Paper Reviewed
McCabe, G.J. and Wolock, D.M. 2014. Spatial and temporal patterns in conterminous United States streamflow characteristics. Geophysical Research Letters 41: 6889-6897.

McCabe and Wolock (2014) introduce their paper by writing that "because of concern that global warming might alter the magnitude and timing of streamflow and water supplies, there have been numerous studies of historical patterns in streamflow in the conterminous U.S.," citing the review paper of Peterson et al. (2013) in this regard. And in their own such study, they proceed to examine spatial and temporal patterns in annual and seasonal minimum, mean and maximum daily streamflow values for a set of 516 reference stream gauges located throughout the conterminous United States for the period 1951-2009, during which effort they used cluster analysis to divide the stream gauges into 14 different groups based on the degree of similarity in their temporal patterns of streamflow.

This work revealed that temporal patterns in flow metrics have "strong spatial coherence within each region" and are "similar among the three annual flow metrics [minimum, mean and maximum]," as well as among "the four seasonal flow metrics [December-February, March-May, June-August, and September-November] within each region." They additionally indicate that there do exist "some small magnitude trends over time," but which they say are "only weakly associated with well-known climate indices."

In light of their several findings, McCabe and Wolock conclude that "most of the temporal variability in flow is unpredictable in terms of relations to climate indices," and they thus infer that, "for the most part, future changes in flow characteristics cannot be predicted by these indices." And that is bad news for climate alarmists who continue to insist that CO2-induced global warming is causing (or will cause) more frequent and more severe streamflow trends.

Reference
Peterson, T.C., Heim, R., Hirsch, R., Kaiser, D., Brooks, H., Diffenbaugh, N., Dole, R., Giovannettone, J., Guirguis K, Karl, T., Katz R, Kunke, K., Lettenmaier, D., McCabe, G., Paciorek, C., Ryberg, K., Schubert, S., Silva, V., Stewart, B., Vecchia, A., Villarini, G., Vose, R., Walsh, J., Wehner, M., Wolock, D., Wolter, K., Woodhouse, C. and Wuebbles, D. 2013. Monitoring and understanding changes in heat waves, cold waves, floods, and droughts in the United States: State of knowledge. Bulletin of the American Meteorological Society 94: 821-834.