Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

WRMD has defined a preference for hydrologic and hydraulic modeling using HEC-HMS
and HEC-RAS.
HEC-GeoRAS, first released in 1999, is a set of procedures, tools, and utilities for
processing geospatial data in ArcGIS using a graphical user interface. The interface
allows the preparation of geometric data for import into HEC-RAS and processes
simulation results exported from HEC-RAS. This now mature (vs. 4.2) tool offers, among
numerous other capabilities, the ability to optimize the positioning of cross-sections for
input into RAS and also to rapidly generate scenario flood inundation surface outputs for
QA/QC and to visualize these spatially together with input hydraulic parameters and
ancillary data such as topography and aerial photos. Both approaches offer the potential
to improve model performance and the reliability of resulting floodplain mapping.
The existing flood studies detail the name of the software which was used for hydrologic and
hydraulic modeling but not the version of the HEC code used. However, by using the HEC
release dates in conjunction with the reporting dates of the flood studies, an expectation of
which version of software was used can be established.
For the prioritization effort, a weighting of “1” will be given to existing flood studies where the
hydraulic model is outdated or no longer supported (i.e., pre-dating May 2003). Where the
hydraulic modeling is based on HEC-RAS 3.1.1 or later, a weighting of “0” will be assigned. All
of the presently available flood studies pre-date 2000 (except studies currently underway
including Corner Brook Stream, Petrie‟s Brook and Petty Harbour River and the study
completed for Stephenville in 2009).
4.1.5 Climate Change
Newfoundland and Labrador is expected to experience changes in temperature, precipitation,
sea level and other factors in the future as a result of climate change. These factors can
influence the flood risk faced by a community directly or indirectly. Climate change may result in
communities which are not presently at risk of flooding being included in the list of potential
candidates for new flood plain mapping.
The potential impacts of climate change on flood risk were assessed as a component C4 –
Assess Climate Change Impacts, of this project with the following general outcomes for each of
the four WRMD regions as indicated below in Table 4-2.
TA1112733 page 97