a consensus emerged on the need to exploit and manipulate water for economic gain. A stunning cultural transformation was taking place, a shift in people’s very perception of nature. By the latter part of the 19th century, it was commonly assumed, even expected, that water should be tapped, controlled, and dominated in the name of progress — a view clearly reflected in the law”.

Steamboats, canals, and dams became the technologies of choice to accomplish those goals.

David Billington, Donald Jackson, and Martin Melosi. The History of Large Federal Dams: Planning, Design and Construction.

Text 3A4

During the last century water infrastructure projects involving large dams played a major role in the socio-economic transformation of many countries. At the same time, in a significant number of cases the benefits were not shared equitably, and the negative impacts on the environmental and sociocultural structures were excessive. In some cases their economic performance was questionable. Diverging views have arisen on the merits and demerits of dams, the roles they play, and their alternatives in providing water and energy services. However, recognition that such roles are complementary rather than mutually exclusive has been growing as the dam debate has moved forward.

It is envisaged that, as part of the global effort to improve water and energy supplies, more dams will be constructed, especially in developing countries, alongside other diverse alternatives. There will, consequently, be a need to enhance the benefits of dams and avoid many of their drawbacks by applying better decision-making processes within the overall framework of sustainability. There are complex issues around the planning and management of dams in the context of sustainable development which will need to be adequately considered and addressed to achieve sustainable outcomes.

Dealing with the environmental and social challenges within the context of meeting water and energy needs is at the heart of the sustainability of projects involving dams. Dams are one of the options, structural or non-structural, available to meet specific water or energy needs. In many cases water and energy services are best provided through a mix of options. Each case is different. A decision to build a dam should emerge after a comprehensive assessment of the full range of available options, giving appropriate consideration to all aspects of sustainability.

United Nations Environmental Programme. Dams and Development: Relevant Practices for Improved Decision-making. Nairobi: The Secretariat of the Dams and Development Project, 2007. p. 10-1 (adapted).

Text 3A4

During the last century water infrastructure projects involving large dams played a major role in the socio-economic transformation of many countries. At the same time, in a significant number of cases the benefits were not shared equitably, and the negative impacts on the environmental and sociocultural structures were excessive. In some cases their economic performance was questionable. Diverging views have arisen on the merits and demerits of dams, the roles they play, and their alternatives in providing water and energy services. However, recognition that such roles are complementary rather than mutually exclusive has been growing as the dam debate has moved forward.

It is envisaged that, as part of the global effort to improve water and energy supplies, more dams will be constructed, especially in developing countries, alongside other diverse alternatives. There will, consequently, be a need to enhance the benefits of dams and avoid many of their drawbacks by applying better decision-making processes within the overall framework of sustainability. There are complex issues around the planning and management of dams in the context of sustainable development which will need to be adequately considered and addressed to achieve sustainable outcomes.

Dealing with the environmental and social challenges within the context of meeting water and energy needs is at the heart of the sustainability of projects involving dams. Dams are one of the options, structural or non-structural, available to meet specific water or energy needs. In many cases water and energy services are best provided through a mix of options. Each case is different. A decision to build a dam should emerge after a comprehensive assessment of the full range of available options, giving appropriate consideration to all aspects of sustainability.

United Nations Environmental Programme. Dams and Development: Relevant Practices for Improved Decision-making. Nairobi: The Secretariat of the Dams and Development Project, 2007. p. 10-1 (adapted).

Text 3A4

During the last century water infrastructure projects involving large dams played a major role in the socio-economic transformation of many countries. At the same time, in a significant number of cases the benefits were not shared equitably, and the negative impacts on the environmental and sociocultural structures were excessive. In some cases their economic performance was questionable. Diverging views have arisen on the merits and demerits of dams, the roles they play, and their alternatives in providing water and energy services. However, recognition that such roles are complementary rather than mutually exclusive has been growing as the dam debate has moved forward.

It is envisaged that, as part of the global effort to improve water and energy supplies, more dams will be constructed, especially in developing countries, alongside other diverse alternatives. There will, consequently, be a need to enhance the benefits of dams and avoid many of their drawbacks by applying better decision-making processes within the overall framework of sustainability. There are complex issues around the planning and management of dams in the context of sustainable development which will need to be adequately considered and addressed to achieve sustainable outcomes.

Dealing with the environmental and social challenges within the context of meeting water and energy needs is at the heart of the sustainability of projects involving dams. Dams are one of the options, structural or non-structural, available to meet specific water or energy needs. In many cases water and energy services are best provided through a mix of options. Each case is different. A decision to build a dam should emerge after a comprehensive assessment of the full range of available options, giving appropriate consideration to all aspects of sustainability.

United Nations Environmental Programme. Dams and Development: Relevant Practices for Improved Decision-making. Nairobi: The Secretariat of the Dams and Development Project, 2007. p. 10-1 (adapted).

