Kontakt/ Impressum · 

Arthur H. Walz, Jr.

United States Society on Dams

Opportunities - Development and Management of Water Resources

For over 5000 year, dams have provided the necessary water to sustain the population.Following World War II economic development throughout the world was accompanied by phenomenal construction of infrastructure systems.The most significant period for dam construction occurred between the 1950 and 1980 and reached a peak in the decade beginning in 1970 when about 5400 large dams were put into operation.As this economic development continued, the world population became aware of the price that was being paid for this development.Today people of the world are looking for a balance between the project benefits and the environment for water resources projects.People are now asking for a holistic approach to watershed management.The World Commission on Dams Report has recommended considerations for the planning process for water resource projects.At the same time the world population continues to grow and sufficient quantities of water and energy are not available when and where they are needed.All of these trends offer opportunities for ICOLD and it’s member countries to optimize water resources projects to meet regional and national needs.


waltz 1Water remains the vital resource to sustain civilization around the world.Unfortunately, it is not evenly distributed over the world by season or location.Some parts of the world are subject to sever drought, thus making water a scarce and precious commodity.Other parts of the world experience significant precipitation that causes floods that result in loss of life and property.In some regions of the world, sustainability of life is threatened by the imbalance between the demands and available supplies of water, food and energy.

The economic development following World War II was accompanied by phenomenal construction of infrastructure systems throughout the world.Dam construction reached a peak in the 1970s.As this economic development continued, the world population became aware of the price that was being paid for this development.Today the people are looking for a balance between the benefits and the environment for water resources projects.They are also looking for an equal distribution of the benefits for the entire population in the region.People are asking for a holistic approach to watershed management.At the same time the world population continues to grow and sufficient quantities of water and energy are not available when and where they are needed.

Throughout the history of the world, dams and reservoirs have been used successfully in collecting, storing and managing water needed to sustain civilization.Dams and reservoirs are an integral part of our infrastructure and they can be compatible with the social and natural environment of the watershed and the region.The challenge for the future will be the utilization of dams and reservoirs in conjunction with the climate, environment and land use for the prudent management of the world’s water resources as part of each nation’s social and economic development goals.All of these conditions and trends present considerable opportunities for ICOLD and it’s member countries to optimize water resources projects to meet regional and national needs.

II.Public and Private Statements on Water Resources

a.The World Commission on Dams Report

After several years of work, the World Commission on Dams has released its report in November 2000.The specific findings of the World Commission are as follows:

  • Dams have made a significant contribution to human development
  • In some cases, a high price was paid for the benefits
  • Unequal distribution of benefits
  • Need to assess options with those involved
  • Develop the options that represent stakeholder agreement on meeting the national and regional needs
The report goes on to recommend guidelines to improve the social, environmental, governance and compliance aspects of water resources project development.These recommendations should not to be viewed as specific requirements, but rather as tools that can be applied to assist and support the decision making process.While some of these recommendations will require more time and effort in the planning and design process, many anticipated that the end product would be better projects that provide greater benefits to more people.
b.What the People of the United States Have Said about their Nation’s Water Resources
Between 2000 and 2001, the Corps of Engineers invited Americans to participate in a dialogue about the challenges for development and management of the nation’s water resources for the 21st century.The purpose of these forums was to provide the citizens an opportunity to voice their thoughts and concerns about water resources needs, problems and opportunities and to express opinions on what the federal role should be in addressing water resources needs in the next century.A cross section of stakeholders from all geographic areas participated and here is a summary of what they expressed by topic:
1)Restoring and protecting the environment:
  • Revise the Federal planning policy to make the environment an equal goal with economic benefits in project selection.
  • Create cost-sharing incentives to encourage environmental benefits.
  • Create consistency among federal agencies in environmental regulations, especially regarding wetlands.
  • Assure that unavoidable environmental impacts are fully mitigated.
  • Assess and monitor: environmental health, test mitigation techniques, and develop environmentally friendly technologies.
  • Educate the public on environmental issues.

2)Management in watersheds:
  • Analyze water resources comprehensively at a watershed level.
  • Assist in the development of regional "visions" for each major watershed.
  • Help identify watershed-level goals that can be implemented locally.
  • Seek water resources solutions for ecosystem restoration and environmental sustainability along with economic development.
  • Coordinate watershed planning involving all stakeholders and all agencies (Federal, state, and local).
  • Create forums and conflict resolution mechanisms.
  • Help to identify issues for integrated management and planning, including storm water, non-point source pollution, water supply, wetlands, sedimentation, and ecosystem restoration.
3)Floodplain management:
  • Update floodplain maps.
  • Use both structural and non-structural means to reduce flood damages.
  • Achieve more synergy across government programs for better floodplain management, prevention, and response.
  • Discourage future development in floodplains.
  • Promote watershed planning and work for balanced, environmentally sustainable flood solutions.

