Changes in the timing of winter-spring streamflows in eastern North America, 1913-2002

Changes in the timing and magnitude of winter-spring streamflows were analyzed for gaging stations in eastern North America north of 41 degrees north latitude during various periods through 2002. Approximately 32 percent of stations north of 44 degrees have significantly earlier flows over the 50, 60, 70, and 90 year periods; 64 percent have significantly earlier flows over the 80 year period; there are no stations significantly later flows for any time period examined. Flows for the average of all stations north of 44 degrees became earlier by 6.1, 4.4, 4.8, 8.6, and 6.5 days for the 50 through 90 year periods, respectively. Changes over time in monthly mean runoff support the flow timing results - January, February, and particularly March runoff show much higher percentages of stations with increases than with decreases over all time periods and May runoff shows relatively high percentages of stations with decreases.