Conditional Reliability Modeling of Short-Term River Basin Management

Abstract

A conditional reliability model (CRM) is presented for assessing reliabilities for meeting water needs over the next several months, conditioned upon current reservoir storage contents. The CRM procedure was developed in conjunction with a generalized river/reservoir system model called the Water Rights Analysis Package (WRAP). The CRM methodology is presented in the context of the WRAP model, but the process is applicable to other models as well. A new concept of conditional frequency duration curves, representing probability distributions of naturalized streamflows conditioned on preceding simulated reservoir storage, is incorporated in the CRM methodology. The results of the model are probability-weighted values of storage or diversion from many short-term simulations that start with the same storage condition. Applications of the model in annual operational planning, drought contingency planning, and reservoir resilience analysis are presented, along with pertinent discussions of the fundamental concepts of the model and comparison with the alternative, simpler approach of assuming each short-term simulation is equally likely to occur.