4. Conclusion
The occurrence of human threats such as military or terrorist attacks on
dams cannot be completely restrained but losses and damages resulted
from it can be reduced. The preliminary and most important step in
reducing the risk of flooding due to the dam’s break is assessing the
risk for the downstream.
By achieving the risk, solutions to reduce the risk of downstream
properties such as early warning or portable flood protection solutions
to deal with this Phenomenon can be assigned for high-risk areas. This
preparation should take place with a specific schedule and planning in
different prospects of crisis management to reduce its damages.
The new hybrid method for vulnerability assessment and risk analysis is
developed in this study by the combination of security risk approaches
and hydraulic of flood due to a dam break. Thus, the basic method for
vulnerability and risk assessment is chosen as SVA, which is approved by
EPA and API. Then for Vulnerability assessment, the HEC-RAS is employed
for achieving velocity and height of flood and flood mapping due to the
different scenarios of the flood. Finally, by using GIS, all elements of
risk are introduced in different layers and by the integration of them,
the risk map is achieved for each scenario. The most important results
are met by applying in a case study as follows:
- Residential areas were considered the most valuable asset according to
the result of the questionnaire using the SVA method.
- The terrorist action became the highest priority among other possible
threats to the earth dam according to the questionnaire using the SVA
method.
- Population centers were considered the highest priority in terms of
consequences based on SVA and SPRC methods.
- The maximum height and speed of the flood are respectively 11/248 m
and 17/63 m/s related to scenario 5 that has been acquired by HEC-RAS
software.
- The minimum arrival time of the flood to population centers is linked
to city 1 for 10 minutes in scenario 5 and the maximum arrival time of
the flood to population centers is linked to city 7 for 205 minutes in
scenario 1.
- Risk modeling illustrates that farmlands achieved the lowest risk and
population centers achieved the greatest risk number due to the
flooding caused by dam break in the most dangerous scenario (scenario
5).