Breach Erosion of Earth Dams

Breach Erosion of Earth Dams

Broere, D.

Nieuwenhuis, J.D. (mentor)
Vrijling, J.K. (mentor)
Visser, P.J. (mentor)
Battjes, J.A. (mentor)

Civil Engineering and Geosciences

Hydraulic Engineering

1999-05-01

In this report a breach erosion model for earth dams is presented. Descriptions of historical earth dam failures and data of (field) experiments are used to form a model in which the geometric development of the breach is emphasised. Three components form the basis of this model: 1. A water balance in which the inflow into the upstream reservoir, the storage in this reservoir and the discharge via the breach are related to each other. 2. A descriptor of the sediment entrainment and sediment transport in the breach section. 3. A descriptor of the geometric development of the breach due to the erosive capacity of the water that flows through the breach. The model is based on the breach erosion model for sand dikes BRES (BReach Erosion in Sanddikes, Visser, 1998), which was developed using both field and laboratory experiments. The adjustments to this model are inspired by the main difference between dikes and earth dams. Dikes have a relatively low long body, while earth dams are high and relatively short with respect to this height. This difference makes the description of the development of the initial breach through erosion in vertical direction more important for earth dams. Therefore this vertical erosion is described more in detail than in BRES. The following adjustments are made to the BRES model: 1. The breach section is split up into two parts: a top channel and a downstream channel. Contrary to 'the BRES not only erosion along the downstream channel is taken into account, but erosion along the top channel as well. 2. Enhanced geometric description of the channel along the downstream face of the dam, because it is expected that along this channel most of the erosion will take place. 3. More detailed description of the influence of the supply of side slope material on the rate of erosion in the breach channel. The applicability of the model is verified by using a computer program of the model. Data of the Zwin'94 field experiment was used to calibrate the model. The Teton Dam failure and the Laurel Run Dam failure were used for additional verification. Good agreement between computed and observed values was found for the Zwin'94 experiment and the Teton Dam failure. The breach growth during the Laurel Run Dam failure was overestimated by the model. During the Zwin'94 field experiment there was hardly any erosion along the top, as predicted by the model. In case of the Teton Dam, the model performed better if erosion along the top was taken into account. A sensitivity analysis was performed to show the sensitivity of the model to changes in the input parameters.

breach erosion model
earth dams
sand dikes

http://resolver.tudelft.nl/uuid:5afd41c7-e58a-40e0-9bcb-74d69a0097d7

Student theses

master thesis

(c) 1999 Broere, D.