Streamflow Variability in the United States: 1931–78

Abstract

Systematic modes of spatial and temporal variation in a 48-year record of streamflow are defined using principal components. The components were calculated from a matrix of annual streamflow departures for 106 grid cells covering the United States in the years 1931–78. Five statistically significant components are found to account for more than 56% of the total variance. A varimax orthogonal rotation of the original components describes regional anomaly cores located in the middle Mississippi Valley, Pacific Northwest, Far West, Northeast, and northern Great Plains. Each of these patterns is an enhancement of a less well defined spatial form apparent in the unrotated solution. Temporal variations in the scores of all five components closely agree with contemporaneous national and regional departure patterns in several climatic variables. Abstract Systematic modes of spatial and temporal variation in a 48-year record of streamflow are defined using principal components. The components were calculated from a matrix of annual streamflow departures for 106 grid cells covering the United States in the years 1931–78. Five statistically significant components are found to account for more than 56% of the total variance. A varimax orthogonal rotation of the original components describes regional anomaly cores located in the middle Mississippi Valley, Pacific Northwest, Far West, Northeast, and northern Great Plains. Each of these patterns is an enhancement of a less well defined spatial form apparent in the unrotated solution. Temporal variations in the scores of all five components closely agree with contemporaneous national and regional departure patterns in several climatic variables.