HR: 1340h
AN: B23A-1038    [Abstracts]
TI: Diurnal Water Table Fluctuations: An Underutilized Indicator of Ground-water Consumption by Plants
AU: * Bauer, J P
EM: Jacob.bauer@colorado.edu
AF: Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047 United States
AU: Shea, J
EM: jsea@gmail.com
AF: Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047 United States
AU: Keller, J
EM: jkeller@siu.edu
AF: Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047 United States
AU: Butler, J J
EM: Jbutler@kgs.ku.edu
AF: Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047 United States
AU: Kluitenberg, G
EM: gjk@ksu.edu
AF: Department of Agronomy, Kansas State University, 2004 Throckmorton Plant Sciences Center, Manhattan, KS 66506 United States
AU: Whittemore, D O
EM: Donwhitt@kgs.ku.edu
AF: Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047 United States
AB: Hydrographs from shallow wells in areas with phreatophytes frequently display a distinctive pattern of diurnal fluctuations. Although first linked to variations in plant water use early in the last century, these diurnal fluctuations have received relatively little attention in the ecohydrology literature. In particular, little attention has been given to exploiting the information embedded in the water-level data to improve understanding of plant water use. Results from two field sites in western Kansas will be presented to demonstrate the insights that can be gleaned from these fluctuations. At one site the vegetation is representative of the native riparian-zone assemblage found over much of the Great Plains (major phreatophyte is the cottonwood [ Populus spp.]), whereas at the other site the vegetation is dominated by invasive species (salt cedar [ Tamarix spp.] and Russian olive [ Elaeagnus angustifoli]). Both sites have a network of shallow wells and neutron probe access tubes for monitoring water-table position and moisture content, respectively. The onset and termination of ground-water use by plants during the growing season is readily identifiable at both sites. Data from the first site show that the maximum depth from which phreatophytes can draw water depends on the previous hydrologic conditions experienced at the site, and not the physiological limits of the plant. Phreatophyte control actions (mulch cutting and chemical treatment) have recently been applied in a sequential fashion to a portion of the second site. The initial impact of those actions on ground-water consumption was not as large as expected, suggesting that forbs and grasses, which were not significantly impacted by these actions, also use substantial amounts of ground water. The magnitude of the diurnal fluctuations ranges appreciably between the sites, and even between wells at the same site. A portion of this difference can be attributed to variations in plant water uptake across a site. Often, however, a more important factor is variation in the specific yield of the sediments in the vicinity of the water table. Thus, the hydrogeology of the shallow subsurface cannot be ignored in interpretations of the fluctuations.
DE: 0483 Riparian systems (0744, 1856)
DE: 1813 Eco-hydrology
DE: 1818 Evapotranspiration
DE: 1852 Plant uptake
SC: Biogeosciences [B]
MN: Fall Meeting 2005