Abstract
Development and simulation of synthetic hurricane tracks is a common
methodology used to estimate hurricane hazards in the absence of empirical
coastal surge and wave observations. Such methods typically rely on
numerical models to translate stochastically generated hurricane wind and
pressure forcing into coastal surge and wave estimates. The model output
uncertainty associated with selection of appropriate model parameters must
therefore be addressed. The computational overburden of probabilistic surge
hazard estimates is exacerbated by the high dimensionality of numerical
surge and wave models. We present a model parameter sensitivity analysis of
the Delft3D model for the simulation of hazards posed by Hurricane Bob (1991) utilizing three theoretical wind distributions (NWS23, modified
Rankine, and Holland). The sensitive model parameters (of 11 total
considered) include wind drag, the depth-induced breaking γB,
and the bottom roughness. Several parameters show no sensitivity (threshold
depth, eddy viscosity, wave triad parameters, and depth-induced
breaking αB) and can therefore be excluded to reduce the
computational overburden of probabilistic surge hazard estimates. The
sensitive model parameters also demonstrate a large number of interactions
between parameters and a nonlinear model response. While model outputs
showed sensitivity to several parameters, the ability of these parameters to
act as tuning parameters for calibration is somewhat limited as proper model
calibration is strongly reliant on accurate wind and pressure forcing data.
A comparison of the model performance with forcings from the different wind
models is also presented.
Citation
ID:
227800
Ref Key:
bastidas2016naturalparameter