  Dam failures occur worldwide, often from factors including aging structures,
extreme hydrologic loading, and design oversights related to the changing
climate. Understanding and mitigating risk to downstream inhabited areas
require developing and improving low-cost high-fidelity tools, such as
numerical models, which allow emergency managers to predict the consequences of
dam failures better. Two-dimensional (2D) depth-averaged hydraulic models can
provide valuable insights into the importance of breach parameters or
downstream flow characteristics, but historical studies considering historic
failures using real topographies are less common in literature. This study
compares Geoclaw, a 2D hydraulic model with adaptive mesh refinement
capabilities, to an industry-standard software HEC-RAS (Hydrologic Engineering
Center - River Analysis System) using the 1976 Teton Dam failure as a case
study. The suitability of Geoclaw for dam failure modeling is determined based
on its capability to resolve inundation extent and flood wave arrival times.
This study performs sensitivity analyses of the HEC-RAS model to compare an
instantaneous dam breach assumption with a time-dependent breach formation for
quantifying the model uncertainty. We find the 2D Geoclaw dam-break model
results compare reasonably with historical gauge and field observational data
and HEC-RAS results. The model demonstrates stability and relatively low
computational costs. Our findings highlight opportunities for future work, with
the Geoclaw software performance supporting continued studies to evaluate
performance. Outcomes of this study will assist dam owners, floodplain
managers, and emergency managers by providing an additional tool for estimating
the impacts of dam failures to protect lives and infrastructure downstream.
