2.3. Flood Mapping Model
One of the important criteria for risk assessment is vulnerability,
which was calculated in SVA by the qualitative approach. This study
tries to make the combination of the vulnerability of assets with the
source of danger, which is a flood due to dam destruction. Thus, it is
necessary to assume different scenarios for the dam break due to
terrorist attacks and obtaining outputs. The outputs of the breaking dam
were used for simulating the flood loaded on downstream lands to obtain
the flood mapping, including the cross-section and velocity of the flood
in the downstream floodplain area. Using HEC-RAS as open-source software
that is compatible with GIS provides advantages to merge data from
security sources with hydraulic and flood data. This software also
allows designing culverts, bridges, side weirs, spillways even if
necessary while the countermeasures are provided.
To model the flow of the flood, the boundary conditions should be
introduced to HEC-RAS software. Boundary conditions (B.C) include
upstream and downstream B.Cs that contain a certain flow rate and water
surface balance, or water surface ramp (angel) and critical depth.
Figure 7 demonstrates the simulation processes of flood mapping in
HEC-RAS software and the transition of outputs to GIS.