When the USGS began work at Sleepers River in 1991, it augmented the traditional hydrologically-based research at Sleepers River with a significant biogeochemical component.  Research has centered on the problem of understanding streamflow generation mechanisms and biogeochemical cycling in low-order catchments.  Well established isotopic, chemical and hydrometric techniques are used, but also less proven multi-isotopic techniques (e.g., combinations of Pb, Sr, and carbon isotopes), which provide complementary information on water source and flow paths.  As the project progressed, riparian processes became the potential key to the stream response.  There seems to be a disconnection between processes on the hillslope and the dynamics of the stream that points to regulation in the riparian areas.  Most of Sleepers River research is done in a headwater forested catchment where hydrologic flow paths are investigated at scales ranging from a linear small hillslope transect (McGlynn and others, 1999) to a larger hillslope (K. Kendall and others., 1999) to the entire 41-ha catchment (Shanley and Kendall, 1992).  The analysis (Smith and others, 1997) was extended to larger nested catchments including the entire Sleepers River Watershed (111 km2), and are actively investigating how streamflow generation mechanisms change as basin size increases and land cover shifts from forested to agricultural fields (Shanley and others, in press).  A National Scientific Foundation grant to McDonnell and others (1999-2002) has enabled focused study of these hillslope - riparian relations.

Scientist sampling for organic carbon fractions at site W-3 in Sleepers River, Watershed, April 2001.

During snowmelt of 2000 and 2001, movement of mercury (Hg) at Sleepers River was monitored. In 2000, 10 different stream sites were sampled that  represent a wide range of catchment size and land cover. Not only were samples analyzed for Hg but for major ions and dissolved organic carbon (DOC) to help understand the factors that control Hg movement. Because Hg behaved similarly at all sites, in 2001 sampling was restricted to just 3 sites, but with increased temporal frequency. The strong Hg-DOC relation found in 2000 was investigated by collecting a subset of samples for organic carbon fractionation and methyl-Hg determination.

The Energy aspects of WEBB have been led by CRREL.   Rae Melloh of CRREL is using radiation and snow water equivalent data to validate SNTHERM,an energy balance model that takes into account internal snowpack processes such as layering and snow grain metamorphism.  We will collaborate with CRREL and use the output of SNTHERM as input to the topographically-based model TOPMODEL to predict stream response to snowmelt.

Sampling of mercury at a agricultural catchment on Sleepers River at site W-2 in Sleepers River Watershed, April 2001.

The WEBB program is committed to continuing several high-quality  historic data sets including (1) streamflow at W-3 (8.3 km2) and W-5 (111  km2) operated continuously since 1959 and providing excellent winter record;  (2) (jointly with CRREL) precipitation, temperature and relative humidity  at 13 sites (hourly since 1959); (3) seasonal snow depth and water equivalent  at 13 sites (weekly since 1959); and (4) seasonal ground frost depth at 5 sites / land use types (weekly since 1983). We operate 5 additional stream  gages (2 reestablished and 3 new), and collect full meteorological data including  radiation at 3 sites, as well as soil moisture, soil temperature, and groundwater  levels.  We collect an average of 1000 samples per year for oxygen-18  and major ion analysis, and a selected subset for less standard determinations  such as 87Sr/86Sr, 13C, and dual isotopes of nitrate.
 

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