III.The Current Situation

a.Population of the World
The world population in 2000 was 6.153 billion and continues to grow at an annual rate of 77.3 million.The projection for the world population is as shown on figure 1.A large portion of this growth is in the arid portions of the world – Africa, and Asia.This continues to place a significant demand on water, food and energy.Wise development and management of a nation’s water resources is the cornerstone to meeting The World Bank’s mission and goal to reduce poverty and improve living standards in the world.
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Figure 1.World Population

b.Population Growth in the United States
Since 1970, the population of the United States has grown by about 4%.At the same time significant demographic changes have occurred.People have migrated from the northern states to the south and west where normal precipitation is less and water is scarce (see table 1.).This movement has put a considerable demand storage facilities and distribution systems.

North East
North Central
203.3 million
24 %
31 %
28 %
17 %
281.4 million
18 % (-)
35 % (+)
22 % (-)
25 % (+)
Table 1.Population and Distribution Trend in the United States
c.Flood Damages in The United States
Annual flood losses in the United States continue to worsen despite 75 years of federal flood control programs and 30 years of the National Flood Insurance Program as shown on the graph in figure 2.Today, the average annual flood losses in the United States are about .0 billion.While current flood control structures and flood insurance have made progress in reducing flood damages, damages continue to rise.This is a result of shifts in population and at risk development in the floodplain.More structural and nonstructural flood control measures are needed along with stronger flood plain management.Enforcement and compliance of zoning in the floodplain is also a critical part of this effort.
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Figure 2.Average Annual Flood Damage in the United States

d.Development in the watershed
Development in the watershed has resulted in increased runoff and loss of groundwater recharge.This condition has changed small localized flooding into significant flood events.As the paved area increases from development, more structural measures are required to prevent damages.The changes in runoff and percent of precipitation going to groundwater from development in the watershed can be seen in table 2.Evaporation is not included.

in %
Absorbed Runoff
in %
Percent to Groundwater
Natural cover 10 25 25
20 % paved 20 20 20
50 % paved 30 20 15
75 % paved 55 10 5

Table 2.Increased Runoff with Increased Construction as a % of Precipitation
e.Demand for Energy

The availability of energy is essential to a nation’s socio-economic development.Worldwide energy consumption continues to rise with new development and increased population.Energy that is clean, dependable, efficient and renewable is a basic requirement in today’s social, political and physical environment.Hydropower meets these requirements and is underutilized in many parts of the world.Opportunities for expansion of hydropower exist in most parts of the world as can be seen in table 3.

Electrical Consumption
In billion kW/hours
Installed Capacity
Region Consumption Hydropower as a percent of Total
United States 3,234.9 12 %
Central & South America 699.5 63 %
Western Europe 2606.2 23 %
Africa 366.6 22 %
Asia 3480.2 18%

Table 3.Energy consumption and Electrical Capacity in the world
f.Concern for Environmental Conservation
Managing water resources in a river basin has an impact on its natural water cycle.The scale of the impact depends on the actual size and natural condition of the area to be developed and the extent of development.Concerns about environmental issues and implementation of mitigation measures, are essential elements in the planning of a project.This includes: clearing of vegetation in the area to be flooded, multi-level outlet structures to optimize downstream water temperature and quality, provisions for the migration of fish and other aquatic organisms, and operational rules for regulating downstream flows at critical times to protect habitat for reproduction or migratory routes.Appropriate site selection, together with the implementation of these techniques, will result in both new and rehabilitated projects that minimize unacceptable environmental impacts.
g.Dam Safety Modifications

As a result of several dam failures in the United States in the late 1970s, the Corps of Engineers was directed to develop an inventory of dams in the United States and inspect certain non-federal dams in the inventory.In 1981 the inventory contained 68,153 dams.A total of 8,188 of these were inspected and 2,925 were found to be unsafe.Of the 2,925 dams, 2351 or 80% were unsafe due to inadequate spillway capacity.By December 2000, the number of dams in the inventory has grown to 82,704 and only some of the deficiencies have been corrected.
Several alternative plans to increase spillway discharge capacity are normally considered in conventional modifications.They are:
  • An auxiliary spillway
  • Lined overflow section of the dam
  • Raising of the dam
  • Modification to the existing spillway
  • Combinations of auxiliary spillway, spillway modification and raising the top of dam

An auxiliary spillway provides flexibility for discharge capacity and requires significant disturbance to the environment.Control of surface erosion during construction can also be a problem.A lined overflow section offers considerable discharge but requires excavation in the embankment and loss of vegetation and ground cover.A dam raising increased the flood pool level and any dam raising over about three feet requires considerable borrow excavation for the required embankment fill.A modification to the existing spillway offers the greatest potential for cost effectiveness and minimal disturbance to the surrounding environment.