Text 3A4

During the last century water infrastructure projects involving large dams played a major role in the socio-economic transformation of many countries. At the same time, in a significant number of cases the benefits were not shared equitably, and the negative impacts on the environmental and sociocultural structures were excessive. In some cases their economic performance was questionable. Diverging views have arisen on the merits and demerits of dams, the roles they play, and their alternatives in providing water and energy services. However, recognition that such roles are complementary rather than mutually exclusive has been growing as the dam debate has moved forward.

It is envisaged that, as part of the global effort to improve water and energy supplies, more dams will be constructed, especially in developing countries, alongside other diverse alternatives. There will, consequently, be a need to enhance the benefits of dams and avoid many of their drawbacks by applying better decision-making processes within the overall framework of sustainability. There are complex issues around the planning and management of dams in the context of sustainable development which will need to be adequately considered and addressed to achieve sustainable outcomes.

Dealing with the environmental and social challenges within the context of meeting water and energy needs is at the heart of the sustainability of projects involving dams. Dams are one of the options, structural or non-structural, available to meet specific water or energy needs. In many cases water and energy services are best provided through a mix of options. Each case is different. A decision to build a dam should emerge after a comprehensive assessment of the full range of available options, giving appropriate consideration to all aspects of sustainability.

United Nations Environmental Programme. Dams and Development: Relevant Practices for Improved Decision-making. Nairobi: The Secretariat of the Dams and Development Project, 2007. p. 10-1 (adapted).

Text 3A4

During the last century water infrastructure projects involving large dams played a major role in the socio-economic transformation of many countries. At the same time, in a significant number of cases the benefits were not shared equitably, and the negative impacts on the environmental and sociocultural structures were excessive. In some cases their economic performance was questionable. Diverging views have arisen on the merits and demerits of dams, the roles they play, and their alternatives in providing water and energy services. However, recognition that such roles are complementary rather than mutually exclusive has been growing as the dam debate has moved forward.

It is envisaged that, as part of the global effort to improve water and energy supplies, more dams will be constructed, especially in developing countries, alongside other diverse alternatives. There will, consequently, be a need to enhance the benefits of dams and avoid many of their drawbacks by applying better decision-making processes within the overall framework of sustainability. There are complex issues around the planning and management of dams in the context of sustainable development which will need to be adequately considered and addressed to achieve sustainable outcomes.

Dealing with the environmental and social challenges within the context of meeting water and energy needs is at the heart of the sustainability of projects involving dams. Dams are one of the options, structural or non-structural, available to meet specific water or energy needs. In many cases water and energy services are best provided through a mix of options. Each case is different. A decision to build a dam should emerge after a comprehensive assessment of the full range of available options, giving appropriate consideration to all aspects of sustainability.

United Nations Environmental Programme. Dams and Development: Relevant Practices for Improved Decision-making. Nairobi: The Secretariat of the Dams and Development Project, 2007. p. 10-1 (adapted).

Text 22A4-II

Over the past few years, Peruvian authorities have tried to find ways to manage increasing visitor numbers to the popular site which often had long lines and overcrowding, leaving many tourists unable to enter. Machu Picchu was awarded UNESCO World Heritage status in 1983 and is described by the awarding body as probably the most amazing urban creation of the Inca Empire at its height. It added its giant walls, terraces, and ramps “seem as if they have been cut naturally” into the continuous rock escarpments. The citadel, 130 km from Cusco, was built in the 15t^h as a religious sanctuary for the Incas at an altitude of 2,490 meters.

However, UNESCO also highlighted the challenges faced by the site, which it says requires more stringent management. “Tourism itself represents a double-edged sword by providing economic benefits but also by resulting in major cultural and ecological impacts,” said UNESCO. “The strongly increasing number of visitors to the historic sanctuary of Machu Picchu must be matched by an adequate management regulating access, diversifying the offer, and efforts to fully understand and minimize impacts. A larger appropriate and increasing share of the significant tourism revenues could be reinvested in planning and management.”.

Internet: <https://www.thenationalnews.com> (adapted).

Text 22A4-II

Over the past few years, Peruvian authorities have tried to find ways to manage increasing visitor numbers to the popular site which often had long lines and overcrowding, leaving many tourists unable to enter. Machu Picchu was awarded UNESCO World Heritage status in 1983 and is described by the awarding body as probably the most amazing urban creation of the Inca Empire at its height. It added its giant walls, terraces, and ramps “seem as if they have been cut naturally” into the continuous rock escarpments. The citadel, 130 km from Cusco, was built in the 15t^h as a religious sanctuary for the Incas at an altitude of 2,490 meters.

However, UNESCO also highlighted the challenges faced by the site, which it says requires more stringent management. “Tourism itself represents a double-edged sword by providing economic benefits but also by resulting in major cultural and ecological impacts,” said UNESCO. “The strongly increasing number of visitors to the historic sanctuary of Machu Picchu must be matched by an adequate management regulating access, diversifying the offer, and efforts to fully understand and minimize impacts. A larger appropriate and increasing share of the significant tourism revenues could be reinvested in planning and management.”.

Internet: <https://www.thenationalnews.com> (adapted).