Uncertainty analysis and risk-based design of detention basin without damage function

Abstract

Risk-based analysis provides an economically defensible framework for determining the optimal design of hydrosystems with the minimum total cost including project cost (installation plus operation/maintenance/repair) and failure-induced expected damage cost. However, failure-related damage function with good quality may not be widely available in practical applications for assessing annual expected damage cost. In addition to aleatory uncertainty representing natural randomness of hydrologic events, there exists a variety of epistemic uncertainties due to knowledge deficiency from the use of inadequate models, inaccurate model parameters, etc. The presence of epistemic uncertainties could affect the loads and capacity of hydrosystem facilities which, in turn, would affect the value of failure-induced physical performance indicators. Using detention basin design as an example, this paper presents a systematic framework to integrate aleatory and epistemic uncertainties for the risk-based design under the condition of no monetary damage function. For illustration, aleatory uncertainty due to randomness of rainfall intensity and epistemic uncertainties caused by runoff coefficient and curve number are considered in risk-based design of an example detention basin. Plain Language Summary Due to the presence of uncertainties from natural randomness of hydrologic events and knowledge deficiency, risk-based procedure provides a economically and logically defensible framework for determining the optimal design of hydrosystems with the minimum total cost including project cost and failure induced damage cost. However, such framework requires failure related damage information with good quality, which may not be widely available in practical applications. To extend the generality and usefulness the risk-based procedure, this paper presents a viable framework to integrate aleatory and epistemic uncertainties in risk-based design under the condition of without monetary damage information. Design of stormwater detention basin is used as an example to illustrate the methodology.