Use of the Critical Period in Reservoir Analysis

Publisher Website
Google Scholar
Abstract
The purpose of this study is to define ‘critical period’ in conjunction with reservoir design and operation and then to analyze the usefulness of the concept in the evaluation of deficiencies of water for project planning purposes. Streamflow records from a number of rivers in the United States are analyzed, and certain defined characteristics of their various critical periods are derived. These characteristics are shown to be functions of both the active storage and the degree of variation in annual streamflow. The dates of occurrence of the critical periods from historical records tend to be stable within certain geographic areas and over a range of active storages. A study is made of the significance of the critical periods and their associated droughts respecting their use for design purposes. This is done by generating large numbers of equally likely hydrographs of the same length as the historical record and comparing the critical periods and yields of these synthetic records with those found in the historical record. Some of the synthetic records produced critical periods in which the severity, measured by the decrease in the full record firm yield, was greater than the historical. However, the generated records as a whole had significantly less severity than the historical records of the same length. The critical periods also showed a strong tendency for nesting, i.e., the larger critical period includes within its duration the smaller critical periods over a wide range of storage and target draft. These observations suggest, but do not prove, that the more severe critical periods observed in historical records may be due to major perturbations of the cause‐effect relationships not reflected by the hypothesis of static probability relationship (i.e., constant parameters).

This publication has 1 reference indexed in Scilit: