Research

Studies at the WEBB sites have been extensive. Brief examples are given below to illustrate the diversity of the research. Please see individual sites (top bar) and publication lists (side bar) for more information about these and other studies and for bibliographic citiations.

Intersite Comparisons

The climatic, geomorphic, and land-use differences among the WEBB sites provide opportunities for studying differences in hydrologic and biogeochemical responses to climate change, atmospheric chemistry, and disturbance. The following studies have included all five sites:

• a principal-component analysis used to identify the statistical relations between hydrologic conditions and the net exports of major cations, anions, and silica at the five sites. (277 KB, pdf format)
• a mass-balance comparison of water and major-solute fluxes monitored at the five watersheds between 1992 and 1997. (1261 KB, pdf format)
• a comparison of mercury and methylmercury deposition, cycling, and transport in the WEBB watersheds (736 KB, pdf format)

Other Studies

Environmental factors influence the research focus at the sites (e.g., at Loch Vale, Trout Lake, and Sleepers River, the snowmelt pulse is often the dominant hydrologic event of the year, while at Panola and Luquillo, precipitation occurs mainly as rain with tropical storms and hurricanes contributing significantly to annual fluxes of water, solutes, gases, and sediment). The focus of many studies thus is limited to only one or a few WEBB sites or may involve a comparison study of a WEBB watershed with another watershed from a similar setting. (e.g., Sleepers River in Vermont and Hubbard Brook in New Hampshire).

• Because of its montane and alpine environments, limited forest cover, extensive tundra, talus, and rock and snow glaciers, the Loch Vale Watershed is exceptionally sensitive to atmospheric anthropogenic contamination and to climate change. Research at the site has taken advantage of this sensitivity by investigating, for example, the effects of climate on weathering rates, and the effects of nitrogen deposition on the diatom community in the lake. Research at Loch Vale and SNOTEL sites in Colorado, has shown that snowmelt is occurring two weeks earlier than in the late 1970s and runoff timing has shifted by a similar amount; these trends are strongly correlated with warming spring-time temperatures. A warming climate and melting permafrost appear to be affecting groundwater flow and solute fluxes at the site.
• In Luquillo Experimental Forest, the hydrologic, chemical, and sediment processes and budgets in four watersheds of differing geology (granitic versus volcanic) and land use (mature rainforest versus agricultural legacy) have been evaluated. Investigations have included the effects of hurricanes, atmospheric pollution, drought, climate change, precipitation patterns, and land use on hydrology and water quality. Research at the site has looked at the possible causes of amphibian decline and has contributed to an understanding of the dynamics of cloud forest hydrology, detailing the relative importance of orographic and convective precipitation to forested mountain watersheds. Weathering and solute fluxes have been studied and investigations of mass wasting has teased out the importance of several factors affecting landslides, including rainfall intensity and duration, historical land use, and road construction.
• At the Panola Mountain Research Watershed, peak water, carbon, and nitrogen fluxes have been found to occur during tropical storms and hurricanes. Research at the site has investigated the impact of different hydrologic pathways on solute transport and has improved the conceptual understanding of the watershed's response to precipitation over a range of temporal and spatial scales. Studies at the site have looked at biogeochemical cycling, mercury and sulfur dynamics, dry deposition processes and vegetation transpiration effects on soil moisture content. Hillslope studies at the site have quantified the importance of bedrock topography in controlling subsurface stormflow and of bedrock leakage in dominating the hillslope water balance. The watershed also has been compared to urbanized watersheds in the Atlanta area.
• At the Sleepers River Watershed in Vermont, researchers have documented links between variations in snow cover and depth of soil freezing, a finding that may impact flood risk during spring snowmelt. Studies have traced sources and biogeochemical transformations that control the chemical speciation and concentrations of a wide range of stream solutes including nitrogen, carbon, mercury, sulfur, and weathering products. The timing, intensity, and character of organic carbon transport at the site has been studied and contrasted to carbon transport processes in the Yukon River Basin. Acidic deposition effects at the site have also been studied extensively and have been contrasted with those occurring in other watersheds (e.g., with a watershed in the Czech Republic.)
• Because the Trout Lake Watershed ecosystem is dominated by groundwater flow, much of the research at the site has focused on surface water-groundwater interaction. Novel applications of isotope and ion chemistry have been used to investigate lake-groundwater interactions and flow-path processes have been characterized from the unsaturated zone, through the saturated aquifer, to hyporheic discharge locations. Hydrologic modeling tools have been used to better delineate the groundwater watershed, simulate surface-groundwater interactions, and to evaluate the utility of different types of field data for model calibration and prediction. At Trout Lake, the GSFLOW model is being used to propagate climate predictions from IPCC emission scenarios to changes in lake hydrology and ecology.

See individual WEBB sites for additional information, including comparisons with other watersheds. [For articles in Adobe® (.PDF) format, please note that you can download a free copy of Adobe® Acrobat® Reader® here. Also see, Information for users with disabilities, if applicable.]