Factors that influence streamflow in the Northeast

Average annual and seasonal runoff and daily mean discharges at selected flow durations of 137 watersheds in the northeast United States totaling less than 100 square miles were related to selected climatic, topographic, and land‐use variables. The most influential variables on annual and seasonal discharges, in descending order, were precipitation, percentage of watershed area in forest cover, elevation, latitude, July mean maximum temperature, and percentage of swamp. Isohyetal precipitation was more highly correlated with average annual runoff than precipitation values from stations closest to the watersheds. The degree of correlation of average annual runoff with average annual precipitation in nonmountainous physiographic units was related to the distance between the precipitation station and the center of the watershed. The proportion of forest cover was correlated positively with runoff, its influence very likely integrating a number of environmental factors that would tend to produce greater runoff.