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

Abstract

Changes in the timing and magnitude of winter-spring streamflows were analyzed for gaging stations in eastern North America north of 41° north latitude during various periods through 2002. Approximately 32 percent of stations north of 44° 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° 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.