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Solving Dam Engineering Challenges

By Luis Berga

The International Commission on Large Dams provides a forum for the exchange of knowledge and experience in dam engineering. Much of this exchange takes place through the work of 24 technical committees. A sampling of committee activities illustrates the breadth and depth of ICOLD’s work.

The International Commission on Large Dams (ICOLD) was founded in 1928. Over the past 80 years, ICOLD has focused on its mission: to advance state-of-the-art science and engineering for the planning, design, construction, operation, and maintenance of safe dams. ICOLD’s 88 member countries represent about 90 percent of the world’s population. ICOLD’s nearly 10,000 members are practicing engineers, geologists, and scientists from governmental and private organizations, consulting firms, universities, laboratories, and construction companies.

To encourage knowledge transfer and to disseminate information, ICOLD has 24 technical committees with a total of more than 400 members. The committees address current technical issues related to the development and management of water resources. The committees produce a variety of work products, including technical bulletins.

To date, ICOLD has published 132 bulletins. To facilitate the spread of the information in the bulletins, bulletins up to No. 100 are accessible, free, on the Internet (www.icold-cigb.net). The more recently published bulletins (No. 101-132) are available for purchase, also at the ICOLD website.

Descriptions of activities of some of the committees illustrate the breadth and depth of ICOLD’s work.

New committees focus onhydro, project planning

Members of the new committee on Dams for Hydroelectric Energy are sharing experiences of developing sustainable hydropower dams, with discussions covering policies and programs developed to promote the role of renewable energies. The committee is focusing specific attention on the effects of new and/or additional uses and demands of existing hydropower dams. Technical issues being discussed include those related to pumped-storage facilities and the incidence of dam and reservoir aging (including reservoir siltation).

Owing to an inadequate level or lack of engineering in the planning process for a water resources project, the option for a multi-purpose dam project is often not considered. In response, ICOLD formed a new committee, Engineering Activities in the Planning Process for Water Resources Projects, to collect and review planning processes for water resources projects. From this review, ICOLD intends to determine the appropriate level and type of engineering activities to include in the planning process for a water resources project.

The committee will publish a position paper and guidelines, “Engineering Activities Associated with the Planning Process for Water Resources Projects,” for distribution to governments of developing countries, the United Nations, the World Bank, and other organizations associated with water resources development.

Focusing on cost savings,small dams, and dam removal

Over the next decade, the annual worldwide investment in dams (mostly in developing countries) will be about US$30 billion. The optimum design of each dam depends on locally available materials, river and foundation conditions, and the local economy. It is difficult to choose the most cost-effective solution, thus most dam designs could be 10 to 20 percent more expensive than the optimum design.

To help dam owners and consultants address this cost-saving issue, the ICOLD committee on Cost Savings in Dam Construction is analyzing the effectiveness of various cost-saving solutions. A bulletin summarizing the committee’s work is expected be published in 2009. The bulletin will feature a comparison of the various contractual methods, with information on the best choices and how to avoid unnecessary extra costs.

Another issue ICOLD is focusing on is that of small dams — those 5 to 15 meters high. There is not as much research and data on the design of small dams as there is for the design of large dams. Yet, all countries have many small dams. It is essential to establish simple rules and procedures for the planning, construction, and maintenance of these dams. The committee on Small Dams is preparing a bulletin providing: a historical review of ancient dams; types of small dams; peculiar features about the design of small earthfill dams; guidelines on surveillance and monitoring of small dams; and guidelines for an emergency action plan that are inexpensive and easy to apply.

A third issue ICOLD is addressing is the removal of dams. As dams age or no longer serve their original purpose, removal may be an option to address issues related to dam safety, economics, or fish passage. The committee on Dam Decommissioning is collecting information on dam removal activity. Information includes: number of dams that have been removed; number of dam removals planned; dam type, height, length, reason for removal, cost of removal, and alternatives considered; how ownership of the dam affects the removal decision; environmental studies and permits required for dam removal; and the primary reasons for dam removal (safety, economics, fish passage).

Addressing technical issues

Many of the ICOLD committees focus on technical issues, including dam design, surveillance, construction, and river sedimentation. The following paragraphs provide examples of the work of these committees.

The committee on Computational Aspects of Analysis and Design of Dams is preparing a new bulletin, “Guidelines for Use of Numerical Models in Dam Engineering.” The committee also is planning to hold a workshop in 2009. Two topics are being considered for this workshop: explanation of recent incidents experienced at high concrete-faced rockfill dams and concrete swelling in arch dams. The committee has organized several such workshops, at which numerical problems are proposed, participants give numerical solutions, and all results obtained are compared. Through past workshops, about 20 problems have been proposed. The committee is contemplating editing the entire collection of problems and solutions and making it available to the worldwide dam community.

Work of the committee on Dam Surveillance includes development of two bulletins: “General Approach on Dam Surveillance” for dam managers and other non-specialists; and “Surveillance Guide” for technical guidance. Topics covered include monitoring system optimization, re-instrumentation for existing dams, and recent developments and future trends in seepage and leakage detection monitoring.

The committee on Dams and Floods is preparing a bulletin that will present the state-of-the-art in integrated flood management. The bulletin will present a review of the methods currently applied, which may be structural and non-structural, and present several case studies demonstrating the efficiency of the methods and the benefits to be derived from such activities. It also will provide recommendations for the application of these methods within the general framework of integrated water resources management. The bulletin is intended to provide a reference for improving the efficiency of flood protection measures, while maximizing the benefits from existing structures.

The committee on Materials for Fill Dams is preparing a bulletin on cutoffs in dam construction. Cutoffs are designed to reduce seepage. Tremendous achievements have been made to ensure the effectiveness of cutoffs, with new techniques developed and the ability to reach greater depths than ever before. This bulletin will provide state-of-the-art practice in the design and construction of this essential dam construction technique under specific foundation conditions.

The committee also is preparing two reports: one on residual soils as foundation and fill material and one on geotextiles. These two reports will provide information on how these materials have been and are being used throughout the world. The reports address specific technical problems associated with these materials, to improve the understanding of their behaviors.

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The committee on Sedimentation of Reservoirs is developing a bulletin, “Reservoir Sedimentation and Sustainable Use of Reservoirs and River Systems.” The bulletin will provide guidelines for the design and operation of dams to limit their effects on river systems. The bulletin covers: the effects on the fluvial morphology of rivers upstream and downstream of dams, the current global state of reservoir sedimentation and the predicted rate of siltation, and managed flood releases and sediment flushing releases. One of the key focuses of the bulletin is to predict future country-specific and regional reservoir sedimentation rates. This information is very importantfor planningof new dams and for operation of existing dams. By understanding the effects of dams on the river flow and morphology, engineers and ecologists can implement measures to help limit these effects.

Getting involved

To learn more about the work of ICOLD’s technical committees or how to get involved, contact ICOLD’s secretary-general Michel De Vivo, in Paris, by e-mail: secretaire.general@icold-cigb. org or by phone: (33) 1-40426824.

Mr. Berga may be reached at ETS Ingenieros de Caminos, c/Gran Capital s/n Modulo D-1, Barcelona 08034 Spain; (34) 93-4016478; E-mail: lluis.berga@upc.edu.

Luis Berga is president of the International Commission on Large Dams and a professor at the Polytechnic University of Barcelona, Spain.


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