Modelling Uncertainty in Flood Studies

Estimates of average annual damage (AAD) are a key central component of the hydrologic, hydraulic, and economic information developed in the evaluation of flood damage reduction plans. AAD or the expected value of annual damage, in dollars or other monetary units, is a probability-weighted average of the economic losses associated with the full range of possible flood magnitudes. Economic benefits are assessed as the reduction in AAD which would result from implementation of a particular plan. Traditional methodologies for performing hydrologic, hydraulic, and economic studies and estimating AAD have recently been expanded to explicitly incorporate analysis of the uncertainties inherent in the data collection and modelling effort. This paper presents a strategy for modelling uncertainties in the estimation of AAD for ungauged urban floodplains.