Richard Webb (Former Employee)
Science and Products
Filter Total Items: 37
Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico
Coral reefs, the foundation and primary structure of many highly productive and diverse tropical marine ecosystems, have been degraded by human activity in much of the earth's tropical oceans. To contribute to improved understanding of this problem, the potential relation between river sediment and nutrient discharges and degradation of coral reefs surrounding Puerto Rico was studied...
Authors
M. Larsen, R.M.T. Webb
Using a coupled groundwater/surface-water model to predict climate-change impacts to lakes in the Trout Lake Watershed, northern Wisconsin Using a coupled groundwater/surface-water model to predict climate-change impacts to lakes in the Trout Lake Watershed, northern Wisconsin
A major focus of the U.S. Geological Survey’s Trout Lake Water, Energy, and Biogeochemical Budgets (WEBB) project is the development of a watershed model to allow predictions of hydrologic response to future conditions including land-use and climate change. The coupled groundwater/surface-water model GSFLOW was chosen for this purpose because it could easily incorporate an existing...
Authors
Randall J. Hunt, John Walker, Steven L. Markstrom, Lauren Hay, John Doherty
Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA
Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected...
Authors
T.C. Hancock, Mark Sandstrom, J. Vogel, R.M.T. Webb, E.R. Bayless, J.E. Barbash
Simulated fate and transport of metolachlor in the unsaturated zone, Maryland, USA Simulated fate and transport of metolachlor in the unsaturated zone, Maryland, USA
An unsaturated-zone transport model was used to examine the transport and fate of metolachlor applied to an agricultural site in Maryland, USA. The study site was instrumented to collect data on soil-water content, soil-water potential, ground water levels, major ions, pesticides, and nutrients from the unsaturated zone during 2002-2004. The data set was enhanced with site-specific...
Authors
E.R. Bayless, P. D. Capel, J.E. Barbash, R.M.T. Webb, T.L.C. Hancock, D.C. Lampe
Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness
Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a...
Authors
R.M.T. Webb, M.E. Wieczorek, B. Nolan, T.C. Hancock, Mark Sandstrom, J.E. Barbash, E.R. Bayless, R. Healy, J. Linard
Land-use effects on erosion, sediment yields, and reservoir sedimentation: A case study in the Lago Loiza Basin, Puerto Rico Land-use effects on erosion, sediment yields, and reservoir sedimentation: A case study in the Lago Loiza Basin, Puerto Rico
Lago Loíza impounded in 1953 to supply San Juan, Puerto Rico, with drinking water; by 1994, it had lost 47% of its capacity. To characterize sedimentation in Lago Loíza, a study combining land-use history, hillslope erosion rates, and subbasin sediment yields was conducted. Sedimentation rates during the early part of the reservoir’s operation (1953– 1963) were slightly higher than the...
Authors
Allen Gellis, Richard M. T. Webb, S. McIntyre, William Wolfe
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. Shanley, Brent T. Aulenbach, R. Webb, K. Campbell, R. Hunt, M. Larsen, R.F. Stallard, J. Troester, J.F. Walker
Water, sediment, and nutrient discharge characteristics of Puerto Rico rivers and their potential influence on coral reefs Water, sediment, and nutrient discharge characteristics of Puerto Rico rivers and their potential influence on coral reefs
No abstract available.
Authors
Andrew Warne, Richard M. T. Webb, Matthew Larsen
Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range
Ground water occurrence, movement, and its contribution to streamflow were investigated in Loch Vale, an alpine catchment in the Front Range of the Colorado Rocky Mountains. Hydrogeomorphologic mapping, seismic refraction measurements, and porosity and permeability estimates indicate that talus slopes are the primary ground water reservoir, with a maximum storage capacity that is equal...
Authors
D. Clow, L. Schrott, R. Webb, K. Campbell, A.O. Torizzo, M. Dornblaser
Application of XTOP_PRMS model in Green Lakes Valley, Colorado front range: Runoff simulation and flowpath identification Application of XTOP_PRMS model in Green Lakes Valley, Colorado front range: Runoff simulation and flowpath identification
Stream runoff was simulated from 1996 to 2000 using XTOP_PRMS (coupling of TOPMODEL and Precipitation Runoff Modeling System) model under Modular Modeling System at Martinelli and Green Lake 4 catchments in Green Lakes Valley, Colorado Front Range. Two flowpaths determined by XTOP_PRMS model, surface flow (infiltration-excess overland flow) and subsurface flow, were compared against the...
Authors
F. Liu, Murray Williams, R. Webb, T. Ackerman
Assessment of the habitats, biota, sediments, and water quality near the discharge of primary-treated effluent from the Mayaguez Regional Wastewater Treatment Plant, Bahia de Anasco, Puerto Rico Assessment of the habitats, biota, sediments, and water quality near the discharge of primary-treated effluent from the Mayaguez Regional Wastewater Treatment Plant, Bahia de Anasco, Puerto Rico
No abstract available.
Authors
Richard M. T. Webb, P.D. Collar, W. Schwab, Carlos Goenaga, J.R. Gracia, Roberto Castro
Sedimentation survey of Lago La Plata, Puerto Rico, October 1998 Sedimentation survey of Lago La Plata, Puerto Rico, October 1998
No abstract available.
