Department of Civil & Environmental Engineering
Clarkson University

DLBreach (Simplified)

DLBreach is a simplified physically-based Dam/Levee Breach model developed by Wu (2013 & 2016). It can simulate the breaching processes of homogenous and composite earthen embankments due to overtopping and piping in inland and coastal contexts. The model uses a one-way breach for inland dam and levee breaching by unidirectional flows, and a two-way breach for coastal and estuarine levee and barrier breaching, in which flow may reverse.

DLBreach divides the overtopping breaching process into two stages. The first stage is the intensive breaching or erosion stage, in which the breach flow is supercritical, controlled by upstream. The second stage is the general breach or inlet evolution stage, in which the flow is subcritical, controlled by downstream or both upstream and downstream. In the first stage the breach flow is calculated using the weir flow equation, and in the second stage the breach flow is calculated using the Keulegan equation. The Keulegan equation is the simplified energy equation for steady nonuniform flow with local head loss due to channel contraction and expansion, added the wind driving force to consider the effect of wind. In the case of piping, the breach flow is determined using the orifice flow equation.

The model approximates the overtopping breach cross-section as a trapezoid, and the breach longitudinal section as a flat top connected with a headcut (vertical drop) or a straight slope for cohesive and non-cohesive homogeneous embankments, respectively. For composite embankment with a clay core, the downstream becomes two straight slopes along the core and shoulder after the core is exposed. The piping breach is approximated as a flat pipe with rectangular cross-section until the pipe top collapses, and then overtopping takes place. A non-equilibrium total-load transport model and a cohesive sediment erosion model are adopted for non-cohesive and cohesive embankment erosion, respectively. The time-averaged headcut migration rate is determined using the energy-based formula of Temple (1992). Stabilities of the side slope, pipe top, headcut and clay core are analyzed by comparing the driving and resistance forces. A planar slope stability analysis model is developed to find the steepest stable slope and its corresponding failure slope, and then set the breach side slope as the average of these two. The model allows subbase erosion and incomplete breach. It can consider breaching at one side or in the middle of embankment length.

DLBreach is able to handle dam and levee breaches by adopting various routing algorithms for head and tail water levels. For dam breach, the reservoir water level is determined by using the water balance equation. For levee breach, the upstream water level can be set as the measured time series or calculated using another hydrodynamic model. The downstream water level is given as measured time series, or determined by assuming a uniform channel flow or solving the water balance equation for the receiving water body such as bay or lake. DLBreach considers surge overflow and wave overtopping discharge, wave setup, wind setup, and longshore sediment transport in cases of coastal levee and barrier breaches.

DLBreach has been extensively tested by using 50 sets of dam breach data and 4 sets of levee/barrier breach data from laboratory experiments and field case studies. The calculated peak breach discharges, breach widths, and breach characteristic times agree generally well with the measured data. It has been also compared with other embankment breach models, such as NWS BREACH, HR BREACH and WinDAM B, and demonstrated to have more capabilities.  

DLBreach Technical Report: pdf logo

DLBreach Input and Output Format: pdf logo

DLBreach Executable Code: Download zip file [32 kB]

DLBreach Test Cases: Download zip file [24 kB]

References:

W. Wu (2013). “Simplified physically based model of earthen embankment breaching.” J. Hydraul. Eng., 139(8), 837-851.

W. Wu (2016). “Introduction to DLBreach A Simplified Physically-Based Dam/Levee Breach Model, version 2016.4.” Technical Report, Department of Civil and Environmental Engineering, Clarkson University, NY, p. 119.