Changes in U.S. Streamflow and Western U.S. Snowpack

Abstract

Hydroclimatological records are increasingly examined for evidence of trends and shifts that may assist in prediction of future climate change scenarios. This study investigates the trend and step changes in U.S. streamflow over a 52-year period (1951–2002) using data from 639 unimpaired streamflow stations categorized according to the hydrologic unit codes. This is particularly relevant since the issue of climate change is of interest to many, and studies have indicated an abrupt change in climate around the year 1976/77. Trends were evaluated using three statistical tests: Spearman’s rho, Mann-Kendall, and linear regression, and step changes were evaluated using the rank sum and student’s