John F Walker (Former Employee)
Science and Products
Filter Total Items: 42
Importance of unsaturated zone flow for simulating recharge in a humid climate Importance of unsaturated zone flow for simulating recharge in a humid climate
Transient recharge to the water table is often not well understood or quantified. Two approaches for simulating transient recharge in a ground water flow model were investigated using the Trout Lake watershed in north-central Wisconsin: (1) a traditional approach of adding recharge directly to the water table and (2) routing the same volume of water through an unsaturated zone column to...
Authors
R. J. Hunt, David E. Prudic, J.F. Walker, Marilyn P. Anderson
Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach
The small watershed approach is well-suited but underutilized in mercury research. We applied the small watershed approach to investigate total mercury (THg) and methylmercury (MeHg) dynamics in streamwater at the five diverse forested headwater catchments of the US Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) program. At all sites, baseflow THg was generally less...
Authors
J. B. Shanley, Mast M. Alisa, K. Campbell, G. R. Aiken, D. P. Krabbenhoft, R. J. Hunt, J.F. Walker, P. F. Schuster, A. Chalmers, Brent T. Aulenbach, N.E. Peters, M. Marvin-DiPasquale, D. W. Clow, M.M. Shafer
Flood of June 2008 in Southern Wisconsin Flood of June 2008 in Southern Wisconsin
In June 2008, heavy rain caused severe flooding across southern Wisconsin. The floods were aggravated by saturated soils that persisted from unusually wet antecedent conditions from a combination of floods in August 2007, more than 100 inches of snow in winter 2007-08, and moist conditions in spring 2008. The flooding caused immediate evacuations and road closures and prolonged...
Authors
Faith A. Fitzpatrick, Marie C. Peppler, John F. Walker, William J. Rose, Robert J. Waschbusch, James L. Kennedy
Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor
Discrete zones of groundwater discharge in a stream within a peat‐dominated wetland were identified on the basis of variations in streambed temperature using a distributed temperature sensor (DTS). The DTS gives measurements of the spatial (±1 m) and temporal (15 min) variation of streambed temperature over a much larger reach of stream (>800 m) than previous methods. Isolated...
Authors
Christopher S. Lowry, John F. Walker, Randall J. Hunt, Mary P. Anderson
Dynamics of CFCs in northern temperate lakes and adjacent groundwater Dynamics of CFCs in northern temperate lakes and adjacent groundwater
Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding...
Authors
John F. Walker, David A. Saad, Randall J. Hunt
Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S. Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S.
Geochemical mass balances were computed for water years 1992-1997 (October 1991 through September 1997) for the five watersheds of the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) Program to determine the primary regional controls on yields of the major dissolved inorganic solutes. The sites, which vary markedly with respect to climate, geology, physiography...
Authors
N.E. Peters, J. B. Shanley, Brent T. Aulenbach, R. M. Webb, K. Campbell, R. Hunt, M. C. Larsen, R.F. Stallard, J. Troester, J.F. Walker
Science and Products
Filter Total Items: 42
Importance of unsaturated zone flow for simulating recharge in a humid climate Importance of unsaturated zone flow for simulating recharge in a humid climate
Transient recharge to the water table is often not well understood or quantified. Two approaches for simulating transient recharge in a ground water flow model were investigated using the Trout Lake watershed in north-central Wisconsin: (1) a traditional approach of adding recharge directly to the water table and (2) routing the same volume of water through an unsaturated zone column to...
Authors
R. J. Hunt, David E. Prudic, J.F. Walker, Marilyn P. Anderson
Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach
The small watershed approach is well-suited but underutilized in mercury research. We applied the small watershed approach to investigate total mercury (THg) and methylmercury (MeHg) dynamics in streamwater at the five diverse forested headwater catchments of the US Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) program. At all sites, baseflow THg was generally less...
Authors
J. B. Shanley, Mast M. Alisa, K. Campbell, G. R. Aiken, D. P. Krabbenhoft, R. J. Hunt, J.F. Walker, P. F. Schuster, A. Chalmers, Brent T. Aulenbach, N.E. Peters, M. Marvin-DiPasquale, D. W. Clow, M.M. Shafer
Flood of June 2008 in Southern Wisconsin Flood of June 2008 in Southern Wisconsin
In June 2008, heavy rain caused severe flooding across southern Wisconsin. The floods were aggravated by saturated soils that persisted from unusually wet antecedent conditions from a combination of floods in August 2007, more than 100 inches of snow in winter 2007-08, and moist conditions in spring 2008. The flooding caused immediate evacuations and road closures and prolonged...
Authors
Faith A. Fitzpatrick, Marie C. Peppler, John F. Walker, William J. Rose, Robert J. Waschbusch, James L. Kennedy
Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor
Discrete zones of groundwater discharge in a stream within a peat‐dominated wetland were identified on the basis of variations in streambed temperature using a distributed temperature sensor (DTS). The DTS gives measurements of the spatial (±1 m) and temporal (15 min) variation of streambed temperature over a much larger reach of stream (>800 m) than previous methods. Isolated...
Authors
Christopher S. Lowry, John F. Walker, Randall J. Hunt, Mary P. Anderson
Dynamics of CFCs in northern temperate lakes and adjacent groundwater Dynamics of CFCs in northern temperate lakes and adjacent groundwater
Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding...
Authors
John F. Walker, David A. Saad, Randall J. Hunt
Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S. Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S.
Geochemical mass balances were computed for water years 1992-1997 (October 1991 through September 1997) for the five watersheds of the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) Program to determine the primary regional controls on yields of the major dissolved inorganic solutes. The sites, which vary markedly with respect to climate, geology, physiography...
Authors
N.E. Peters, J. B. Shanley, Brent T. Aulenbach, R. M. Webb, K. Campbell, R. Hunt, M. C. Larsen, R.F. Stallard, J. Troester, J.F. Walker