HR: 1340h
AN: H43A-0967    [Abstracts]
TI: Recent Trends in USA streamflow: Implications for the Water Cycle
AU: * Krakauer, N Y
EM: niryk@berkeley.edu
AF: Department of Earth and Palnetary Sciences, University of California at Berkeley, 301 McCone Hall, Berkeley, CA 94720,
AU: Fung, I
EM: ifung@berkeley.edu
AF: Department of Earth and Palnetary Sciences, University of California at Berkeley, 301 McCone Hall, Berkeley, CA 94720,
AB: Streamflow provides one of the best indications of changes in the water cycle over land. Most previous analyses of changes in streamflow over decadal timescales have been limited by uncertainty over the impact of land-use change and water diversion and by poor quantification of measurement errors. We mapped annual runoff over the conterminous USA since 1920 based on stream gauge measurements in primarily small, minimally disturbed drainage basins from the (USGS) Hydro-Climatic Data Network (HCDN), using geostatistical methods to estimate the uncertainty in our estimates of areally integrated runoff due to small-scale variability, missing data, and measurement error. We found that runoff generally increased over the period 1940-1990, paralleling increases in precipitation, with a particularly sharp rise in the early 1970s, but has not risen since the early 1990s. Annual runoff shows no significant correlation with local or global temperature over the entire time period. The observed failure of streamflow as well as precipitation over midlatitude land to increase with recent warming speaks against a general "acceleration of the hydrologic cycle" and implies a high risk of reduced water supplies and increased plant water stress with continued warming in coming decades.
DE: 1637 Regional climate change
DE: 1807 Climate impacts
DE: 1860 Streamflow
DE: 1872 Time series analysis (3270, 4277, 4475)
DE: 1880 Water management (6334)
SC: Hydrology [H]
MN: 2007 Fall Meeting