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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : Breaching of small embankment dams:tool for cost-effective determination of peak breach outflow
Breaching of small embankment dams:tool for cost-effective determination of peak breach outflow
Author : ROBERT M. BOES(1), LUKAS VONWILLER(2) & DAVID F. VETSCH(3)
ABSTRACT
Increasing public awareness of flood risk requires more rigorous analyses of the impact of dam failure nowadays. While
until recently the Swiss dam safety legislation prescribed to take into account a sudden failure assuming a standardized
breach geometry for all dam types including earthen embankments, there have been initiatives to consider more
physically-based progressive breach mechanisms for embankment dam failures to determine the peak outflow.
In a study of some 90 small earthen embankment dams (height up to 10 m, reservoir volumes up to 150000 m3) in the
canton of Zurich, Switzerland, both a 2D numerical model and a parametric model have been used to determine outflow
peak discharges due to dam failure by overtopping. The numerical model was calibrated by data from laboratory
modelling, while an existing parametric model was then adapted and implemented based on a systematic parametric
variation using the numerical model. The parametric model was validated based on field test data from the European
IMPACT project.
A comparison of breach outflow peaks using the standard breach and the parametric model revealed that in most cases
the peak outflow is overestimated by the former due to the assumption of an instantaneous breach. A progressive breach
underlying the parametric model appears to be more realistic. However, and more importantly from a risk assessment
point of view, the outflow peaks are underestimated by the standard breach approach for the evaluated reservoirs with
large volumes, independent of dam height, as well as for relatively large reservoirs impounded by low dams.
The parametric model presented herein allows for a quick and efficient calculation of peak breach outflows for small
homogeneous embankment dams. Currently, the model is limited to certain parameter ranges as investigated in the
current research project, but there are plans to extend its range of applicability to allow for a wide-spread use.
File Size : 620,705 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 20/08/2015
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