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United States Department of Agriculture

Agricultural Research Service

Title: Linkages among Groundwater Levels, Evapotranspiration Rates, and Stream Flows Within a First-Order Riparian Zone, and the Impact of Climate Variability

item Angier, Jonathan
item McCarty, Gregory

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2003
Publication Date: March 20, 2003
Citation: Angier, J., McCarty, G.W. 2003. Linkages among groundwater levels, evapotranspiration rates, and stream flows within a first-order riparian zone, and the impact of climate variability [abstract]. American Geophysical Union. Paper No. 5797. 2003 CDROM.

Technical Abstract: Complex interactions among different aspects of a riparian system largely determine how efficiently these environments function at such things as contaminant removal and flood attenuation. Many studies focus on only one or two aspects of a riparian system and make assumptions regarding other elements of riparian system behavior. Conclusions that predict function based on a small number of factors, however, are more likely to be inaccurate and are probably less applicable to other systems. An approach to riparian zone studies that attempts to address several major influences on the system¿s behavior is more likely to yield information that can be applied to predictive models. This study, part of a small-watershed project undertaken by the USDA-ARS, is an attempt to apply a holistic approach to assessing riparian zone function. Stream flows are measured and logged automatically at five points along the stream channel. Approximately 170 piezometers are used to assess groundwater behavior and composition within the riparian system; about 60 of these are instrumented with pressure transducers that continuously log groundwater levels. Twelve sap flow sensors have been placed into five tree trunks in a transect across the riparian zone to measure sap flow rates (and ultimately to obtain evapotranspiration rates for the riparian zone). Meteorological data is obtained from an on-site weather station. The data indicate that there is a close linkage between stream flow and tree sap flow. Diurnal sap flow patterns (active sap flow in daytime during the growing season) are reflected in loss of daytime stream flow. Sap flow rates in turn are highly influenced by changes in local weather conditions (especially photosynthetically active radiation). Stream flow and climate are also directly linked to groundwater behavior. Information gleaned from this study (which also includes research incorporating local hydrology and biogeochemistry) can be used to help determine how these various elements of a riparian system interact and the effect on the function of the system as whole.

Last Modified: 4/20/2015
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