1)Environmental Concerns and Issues Related to Dam Safety Modifications

The goal is to maintain a clean and healthy watershed during and after the project modification.The issue is to avoid adverse impacts on the environment during and after construction.

The most important environmental consideration is to avoid disturbing or clearing of natural vegetation and ground cover both during construction and for the long term.The effect of decreasing vegetation increases the overall imperviousness of the watershed area, which leads to changes as well as increased runoff characteristics.It can also increase local and downstream erosion.It is also very important to control erosion and sedimentation during the construction activities.The construction sequence must address maintaining downstream water quality during all phases of construction.The modification must also be sensitive to fish and other aquatic organisms.Careful planning and public involvement is required to ensure mitigation of other impacts.The challenge is to select a modification that minimizes environmental impacts.

IV.Opportunities in the Development and Management of Water Resources

a.Opportunities in the " Watershed" Approach

The watershed or river basin is defined by hydrology and transcends national, political, social and economic boundaries making it the basic element for management of water resources and the ecosystems.The watershed approach is characterized by:

  • Defined by natural hydrology, not by social or political boundaries, which makes it the ideal management element for water resources.A watershed generally includes lakes, rivers, estuaries, wetlands, streams, and the developed areas.Ground water is also an area of consideration.
  • Planning in the watershed must include sound science as well as engineering.Sound scientific data, processes and engineering criteria and techniques are critical to the planning process.Management includes prioritization of watershed problems, developing solutions and action plans and after implementation, evaluating their effectiveness.
  • Partnerships and stakeholder involvement are essential to facilitate management and optimize benefits.It is important to involve all the affected interests in designing and implementing goals for the watershed.Watershed teams may include representatives from all levels of government, public interest groups, industry, academic institutions, private landowners, concerned citizens and others.
Therefore, the watershed approach involves:

  • Alignment of an organization or commission along the watershed boundaries
  • Partnership among federal, state and local governments and organizations
  • Public awareness and involvement
  • Monitoring of the system
  • Periodic assessment and evaluation of the watershed – changes in reservoir operation, regulations and laws.

The traditional approach of water resource development that includes the basic purposes of water supply, irrigation, navigation, hydropower and recreation must be expanded to include the following:

  • Water quality
  • Water management(flood and drought)
  • Climate assessment
  • Land use
  • Groundwater management
  • Maintaining the habitat
  • Maintaining and enhancing the environment

b.Opportunities in Hydropower

Hydropower is a clean and renewable source of energy.Only 20% of the available electricity in the world is produced by hydropower.Opportunities for increasing the energy supply from improving the efficiency at existing plants as well as adding new facilities at existing dams.In North America, 19 new power plants ranging in size from 37 kW to 108MW were placed in operation in 1999 and 2000.The total capacity was 310 MW at a capital investment ofmillion.Rehabilitation of existing facilities is being accomplished to ensure reliable delivery of electricity and to improve the efficiency of older units.Currently, in the United States alone, the owners of about 130 plants are rehabilitating the units or have plans to begin in the near future.In Canada, more than 45 rehabilitation projects are underway or planned.

The Tennessee Valley Authority (TVA) is continuing with its Hydro Modernization Program and has completed rehabilitation of 92 of its 113 hydroelectric plants.When this program is complete, TVA will have added 720 MW of capacity to its generating system.

c.Opportunities in Environmental Conservation

The goal is to achieve clean and healthy watersheds that support aquatic life, economic development and human needs. This goal will best be met by encouraging and supporting comprehensive water resource management that is tailored to the regional and local needs.Environmental conservation includes mitigation and enhancement for new projects, maintaining the existing conditions and restoration where appropriate.

A multipurpose project in southern Germany designed and constructed by the Bavarian Authority for Water Resources Management (Wasserwirtschaftsamt - Kempten) is an excellent example of optimizing the environmental conservation and enhancement.The primary project purposes are flood control, water supply and hydropower, however recreation and environmental enhancements have been added.Parts of the reservoir area are restricted for wetland development, aquatic habitat and animals.Islands, a small dam to protect the wetlands from reservoir fluctuations and an uneven shoreline were created.This project is now a success story of developing water resources and enhancing the environment.

d.Opportunities in Dam Safety Modifications

Providing modifications to increase spillway capacity to accommodate new inflow design floods presents the engineer with real challenges and opportunities.The goal is to select the most cost effective and environmentally responsible alternative for the modification.The cost estimates for each alternative must reflect realistic costs to mitigate the impacts on the natural environment.This alternative should minimize damage to the environment by:

  • Minimal or no construction outside of the footprint of the dam and spillway
  • Minimal or no disturbance to ground cover and erosion during and after construction
  • Minimize erosion during construction
  • Provide adequate control of sedimentation
  • Minimize impact on water quality during construction
  • Minimal or no impact during future operation

Environmental Assessment of the Modification Alternatives

A comprehensive environmental assessment must be made for all of the alternatives considered.This assessment evaluates the conditions and impacts for both the "with" and "without" modification at the dam, and is accomplished in accordance with state and federal regulations.The extent and permanence of any detrimental effects of the modification on the project and watershed is a critical part of this assessment.Public involvement in the proposed modification is also part of this process.Each alternative should be assessed with the following environmental criteria:

  • Avoids adverse impacts to the environment
  • Mitigates any unavoidable environmental impacts
  • Maintains water quality and the ecosystem during and after the modification
  • Achieves no net loss in environmental values and functions

Many owners have chosen to install a "fusegate system" in their existing or new spillway will provide reliable and safe operation for the increased inflow design flood.It is also the environmentally responsible solution.This is an innovative and cost effective system that can increase both safety and storage capacity of dams.It is installed rapidly and requires minimum long-term maintenance.This type of modification achieves no net loss in environmental values and satisfies environmental concerns of the public.The Corps of Engineers have conducted model tests on fusegates for use in terminus Dam, California and have plans for their use at several other projects.

Lussas dam, an irrigation facility in southern France, was modified to increase the storage by 33 percent for about 10 percent of the cost of a conventional modification.In addition, the fusegates required no construction outside of the footprint of the spillway and did not require raising of the dam.It now has greater storage capacity and meets all spillway capacity requirements

e.Opportunities in Public Awareness and Education

The world is in an era where vast amounts of information are available through the all versions of the media; the internet and publications can have a significant impact on the knowledge and perceptions of society.The issue of expansion and rehabilitation of the world’s infrastructure, and the debate about the need for and use of dams is an excellent example of this worldwide pheromone.Therefore, it is essential that ICOLD migrate to a more "open system" approach, broadening and strengthen its scope of public awareness and educational efforts while still maintaining its high quality technical activities.

The success and public acceptance of any program or project is a direct result of the public awareness and education of all aspects of that program or project.As a result of the WCD report and public interest in the environment and water resources, ICOLD and its member countries have an opportunity to make the public aware of the success that can be achieved in development and management of water resources.We should:

  • Use the Communications Plan and Strategy to strengthen their public awareness and media relation’s efforts.The public must be made aware of the challenges and opportunities that exist relative to the world’s water and the benefits from the storage and management of water in river basins.Describe the role of dams in river basin management in meeting water demands and preventing floods their interrelationship with the environment.
  • Must engage in more interaction and co-ordination of joint efforts with other international water-resource oriented professional societies.
  • Should provide reliable facts and information to political decision-making bodies, financing agencies, environmental lobby groups and organizations, and to the general public, on the benefits of prudent utilization of water, especially by storage in reservoirs and the proper operation of dams.

Education is as important as awareness.Educational efforts and programs should be taken to the public, universities, high schools and grade schools.Our children are being taught the values of the environment in grade school.It is important to expose them to accurate and reliable information on water resources development.An opportunity exists for ICOLD members should use presentations, lectures, games and scale models to educate school children as well as the public.


As we enter the 21st century we must remember that about one quarter of the world’s population is without clean drinking water and there is insufficient water to sustain agriculture.There is also an insufficient amount energy to sustain adequate standard of living and support the necessary economic development in many parts of the world.Experience by ICOLD and it’s member countries in water resources development throughout the world can be summarized as follows, and should be included in discussions that address meeting the worldwide water and energy needs:

  • Dams have made a significant and beneficial contribution to national development, but like all infrastructure projects, there have been social and environmental tradeoffs.
  • The technology used in dam engineering and construction has progressed and will continue to advance so that new projects and modifications to existing dams are efficient and cost effective to meet the identified needs as well as environmentally and socially responsible.
  • Significant quantities of water and energy are now required to eliminate poverty and sustain national economic development in the world.
  • As the world’s population continues to grow and a higher standard of living is sought by developing countries, the need for water and energy will increase.
  • Dams will continue to play a significant and beneficial role in the development and management of water in river basins.
  • Public interest and involvement in all phases of water resources projects is needed and presents opportunities for the planners and designers to create innovative solutions that maximize the full range of project benefits to best meet regional and national needs.
  • The watershed approach provides coordinated efforts and management.It facilitates the assessment of structural needs – construction of new dams, rehabilitation of existing dams, adding or changing the project purposes and removal of smaller dams that no longer serve a purpose.
The challenge for the future will be the utilization of dams and reservoirs in the watershed in conjunction with the climate, environment and land use for the wise management of the world’s water resources as part of each nation’s social and economic development goals.ICOLD and its member countries must take this challenge and associated opportunities to improve and enhance dam design and construction for water resources projects.