Method for estimating low-flow statistics for ungaged streams in the lower Hudson River Basin, New York

Seven-day, 10-year and 7-day, 2-year low flow statistics were related to selected basin characteristics by multiple-regression analysis for 53 sites with watershed areas of less than 100 sq mi in the lower Hudson River basin. A common 20-year period of record was selected to ensure comparability of results. The most significant variable was the percentage of drainage basin underlain by stratified drift. The lowest standard errors of estimate were obtained from equations giving results in terms of discharge/sq mi during low-flow conditions. The statistically significant basin characteristics needed for estimating low flow were percentage of basin containing stratified drift, mean basin elevation, and mean annual precipitation. The smallest standard errors for 7-day, 10-year and 7-day, 2-year low flows obtained were 51% of the mean and 39% of the mean, respectively. (USGS)