National Research Program
Water and Solute Mass Balance
Scientists use watershed mass balance calculations to estimate the changes that occur when water interacts with a watershed's vegetation, soils, and bedrock. A comparison of the mass of water and accompanying dissolved and suspended materials that is entering a watershed with what exits that watershed enables them to better understand weathering and other abiotic and biotic reactions and provides them with a means to better understand human influence on water quality.
Taking this approach a step further, USGS scientists used mass balance calculations to compare the differences and similarities of five small, relatively undisturbed watersheds that have greatly differing climate, geology, physiography, and ecology. Data were collected over a six-year period (October 1991 through September 1997) in a study of the five watersheds of the USGS Water, Energy, and Biogeochemical (WEBB) program. In evaluating the monthly and annual watershed mass balance of water and major inorganic solutes in the five watersheds (located in Colorado, Wisconsin, Vermont, Georgia, and Puerto Rico), the variety of conditions (alpine/subalpine, boreal, temperate, subtropical, tropical) provided a gradient in which to study and contrast processes within and across watersheds, and to determine the primary regional controls on yields of the major dissolved inorganic solutes.
Results reported in a 2006 journal article included the following:
Peters N.E., Shanley, J.B., Aulenbach, B.T., Webb, R.M., Campbell, D.H., Hunt, R., Larsen, M.C., Stallard, R.F., Troester, J., and Walker, J.F., 2006, Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S.: Science of the Total Environment, v. 358, p. 221- 242.
Also see the Water, Energy, and Biogeochemical Budgets (WEBB) program home page for related research or contact Earl Greene, email@example.com.