PROGRAM TITLE:	Interaction of Climate and Hydrologic Systems
ACTIVITY STREAMS:	Process, Observations/Data Mgmt., Modeling
SCIENCE ELEMENT:	Climate and Hydrologic Systems

U.S. DEPARTMENT OF THE INTERIOR

DESCRIPTION:  The adequate parameterization of variables representing the 
terrestrial phase of the hydrologic cycle remains a major weakness of existing 
climate models.  The transfer of water and energy to, across, and from the 
land surface is important both as a determinant of climate and as a 
determinant of water availability.  A major emphasis of this program is to 
translate process understanding of hydrologic systems from the plot or basin 
scale up to continental and global scales.

The program encompasses a number of intensive field investigations at 
geographically diverse locations involving both monitoring of and process 
research on the fluxes of water and energy at the land surface, and land-
atmosphere feedback mechanisms.  These field investigations are known as 
the Water, Energy, and Biogeochemical Budgets (WEBB) studies.  They 
involve long-term observation and modeling of the components of water 
and energy budgets to provide information on these interactive processes.

The program objectives are to improve (1) fundamental understanding of the 
response of the hydrologic system to atmospheric conditions and changes, as 
well as the feedback effects on the atmosphere that are produced by the 
hydrologic system; (2) the accuracy of climate model predictions; and (3) the 
accuracy of the predictions of watershed and continental water balance 
response (streamflow, soil moisture, and ground water) to climatic variability 
and change.

STAKEHOLDERS:  The USGS is deeply involved in climate modeling 
activities at NOAA's Geophysical Fluid Dynamics Laboratory and at the 
National Center for Atmospheric Research by having USGS hydrologists 
working as part of the research teams of both institutions on model 
development, testing, and verification.  The USGS WEBB investigations are 
conducted in close collaboration with the Forest Service, National Park 
Service, the U.S. Army Corps of Engineers, and the National Science 
Foundation's Long-Term Ecological Research (LTER) sites.  USGS is also 
playing a pivotal role in the development of the GEWEX project in the 
Mississippi River basin along with NOAA, NASA, and DOE.

SHORT-TERM POLICY PAYOFFS:  In the near term this program will 
provide important guidance to policy makers on where to invest research 
funds to get the most improvement in climate model predictions.  Over the 
longer-term, it will provide the understanding necessary to develop policy-
relevant climate predictions.

PROGRAM CONTACT:	Michael D. Carr
				Global Change Research Coordinator
				U.S. Geological Survey
				104 National Center
				Reston, VA  22092
				Phone (703) 648-4450
				Fax   (703)  648-5470