by Butler, J.J., Jr., Kluitenberg, G.J., Whittemore, D.O., Healey, J.M., and Zhan, X.
Eos Trans. AGU, v. 86, no. 18, Jt. Assem. Suppl., Abstract H33B-06, 2005.
Consumption of ground water by phreatophytes in riparian corridors is thought to be one factor responsible for stream-flow reductions in western Kansas and elsewhere. Extensive phreatophyte-control measures, primarily focusing on invasive species such as salt cedar and Russian olive, are being considered in response to concerns about the impact of phreatophytes on surface-and ground-water resources. At present, there is no generally accepted means of quantifying the ground-water savings that might be gained through these control measures. Micrometeorological methods are often not appropriate for this application because their fetch requirements are too large for narrow riparian corridors. Recently, an approach based on diurnal fluctuations in the water table has been shown to have potential for quantifying ground-water consumption by phreatophytes. A demonstration project is underway to examine the utility of this method for assessing ground-water savings achieved through phreatophyte-control measures. This project is being carried out at a research site in a region of salt-cedar infestation along the Cimarron River in southwestern Kansas. The site has been subdivided into four areas of approximately four hectares each in which different salt-cedar control measures will be applied. Control measures will not be used in one area so that data unaffected by those measures can be obtained throughout the project. Wells equipped with submersible pressure sensors have been installed to monitor water-table responses in the vicinity of the most common phreatophyte communities at the site. A neutron access tube has been emplaced adjacent to each well so that water content in the vadose zone can also be monitored. Changes in water-content profiles will be used to estimate specific yield, a critical parameter in the proposed methodology. A weather station has also been installed on site to monitor meteorological conditions and provide reference ET estimates. Water-level data collected prior to any control activities clearly indicate that the magnitude of the water-table fluctuations is highly dependent on the apparent vitality of the phreatophyte community in the vicinity of each well. After the control measures have been applied, water-level data from the treated areas will be compared to data from the untreated area. That comparison should enable quantification of reductions in ground-water consumption produced by those measures.
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Kansas Geological Survey and Kansas State University,
Phreatophyte Research Project
Updated Nov. 17, 2005
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