Background
One of the major tenets of Climate Alarmism is that global warming will lead to the occurrence of both more floods and more droughts. Hence, it is important to check for trends in river flows that may indicate a growing propensity for such to occur; and that is what Zhang et al. did within the Susquehanna River Basin, which includes parts of Pennsylvania, New York and Maryland, and which is the largest freshwater contributor to North America's Chesapeake Bay, supplying 43% of the bay's drainage area and providing 50% of its water.

What was done
Based on long-term continuous daily streamflow records ending in 2006 for eight unregulated streams with record-lengths ranging from 68 to 93 years that yielded an average length of 82.5 years, the four members of the Susquehanna River Basin Commission used repeated monotonic trend tests with varying beginning and ending times to search for long-term streamflow trends and detect changes in annual minimum, median and maximum daily streamflow.

What was learned
The four researchers report there was "a considerable increase in annual minimum flow for most of the examined watersheds and a noticeable increase in annual median flow for about half of the examined watersheds." However, they found that annual maximum streamflow "does not show significant long-term change."

What it means
Predicting that global warming will lead to more frequent and/or more intense flooding and drought, as climate alarmists do, would seem to almost assure predictive success nearly all the time nearly everywhere. In the case of the Susquehanna River Basin, however, there is no support for this contention, since increases in minimum streamflow suggest a propensity for less severe and/or less frequent drought. And the fact that annual maximum streamflow shows no significant long-term change suggests there has likely been no significant long-term change at the opposite end of the spectrum, where floods might be expected.