Coupled Hydrologic & Hydraulic (H&H) models have been widely applied
to simulate both discharge and flood inundation due to their
complementary advantages, yet the H&H models oftentimes suffer from
one-way and weak coupling and particularly disregarded run-on
infiltration or re-infiltration. This could compromise the model
accuracy, such as under-prediction (over-prediction) of subsurface water
contents (surface runoff). In this study, we examine the H&H model
performance differences between the scenarios with and without
re-infiltration process in extreme events¬ – 100-year design rainfall
and 500-year Hurricane Harvey event – from the perspective of flood
depth, inundation extent, and timing. Results from both events underline
that re-infiltration manifests discernable impacts and non-negligible
differences for better predicting flood depth and extents, flood wave
timings, and inundation durations. Saturated hydraulic conductivity and
antecedent soil moisture are found to be the prime contributors to such
differences. For the Hurricane Harvey event, the model performance is
verified against stream gauges and high water marks, from which the
re-infiltration scheme increases the Nash Sutcliffe Efficiency score by
140% on average and reduces maximum depth differences by 17%. This
study highlights that the re-infiltration process should not be
disregarded even in extreme flood simulations. Meanwhile, the new
version of the H&H model – the Coupled Routing and Excess STorage
inundation MApping and Prediction (CREST-iMAP) Version 1.1, which
incorporates such two-way coupling and re-infiltration scheme, is
released for public access.
Dam break analysis and flood inundation mapping using HEC-RAS for piping failure
