Evaluating Estimates of Channel Flow in a Continental-Scale Lake-Dominated Basin

Abstract

Accurate estimates of continental-scale channel flows are needed to understand spatiotemporal variability in water supplies and the water balance. At regional scales, models of connecting channel flows are commonly used to understand how variability in the water cycle propagates into engineering-oriented decisions related to water quantity and water quality management. Since 1958, deterministic monthly flows have been calculated for all of the connecting channels of the Great Lakes–St. Lawrence River system through a binational, multiagency coordination process. This article provides a review of these historical estimates, most of which have never appeared (or appeared decades ago) in the peer-reviewed literature, and compares them to new estimates from a novel statistical water balance model. This new model was developed using a variety of water balance component estimates across the entire Great Lakes system and includes an explicit expression of uncertainty. The findings of this research indicate that the historical range of deterministic channel flow estimates is similar to the range of uncertainty represented by the authors’ statistical water balance model. Findings also indicate that historical internationally coordinated flows for this massive lake and river system from the late 1990s through 2009 appear to be negatively biased and may need to be revised. The proposed statistical water balance model provides an ideal platform for implementing this revision and other future updates to regional water balance information.