Modification Of Dams To Accommodate Major Floods

During the life of a dam, changes in safety standards, legislation and land use will inevitably occur, and functional deterioration may also appear. To meet these challenges, these Proceedings from a panel of international experts assess, define and re-evaluate the design criteria for the construction of dams and the many attendant issues in on-going maintenance and management. Authors include international specialists: academics, professionals and those in local government, utilities and suppliers. Practitioners from these same fields will find the book a useful tool in acquiring a comprehensive knowledge of managing and retrofitting dams, so that they can continue to meet society's needs.

Prepared by the Task Committee on Overtopping Protection of the Hydraulics Division of ASCE. This report summarizes the results of an inventory and evaluation of innovative spillway designs and overtopping protection systems developed to provide cost-effective safety modifications for existing dams. The information in this report, which covers pertinent projects in all stages from initial design through construction and operation, was derived from a literature search and a direct survey of the engineering community involved in dam safety modifications. The report contains a brief review of procedures to be used for assessment of the consequences of dam failure and the associated risks is presented for development of the design flood. This is followed by a discussion of innovative spillway designs and the state of the art in dam overtopping protection alternatives. ForØspillway design, this report especially focuses on the use of labyrinth spillways and fuseplug embankments. For overtopping protection systems, the report assesses roller-compacted concrete and precast concrete blocks for smaller dams and cast-in-place reinforced concrete slabs for larger dams. Nonstructural alternatives such as revised reservoir operating requirements and downstream early warning systems are also addressed.

During the life of a dam, changes in safety standards, legislation and land use will inevitably occur, and functional deterioration may also appear. To meet these challenges, these Proceedings from a panel of international experts assess, define and re-evaluate the design criteria for the construction of dams and the many attendant issues in on-going maintenance and management. Authors include international specialists: academics, professionals and those in local government, utilities and suppliers. Practitioners from these same fields will find the book a useful tool in acquiring a comprehensive knowledge of managing and retrofitting dams, so that they can continue to meet society's needs.

Earthen levees are extensively used to protect the population and infrastructure from periodic floods and high water due to storm surges. The causes of failure of levees include overtopping, surface erosion, internal erosion, and slope instability. Overtopping may occur during periods of flooding due to insufficient freeboard. The most problematic situation involves the levee being overtopped by both surge and waves when the surge level exceeds the levee crest elevation with accompanying wave overtopping. Overtopping of levees produces fast-flowing, turbulent water velocities on the landward-side slope that can potentially damage the protective grass covering and expose the underlying soil to erosion. If overtopping continues long enough, the erosion may eventually result in loss of levee crest elevation and possibly breaching of the protective structure. Hence, protecting levees from erosion by surge overflow and wave overtopping is necessary to assure a viable and safe levee system. This book presents a cutting-edge approach to understanding overtopping hydraulics under negative free board of earthen levees, and to the study of levee reinforcing methods. Combining soil erosion test, full-scale laboratory overtopping hydraulics test, and numerical modeling for the turbulent overtopping hydraulics. It provides an analysis that integrates the mechanical and hydraulic processes governing levee overtopping occurrences and engineering approaches to reinforce overtopped levees. Topics covered: surge overflow, wave overtopping and their combination, full-scale hydraulic tests, erosion tests, overtopping hydraulics, overtopping discharge, and turbulent analysis. This is an invaluable resource for graduate students and researchers working on levee design, water resource engineering, hydraulic engineering, and coastal engineering, and for professionals in the field of civil and environmental engineering, and natural hazard analysis.

First published in 1995, the award-winning Civil Engineering Handbook soon became known as the field's definitive reference. To retain its standing as a complete, authoritative resource, the editors have incorporated into this edition the many changes in techniques, tools, and materials that over the last seven years have found their way into civil

Labyrinth spillways are almost as old as dam engineering. In spite of the fact that they appear as a very good technical-economical compromise, only 0.1% of large dams are equipped with such weirs. The main reason for this is that traditional labyrinth weirs usually cannot be installed on top of concrete gravity dams as they require a large foundat