Authors
Luis Soler-Lopez, Richard M. T. Webb, Ramon Carrasquillo-Nieves
Science and Products
Filter Total Items: 37
Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico
Coral reefs, the foundation and primary structure of many highly productive and diverse tropical marine ecosystems, have been degraded by human activity in much of the earth's tropical oceans. To contribute to improved understanding of this problem, the potential relation between river sediment and nutrient discharges and degradation of coral reefs surrounding Puerto Rico was studied...
Authors
M. Larsen, R.M.T. Webb
Using a coupled groundwater/surface-water model to predict climate-change impacts to lakes in the Trout Lake Watershed, northern Wisconsin Using a coupled groundwater/surface-water model to predict climate-change impacts to lakes in the Trout Lake Watershed, northern Wisconsin
A major focus of the U.S. Geological Survey’s Trout Lake Water, Energy, and Biogeochemical Budgets (WEBB) project is the development of a watershed model to allow predictions of hydrologic response to future conditions including land-use and climate change. The coupled groundwater/surface-water model GSFLOW was chosen for this purpose because it could easily incorporate an existing...
Authors
Randall J. Hunt, John Walker, Steven L. Markstrom, Lauren Hay, John Doherty
Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA
Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected...
Authors
T.C. Hancock, Mark Sandstrom, J. Vogel, R.M.T. Webb, E.R. Bayless, J.E. Barbash
Simulated fate and transport of metolachlor in the unsaturated zone, Maryland, USA Simulated fate and transport of metolachlor in the unsaturated zone, Maryland, USA
An unsaturated-zone transport model was used to examine the transport and fate of metolachlor applied to an agricultural site in Maryland, USA. The study site was instrumented to collect data on soil-water content, soil-water potential, ground water levels, major ions, pesticides, and nutrients from the unsaturated zone during 2002-2004. The data set was enhanced with site-specific...
Authors
E.R. Bayless, P. D. Capel, J.E. Barbash, R.M.T. Webb, T.L.C. Hancock, D.C. Lampe
Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness Variations in pesticide leaching related to land use, pesticide properties, and unsaturated zone thickness
Pesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a...
Authors
R.M.T. Webb, M.E. Wieczorek, B. Nolan, T.C. Hancock, Mark Sandstrom, J.E. Barbash, E.R. Bayless, R. Healy, J. Linard
Land-use effects on erosion, sediment yields, and reservoir sedimentation: A case study in the Lago Loiza Basin, Puerto Rico Land-use effects on erosion, sediment yields, and reservoir sedimentation: A case study in the Lago Loiza Basin, Puerto Rico
Lago Loíza impounded in 1953 to supply San Juan, Puerto Rico, with drinking water; by 1994, it had lost 47% of its capacity. To characterize sedimentation in Lago Loíza, a study combining land-use history, hillslope erosion rates, and subbasin sediment yields was conducted. Sedimentation rates during the early part of the reservoir’s operation (1953– 1963) were slightly higher than the...
Authors
Allen Gellis, Richard M. T. Webb, S. McIntyre, William Wolfe
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. Shanley, Brent T. Aulenbach, R. Webb, K. Campbell, R. Hunt, M. Larsen, R.F. Stallard, J. Troester, J.F. Walker
Water, sediment, and nutrient discharge characteristics of Puerto Rico rivers and their potential influence on coral reefs Water, sediment, and nutrient discharge characteristics of Puerto Rico rivers and their potential influence on coral reefs
No abstract available.
Authors
Andrew Warne, Richard M. T. Webb, Matthew Larsen
Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range
Ground water occurrence, movement, and its contribution to streamflow were investigated in Loch Vale, an alpine catchment in the Front Range of the Colorado Rocky Mountains. Hydrogeomorphologic mapping, seismic refraction measurements, and porosity and permeability estimates indicate that talus slopes are the primary ground water reservoir, with a maximum storage capacity that is equal...
Authors
D. Clow, L. Schrott, R. Webb, K. Campbell, A.O. Torizzo, M. Dornblaser
Application of XTOP_PRMS model in Green Lakes Valley, Colorado front range: Runoff simulation and flowpath identification Application of XTOP_PRMS model in Green Lakes Valley, Colorado front range: Runoff simulation and flowpath identification
Stream runoff was simulated from 1996 to 2000 using XTOP_PRMS (coupling of TOPMODEL and Precipitation Runoff Modeling System) model under Modular Modeling System at Martinelli and Green Lake 4 catchments in Green Lakes Valley, Colorado Front Range. Two flowpaths determined by XTOP_PRMS model, surface flow (infiltration-excess overland flow) and subsurface flow, were compared against the...
Authors
F. Liu, Murray Williams, R. Webb, T. Ackerman
Assessment of the habitats, biota, sediments, and water quality near the discharge of primary-treated effluent from the Mayaguez Regional Wastewater Treatment Plant, Bahia de Anasco, Puerto Rico Assessment of the habitats, biota, sediments, and water quality near the discharge of primary-treated effluent from the Mayaguez Regional Wastewater Treatment Plant, Bahia de Anasco, Puerto Rico
No abstract available.
Authors
Richard M. T. Webb, P.D. Collar, W. Schwab, Carlos Goenaga, J.R. Gracia, Roberto Castro
Sedimentation survey of Lago La Plata, Puerto Rico, October 1998 Sedimentation survey of Lago La Plata, Puerto Rico, October 1998
No abstract available.
Authors
Luis Soler-Lopez, Richard M. T. Webb, Ramon Carrasquillo-Nieves