First-order reliability method for estimating reliability, vulnerability, and resilience

Reliability, vulnerability, and resilience provide measures of the frequenc y, magnitude, and duration of the failure of water resources systems, respe ctively. Traditionally, these measures have been estimated using simulation . However, this can be computationally intensive, particularly when complex system-response models are used, when many estimates of the performance me asures are required, and when persistence among the data needs to be taken into account. In this paper, an efficient method for estimating reliability , vulnerability, and resilience, which; is based on the First-Order Reliabi lity Method (FORM), is developed and demonstrated for the case study of man aging water quality in the Willamette River, Oregon. Reliability, vulnerabi lity, and resilience are determined for different dissolved oxygen (DP) sta ndards. DO is simulated using a QUAL2EU water quality response model that h as recently been developed for the Oregon Department of Environmental Quali ty (ODEQ) as part of the Willamette River Basin Water Quality Study (WRBWQS ). The results obtained indicate that FORM can be used to efficiently estim ate reliability, vulnerability, and resilience.