HR: 16:00h
AN: H44B-01 INVITED     [Abstracts]
TI: Hydrologic and Biogeochemical Connections between Uplands and Streams in Contrasting Landscapes
AU: * Shanley, J B
EM: jshanley@usgs.gov
AF: U.S. Geological Survey, P.O. Box 628, Montpelier, VT 05601 United States
AU: Webb, R M
EM: rmwebb@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center MS 412, Lakewood, CO 80225 United States
AU: Hjerdt, K N
EM: niclas.hjerdt@eg.umu.se
AF: Ume† University, Uminova Science Park SWEDEN , Ume†, SE-901-87 Sweden
AU: Sebestyen, S D
EM: sdsebest@syr.edu
AF: SUNY-ESF, 1 Forestry Dr., Syracuse, NY 13210 United States
AU: Peters, N E
EM: nepeters@usgs.gov
AF: U.S. Geological Survey, 3039 Amwiler Rd., Atlanta, GA 30360 United States
AU: Burns, D A
EM: daburns@usgs.gov
AF: U.S. Geological Survey, 425 Jordan Rd., Troy, NY 12180 United States
AU: Aulenbach, B T
EM: btaulenb@usgs.gov
AF: U.S. Geological Survey, 3039 Amwiler Rd., Atlanta, GA 30360 United States
AU: Campbell, D H
EM: dhcampbe@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center MS 415, Lakewood, CO 80225 United States
AU: Clow, D W
EM: dwclow@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center MS 415, Lakewood, CO 80225 United States
AU: Mast, M A
EM: mamast@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center MS 415, Lakewood, CO 80225 United States
AU: Walker, J F
EM: jfwalker@usgs.gov
AF: U.S. Geological Survey, 8505 Research Way, Middleton, WI 53562 United States
AU: Hunt, R J
EM: rjhunt@usgs.gov
AF: U.S. Geological Survey, 8505 Research Way, Middleton, WI 53562 United States
AU: Troester, J W
EM: jtroest@usgs.gov
AF: U.S. Geological Survey, 651 Federal Dr., Suite 400-15, Guaynabo, PR 00965 United States
AU: Larsen, M C
EM: mclarsen@usgs.gov
AF: U.S. Geological Survey, 436 National Center 12201 Sunrise Valley Dr., Reston, VA 20192 United States
AB: We used combinations of hydrometric, chemical, and isotopic evidence to evaluate linkages between upland and riparian zones at the 5 small watersheds of the U.S. Geological Survey Water Energy and Biogeochemical Budget (WEBB) program. These sites span a broad range of climate and topography. At Sleepers River, Vermont, snowmelt induced the water table on hillslopes to rise into the highly transmissive upper soil. The close timing of the groundwater and stream hydrographs suggests a large contribution of hillslope water to the stream. However, the chemistry of these upland groundwaters indicates that only limited areas of convergent groundwater flow directly contribute to streamflow. At Panola Mountain, Georgia, a thin saturated zone develops on the hillslope during large rainstorms. This hillslope groundwater is chemically distinct from riparian groundwater, and transits the riparian zone near land surface with little mixing. Based on chemical mixing analysis, the hillslope contributes up to 30% of the streamwater during moderate to large-sized rainstorms. The Trout Lake site in Wisconsin is a low-lying landscape in highly conductive sandy glacial outwash.Hillslope water chemistry is considerably more dilute (i.e. less evolved) than the regional groundwater that supplies baseflow. The lack of chemical response in streamwater during storms suggests that hillslope water makes a minimal contribution relative to regional groundwater flow. In the alpine/subalpine watershed of Loch Vale, Colorado, much of the subsurface flow occurs on steep slopes of talus. Water in the talus flow has a wide range of residence times. The talus deposits are biogeochemically active and play an important role in maintaining summer baseflow, regulating seasonal changes in streamwater chemistry, and exporting nitrogen from atmospheric deposition. The tropical Icacos watershed in the Luquillo mountains of Puerto Rico receives 4 meters of rainfall annually and has high physical and chemical weathering rates. Streamwater chemistry during baseflow is strongly controlled by groundwater interaction with weathered bedrock. Most hillslope runoff occurs through near-surface macropores with limited soil interaction. This source dominates during storms resulting in stream chemistry that resembles that of the extremely dilute precipitation.We will compare these field observations at each site with the aid of TOPMODEL-based simulation of residence times and observed water quality on the hillslope and riparian saturated zones.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting