Water, Energy, and Biogeochemical Budgets

U.S. Department of the Interior 

U.S. Geological Survey

Fact Sheet-165-99

June 2000

A Watershed Research Program

disturbances, and non-point source pollution. Efforts at the sites include installation 

of instrumentation and collection of longterm data for key environmental variables 

and fluxes. The first phase of the WEBB 

Program focused on understanding processes at the individual watersheds.

The next phase of 

research will compare and contrast 

process understanding in these small 

watersheds and 

describe processes in 

larger watersheds so 

that water, energy, 

and biogeochemical 

budgets can be predicted over a wide 

range of spatial and 

temporal scales. The 

three areas that have 

been identified for increased research 

efforts are: (1) to understand the effect 

of the geologic and physiographic framework, land use, landscape characteristics, and climatic setting of a watershed 

on the generation of streamflow or fluctuations of lake levels by using appropriate modeling techniques, (2) to increase 

our understanding of temporal and climatic factors that affect solute input, 

export, and retention, and (3) to estimate 

the impacts of land-use change on erosion and water/soil resource degradation 

by developing sediment budgets and comparing carbon inventories and fluxes. 

Challenges for the coming decade in 

small watershed investigations will be 

to improve understanding of the effect 

of human influences on natural systems 

and to provide information for the restoration of damaged watersheds.

Watershed Sites in 

the WEBB Program

Loch Vale Watershed in Colorado is an 

alpine/subalpine watershed that is typical of ecosystems in the Rocky Mountains. Lying within Rocky Mountain 

National Park and administered by the 

National Park Service, the watershed 

has been part of the interagency 

National Acid Precipitation Assessment 

Program (NAPAP) and is a United 

Nations Educational, Scientific, and Cultural Organization (UNESCO) designated International Biosphere Reserve.

The U.S. Geological Survey (USGS) initiated the Water, Energy, and Biogeochemical Budgets (WEBB) program in 1991 to investigate processes, 

including the effect of atmospheric and climatic variables, that control 

water, energy, and biogeochemical fluxes over a range of temporal and 

spatial scales (Lins, 1994). Five research field sites were selected: Loch 

Vale Watershed, Luquillo Experimental Forest, Panola Mountain Watershed, 

Sleepers River Watershed, and Trout Lake Watershed. Site selection was 

based in part on the existence of long-term data sets on which the WEBB 

program could build, and in part to be geographically and ecologically 

diverse and represent a range of hydrologic and climatic conditions.

Watershed research provides 

vital understanding needed to 

guide decisions related to 

water resources and environmental quality. The USGS investigates watersheds 

at several scales that include the largest 

river-basins in the 

nation with data gathered through the 

National Stream 

Quality Accounting 

Network (NASQAN), 

mid-sized watersheds 

like the Potomac 

River Basin or Sacramento River Basin 

in the National Water 

Quality Assessment 

Program (NAWQA), 

and small watersheds 

like those in the 

Hydrologic Benchmark Network (HBN) 

Program, and the 

Watershed Ecosystem Studies Program 

and the WEBB Program (see map on last 

page). Information and results are shared 

within and between these programs.

In the WEBB Program, long-term field 

studies are used to explore temporal and 

spatial scaling issues. They provide a 

basis for determining decadal-scale trends 

in water and environmental quality that are 

related to atmospheric deposition, regional 

and global climate variations, changes in 

atmospheric composition, anthropogenic 

The network of lakes in the Trout Lake 

Watershed, Wisconsin, are interconnected 

by ground water. Four of the seven lakes in 

the study area are seepage lakes, with no 

surface-water inlets or outlets.

Water cascades down a tributary of the 

Mameyes River, Puerto Rico. Runoff in the 

WEBB watersheds in the Luquillo Mountains averaged from 49 to 82 percent of 

precipitation inputs during the 1990s.
Luquillo Experimental Forest in eastern Puerto Rico is a tropical rainforest. 

It is administered by the U.S. Forest Service and is supported by the National Science Foundation (NSF) as a Long-Term 

Ecological Research (LTER) site and 

is an UNESCO-designated International 

Biosphere Reserve. WEBB research is 

also conducted in the nearby Río Grande 

de Loíza drainage basin, an urban and 

agriculturally developed watershed.

Panola Mountain Watershed in Georgia is a forested watershed previously 

under cultivation which is located southeast of Atlanta in the Georgia Piedmont. 

It is in the Georgia Department of Natural 

Resources Panola Mountain State Conservation Park, and has been part of NAPAP.

Sleepers River Watershed in northeastern Vermont is mostly hardwood 

forest with the remaining land primarily 

pasture for dairy farming. Research 

in the watershed was begun by the 

Department of Agriculture’s Agricultural 

Research Service in 1959 and now is 

conducted jointly by the USGS and the 

U.S. Army Cold Regions Research and 

Engineering Laboratory (CRREL). The 

site also has been used as a comparison 

site to the Hubbard Brook LTER site.

Trout Lake Watershed in north-central Wisconsin is in a forested upland 

area that is characterized by a moderately dense distribution of lakes, which is 

typical of the low-relief, glaciated terrain 

occurring over much of the upper Midwest and southern Canada. The watershed is supported by NSF as the North 

Temperate Lakes LTER, which is operated through the University of Wisconsin’s Center for Limnology.

Major Research Topics

The WEBB watersheds have different 

physiographic settings, hydrologic processes, atmospheric inputs, and weathering reactions. The focus of research in 

the individual watersheds reflects these 

differences. Major research efforts include:

Flowpath Studies

Research efforts focus on identifying 

and delineating the sources and flowpaths of ground water and surface water 

and on studying their interactions. TOPMODEL, which is a computer model 

based on surface topography, has been 

used to help understand water flow at 

Sleepers River (Wolock, 1995) and at 

Panola Mountain where bedrock topography was found to also be important 

(Freer and others, 1997). The knowledge 

of how water moves through the system 

provides a framework for investigating 

the biological and geochemical influences on water chemistry. In the Trout 

Lake watershed, for example, deuterium, 

oxygen-18, and strontium isotopes have 

been used to differentiate ground water 

recharged by lake seepage from ground 

water that has been recharged by precipitation that infiltrates the inter-lake 

uplands (Bullen and others, 1996). It 

also was determined that dissolved 

organic carbon, carbon dioxide, and 

methane are generated as ground water 

flows through the hyporheic zone and 

discharges into a stream in the watershed 

(Schindler and Krabbenhoft, 1998).

Climatic Gradients

The five WEBB sites represent watersheds along a continuum of annual 

precipitation and temperature—from 

Luquillo in the tropics, where conditions 

are warm and wet, to the alpine Loch 

Vale site in Colorado. The variety of 

conditions (tropical, subtropical, temperate, subalpine, alpine) provide a gradient 

in which to study and contrast processes, 

such as weathering and sediment transport, within and across watersheds. For 

example, three independently collected 

sets of data from the Luquillo watershed 

in Puerto Rico indicate that possible 

changes in precipitation, temperature, 

and vegetation during the past several 

hundred thousand years have not significantly impacted the weathering rates of 

silicate rocks. Furthermore, the rate was 

found to be an order of magnitude faster 

than the global average (White and others, 1998).

Mass Budgets

A mass balance approach is being used 

to characterize and understand the processes that control the distribution and 

transport of sediment and solutes in and 

through the watersheds. This approach 

is helping scientists and managers understand landscape-scale processing of (1) 

solutes from weathering, (2) pollutants 

that are components of atmospheric 

deposition, and (3) sediment from erosion and landscape disturbance. Measurements of inorganic nitrogen fluxes made 

at Loch Vale, Colorado, for example, 

showed that the annual export of nitrogen from the watershed is not directly 

related to atmospheric deposition and 

suggests that biogeochemical cycling 

controls the release of nitrogen even 

in areas where soil and vegetation are 

sparse (Campbell and others, 2000). 

Environmental Change

Research investigations have been used 

to reconstruct background environmental 

At Sleepers River, Vermont, nearly half of 

the annual streamflow occurs in the six 

weeks of spring snowmelt.

Loch Vale Watershed in 

Colorado, is an alpine/

subalpine watershed that 

is typical of ecosystems 

in the Rocky Mountains. 

Melting of the snowpack 

is a major hydrologic 

event each year.
—Mary Jo Baedecker and 

Linda C. Friedman

Information about the WEBB program is available on the internet:

http://water.usgs.gov/nrp/webb/

REFERENCES

Baron, J.S., and Williams, M.W., 2000, Preface (to 

special section: recent Loch Vale watershed research): 

Water Resources Research, v. 36, no. 1, p. 11–12.

Bullen, T.D., Krabbenhoft, D.P., and Kendall, C., 

1996, Kinetic and mineralogic controls on the evolution of groundwater chemistry and 87Sr/86Sr in a 

sandy silicate aquifer, northern Wisconsin, USA: Geochimica et Cosmochimica Acta, v. 60, no. 10, p. 

1807–1821.

Campbell, D.H., Baron, J.S., Tonnessen, K.A., Brooks, 

P.D., and Schuster, P.F., 2000, Controls on nitrogen 

flux in alpine/subalpine watersheds of Colorado: 

Water Resources Research, v. 36, no. 1, p. 37–47.

Freer, J., McDonnell, J.J., Beven, K.H., Brammer, D., 

Burns, D.A., Hooper, R.P., and Kendall, C., 1997, 

Topographic controls on subsurface storm flow at 

the hillslope scale for two hydrologically distinct 

small catchments: Hydrological Processes, v. 11, p. 

1347–1352.

Larsen, M.C., and Torres Sánchez, A.J., 1998, The 

frequency and distribution of recent landslides in three 

montane tropical regions of Puerto Rico: Geomorphology, v. 24, no. 4, p. 309–331.

Lins, H.F., 1994, Recent directions taken in Water, 

Energy, and Biogeochemical Budgets research: EOS, 

v. 75, n. 43, p. 438–439.

Schindler, J.E., and Krabbenhoft, D.P., 1998, The 

hyporheic zone as a source of dissolved organic carbon and carbon gases to a temperate forested stream: 

Biogeochemistry, v. 43, p. 157–174.

conditions. For example, data from the 

WEBB program, the Hydrologic Benchmark Network, and other relatively 

undisturbed watersheds are being used 

to establish a background level for nutrient fluxes. The data will provide a 

reference for comparisons of nutrient 

fluxes from urban and agricultural watersheds. Understanding background conditions and natural variability allows 

early warning of environmental change 

and comparisons between near pristine 

and human-impacted watersheds. Such 

a comparison is being made in Puerto 

Rico. Resulting data indicate that landslides are most likely to occur on 

hillslopes that were anthropogenically 

modified, face the east-northeast, and 

exceed 12 degrees in gradient and 350 

meters in elevation, whereas bedrock 

geology and soil order seem less important in the determination of landslide 

frequency (Larsen and Torres-Sánchez, 

1998).

Collaborative Research

Studies at the WEBB sites have benefited from the infrastructure and longterm data support provided by other 

agencies, as noted in the descriptions of 

the five sites, and from a strong collaborative research relationship with scientists 

from other Federal and State agencies 

and from over twenty universities. 

Students and volunteers have helped 

collect, process, and archive data and 

samples, and university faculty and graduate students have helped to advance 

our scientific understanding of important 

biogeochemical and hydrological processes and budgets by conducting 

research and publishing their results. 

Since the beginning of the program in 

1991, 50 students have completed their 

theses or dissertations from work as a 

result of interactions with WEBB investigators and an equal number of university faculty advisors have collaborated 

with USGS scientists. The collaborative 

research efforts at the sites are exemplified by a compilation of seven papers on 

Loch Vale that were written by 20 investigators from eight institutions and were 

recently published in Water Resources 

Research (Baron and Williams, 2000). 

Cooperative efforts will continue to be 

fostered at all five sites and collaborations with scientists from other agencies 

and universities to enhance understanding of watershed systems will continue 

White, A.F., Blum, A.E., Schulz, M.S., Vivit, D.V., 

Stonestrom, D.A., Larsen, M., Murphy, S.F., and 

Eberl, D., 1998, Chemical weathering in a tropical 

watershed, Luquillo Mountains, Puerto Rico: I. Longterm versus short-term fluxes: Geochimica et Cosmochimica Acta, v. 62, no. 2. p. 209–226. 

Wolock, D.M., 1995, Effects of subbasin size on topographic characteristics and simulated flow paths in 

Sleepers River watershed, Vermont: Water Resources 

Research, v. 31, p. 1989–1997.

Individual fact sheets describe 

in detail the research being 

done in each watershed:

• Walker, J.F., and Bullen, T.D., 

2000, Trout Lake, Wisconsin—A Water, Energy, and Biogeochemical Budgets Program 

Site: U.S. Geological Survey 

Fact Sheet-161-99.

• Peters, N.E., Hooper, R.P., Huntington, T.G., and Aulenbach, 

B.T., 2000, Panola Mountain, 

Georgia—A Water, Energy, 

and Biogeochemical Budgets 

Program Site: U.S. Geological 

Survey Fact Sheet-162-99.

• Larsen, M.C., and Stallard, 

R.F., 2000, Luquillo Mountains, 

Puerto Rico—A Water, Energy, 

and Biogeochemical Budgets 

Program Site: U.S. Geological 

Survey Fact Sheet-163-99.

• Clow, D.W., Campbell, D.H., 

Mast, M.A, Striegl, R.G., Wickland, K.P., and Ingersoll, G.P., 

2000, Loch Vale, Colorado—A 

Water, Energy, and Biogeochemical Budgets Program 

Site: U.S. Geological Survey 

Fact Sheet-164-99.

• Shanley, J.B., 2000, Sleepers 

River, Vermont—A Water, Energy, and Biogeochemical 

Budgets Program Site: U.S. 

Geological Survey Fact Sheet166-99. 

The Panola Mountain 

Watershed in Georgia 

is 93 percent forested. 

The remaining 7 percent is rock outcrop, as 

shown here, covered 

with lichen and moss 

with islands of shrubs 

and trees.
 WEBB Research Sites

Loch Vale, Colorado

Panola Mountain, Georgia

Luquillo Experimental Forest, Puerto Rico

Sleepers River, Vermont

Trout Lake, Wisconsin

Other Small Watershed Research Sites

Noatak National Preserve, Alaska*

Denali National Park, Alaska* 

Sequoia and Kings Canyon National Parks, California*

Rocky Mountain National Park, Colorado*

Catoctin Mountains, Maryland

Isle Royale National Park and Lake Superior Basin, Michigan*

Shingobee Headwaters Research Area, Minnesota

Glacier National Park, Montana*

Crescent Lake, Nebraska

Mirror Lake, New Hampshire

Rio Puerco Basin, New Mexico

Nerversink, New York

Cottonwood Lake, North Dakota

Great Smoky Mountains National Park, North Carolina and Tennessee*

Massanutten, Virginia

Old Ridge Mountains, Virginia

Shenandoah National Park, Virginia

Big Bend National Park, Texas*

Olympic National Park, Washington*

*part of the Watershed Ecosystems Studies Program

National Stream Quality Accounting Network (NASQAN) stations

Designed to monitor water quality of the Nation’s largest rivers.

Hydrologic Benchmark Network (HBN) Sites

Designed to monitor water quality of selected underdeveloped watersheds. HBN 

 stations are being operated on a rotational basis.

National Water Quality Assessment (NAWQA) Program study units

Designed to describe how the quality of the Nation’s water resources changes 

with time and with natural and human influences.

For additional information about the WEBB 

Program, contact

Assistant Chief Hydrologist for Research

US Geological Survey

12201 Sunrise Valley Drive, MS 436

Reston, VA 20192

Puerto Rico

USGS Long-Term Watershed Research Sites