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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Flood risk management and adaptation : Appropriate flood risk assessment tools for predicting flood inundation extent and assessing flood h...
Appropriate flood risk assessment tools for predicting flood inundation extent and assessing flood hazard risk for flash flood events
Author : DAVOR KVOČKA (1), ROGER A. FALCONER (2) & MICHAELA BRAY (3)
ABSTRACT
Climate change is predicted to result in more frequent occurrences of extreme flood events, such as flash flooding. This
being the case, there is now an increasing need for accurate flood protection design in the areas susceptible to flash
flooding. However, existing flood risk assessment procedures and methods frequently used, including simplifications of the
computational processes, i.e. a ˇ°simplification strategyˇ±, often do not adequately represent the complex hydrodynamic
processes associated with flash flooding and therefore lead to inadequate flood protection designs. This paper examines
what flood risk assessment tools should be used for flood risk assessment in areas where the emergence of flash flooding
is possible. The 2004 Boscastle flash flood, in the U.K. was selected as a typical case study. Firstly, the appropriateness
of the ˇ°simplification strategyˇ± was investigated, as a flood risk assessment tool for areas prone to flash flooding. Three
different configurations of the DIVAST model were considered in this study, including: (i) with shock-capturing (DIVASTTVD),
(ii) excluding shock-capturing (DIVAST-ADI), and (iii) excluding the inertia terms. The findings reported in this paper
strongly suggest that applying the ˇ°simplification strategyˇ± is not appropriate for areas susceptible to flash flooding. The
results also show that this strategy can lead to significantly erroneous predictions of the main parameters, such as flood
inundation extent. Secondly, two different flood hazard assessment methods were tested, including: (i) a widely used
empirically derived method, and (ii) a new, experimentally derived, and physically based method. The results obtained
suggest that the flood hazard assessment in areas prone to flash flooding should be conducted with physically based
methods, which take into account: (i) all of the physical forces acting on a human body in floodwaters, and (ii) the rapid
changes that often occur in the flow regime, particularly where flash flooding exists.
File Size : 1,699,285 bytes
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Flood risk management and adaptation
Date Published : 28/08/2015
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