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Communication at the NABS Annual meeting, Keystone, 2000
(299) INFLUENCE OF WATER TABLE ELEVATION AND REDOX ON SUBSURFACE INPUTS FROM RIPARIAN MEADOWS TO LOW-ORDER STREAMS.
K.A. Dwire, J.B. Kauffman, and J. Brookshire. Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon 97333.
The extent of hydrologic exchange influences subsurface inputs from riparian areas to streams. Our objectives were: (1) to characterize seasonal patterns of water table elevation and oxidation-reduction potential (redox) in two riparian meadows; (2) to estimate subsurface inputs of carbon and nitrogen transported from the meadows to adjacent streams. The study sites border unconstrained reaches of second-order tributaries to the Grande Ronde River, northeast Oregon. Previous hydrologic research revealed that subsurface water movement was generally down-valley and towards the stream. We monitored seasonal water table elevation and redox along wet-to-dry floodplain gradients through three plant communites at each site. We also measured DOC and inorganic nitrogen in stream water and shallow ground water from wells located in the three plant communities. Both water table elevation and redox patterns followed seasonal changes in stream discharge. In streamside wells (wet plant community) concentrations of DOC and inorganic nitrogen were lowest during spring flooding (5.0 mg/l and 0.05 mg/l, respectively), and highest during mid-fall (28 mg/l and 4 mg/l, respectively). Concentrations of DOC and nitrogen were consistently higher in the streamside wells than in the stream, suggesting that this riparian plant community provides subsurface inputs to the stream.
Presented at 2:00 PM on Thursday, June 1, 2000 in Groundwater and Surface Water Interactions I
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