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Dams and Development
E-Paper Contents
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Home Page of Dams and Development
Foreword
I. Why an e-paper on dams and development?
II. Assessing options
III. Participatory processes
IV. Social impacts
V. Environmental impacts
VI. Benefit distribution
VII. Dam safety and sustainability
VIII. Existing projects
IX. Improving governance
X. What other organizations say
XI. ADB, Dams, and Development
XII. References
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World Bank Policy on Dam Safety - OP and BP 4.37

The World Bank's Policy on Safety of Dams makes provision for safety of projects it finances including new dams, existing dams and dams under construction. It defines small and large dams and the different provisions required for each category.

Paras 3 and 4 define the types of project to which the policy relates:

'3. The Bank distinguishes between small and large dams.
  1. Small dams are normally less than 15 meters in height. This category includes, for example, farm ponds, local silt retention dams, and low embankment tanks.
  2. Large dams are 15 meters or more in height. Dams that are between 10 and 15 meters in height are treated as large dams if they present special design complexities-for example, an unusually large flood-handling requirement, location in a zone of high seismicity, foundations that are complex and difficult to prepare, or retention of toxic materials. Dams under 10 meters in height are treated as large dams if they are expected to become large dams during the operation of the facility.
4. For small dams, generic dam safety measures designed by qualified engineers are usually adequate. For large dams, the Bank requires
  1. reviews by an independent panel of experts (the Panel) of the investigation, design, and construction of the dam and the start of operations;
  2. preparation and implementation of detailed plans: a plan for construction supervision and quality assurance, an instrumentation plan, an operation and maintenance plan, and an emergency preparedness plan;
  3. prequalification of bidders during procurement and bid tendering, and
  4. periodic safety inspections of the dam after completion'.

The definition of "large dams" is based on the criteria used to compile the list of large dams in the World Register of Dams, published by the International Commission on Large Dams.

One of the main provisions is appointment of the independent panel of experts. The scope is outlined in para 5:

'The primary purpose of the Panel is to review and advise the borrower on matters relative to dam safety and other critical aspects of the dam, its appurtenant structures, the catchment area, the area surrounding the reservoir, and downstream areas. However, the borrower normally extends the Panel's composition and terms of reference beyond dam safety to cover such areas as project formulation; technical design; construction procedures; and, for water storage dams, associated works such as power facilities, river diversion during construction, shiplifts, and fish ladders'.
ICOLD definition of large dams

The International Commission on Large Dams (ICOLD), established in 1928, defines a large dam as a dam with a height of 15m or more from the foundation. If dams are between 5-15m high and have a reservoir volume of more than 3 million cubic metres, they are also classified as large dams.

Using this definition, the World Commission on Dams estimated there are over 45,000 large dams around the world.


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