Risk Analysis Method for Computation of Height of Flood Walls

Document Type : Research Article

Authors

Abstract

One of the structural methods for flood control is construction of levees on the banks of rivers. In
traditional design method, the height of floodwall is computed for a fixed design discharge and
uncertainties in design flood determination, river hydraulic conveyance and economic analysis are
ignored whereas in the risk analysis method effects of these uncertainties are included. In this paper,
details of this method were firstly described and then the heights of floodwalls in Qeshlaq River, as a
case study, were calculated by application of the risk analysis method. For this purpose, parameters of
the load function were calculated by fitting statistical distributions on maximum daily flows and
parameters of the wall resistance function were estimated by consideration of uncertainties associated
with Manning coefficient, slope of energy line and geometric characteristics of the sections.
Furthermore, in economical analysis effects of hydraulic and hydrologic uncertainties were
considered. Results showed that application of the traditional method provided underestimated design
values and were less reliable compared with the risk-based design method for the floodwalls of
Qeshlaq River. In conclusion, application of risk analysis method for design of floodwalls was
recommended taking all technical and economical aspects into consideration.