Sheila Murphy
Sheila Murphy is a Research Hydrologist for the USGS Water Resources Mission Area.
Sheila Murphy is a research hydrologist who focuses on how disturbances (such as wildfire, floods, hurricanes, land use change) alter watershed response, water quality, and water quantity. Her recent research has evaluated the effects of wildfire on water quality in the western U.S., and the hydrologic and geochemical responses to land cover change and hurricanes in a tropical forest in Puerto Rico.
Science and Products
Filter Total Items: 58
A unified assessment of hydrological and biogeochemical responses in research watersheds in Eastern Puerto Rico using runoff-concentration relations
An examination of the relation between runoff rate, R, and concentration, C, of twelve major constituents in four small watersheds in eastern Puerto Rico demonstrates a consistent pattern of responses. For solutes that are not substantially bioactive (alkalinity, silica, calcium, magnesium, sodium, and chloride), the log(R)–log(C) relation is almost linear and can be described as a...
Authors
Robert F. Stallard, Sheila F. Murphy
Evaluation of wastewater contaminant transport in surface waters using verified Lagrangian sampling
Contaminants released from wastewater treatment plants can persist in surface waters for substantial distances. Much research has gone into evaluating the fate and transport of these contaminants, but this work has often assumed constant flow from wastewater treatment plants. However, effluent discharge commonly varies widely over a 24-hour period, and this variation controls contaminant...
Authors
Ronald C. Antweiler, Jeffrey H. Writer, Sheila F. Murphy
Weathering, landscape equilibrium, and carbon in four watersheds in eastern Puerto Rico: Chapter H in Water quality and landscape processes of four watersheds in eastern Puerto Rico
The U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program research in eastern Puerto Rico involves a double pair-wise comparison of four montane river basins, two on granitic bedrock and two on fine-grained volcaniclastic bedrock; for each rock type, one is forested and the other is developed. A confounding factor in this comparison is that the developed...
Authors
Robert F. Stallard
Land use, population dynamics, and land-cover change in eastern Puerto Rico: Chapter B in Water quality and landscape processes of four watersheds in eastern Puerto Rico
We assessed current and historic land use and land cover in the Luquillo Mountains and surrounding area in eastern Puerto Rico, including four small subwatersheds that are study watersheds of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program. This region occupies an area of 1,616 square kilometers, about 18 percent of the total land in Puerto Rico...
Authors
William A. Gould, Sebastián Martinuzzi, Isabel K. Pares-Ramos, Sheila F. Murphy, Robert F. Stallard
Effects of earthworms on slopewash, surface runoff, and fine-litter transport on a humid-tropical forested hillslope in eastern Puerto Rico: Chapter G in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Rainfall, slopewash (the erosion of soil particles), surface runoff, and fine-litter transport were measured in tropical wet forest on a hillslope in the Luquillo Experimental Forest, Puerto Rico, from February 1998 until April 2000. Slopewash data were collected using Gerlach troughs at eight plots, each 2 square meters in area. Earthworms were excluded by electroshocking from four...
Authors
Matthew C. Larsen, Zhigang Liu Liu, Xiaoming Zou
Landslides and sediment budgets in four watersheds in eastern Puerto Rico: Chapter F in Water quality and landscape processes of four watersheds in eastern Puerto Rico
The low-latitude regions of the Earth are undergoing profound, rapid landscape change as forests are converted to agriculture to support growing population. Understanding the effects of these land-use changes requires analysis of watershed-scale geomorphic processes to better inform and manage this usually disorganized process. The investigation of hillslope erosion and the development...
Authors
Matthew C. Larsen
Hydrology and climate of four watersheds in eastern Puerto Rico: Chapter C in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Puerto Rico lies directly in the path of the easterly trade winds, which deliver steady rainfall to the mountains and steer tropical wave systems toward the island. Hurricanes and tropical storms derived from these tropical waves differ in frequency and intensity, contributing to substantial interannual variation in precipitation and stream discharge. Puerto Rico's steep topography and...
Authors
Sheila F. Murphy, Robert F. Stallard
Atmospheric inputs to watersheds of the Luquillo Mountains in eastern Puerto Rico: Chapter D in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Twenty years of precipitation-chemistry data from the National Atmospheric Deposition Program site at El Verde, Puerto Rico, demonstrate that three major sources control the composition of solutes in rain in eastern Puerto Rico. In order of importance, these sources are marine salts, temperate contamination from the Northern Hemisphere, and Sahara Desert dust. Marine salts are a source...
Authors
Robert F. Stallard
Water quality and mass transport in four watersheds in eastern Puerto Rico: Chapter E in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Water quality of four small watersheds in eastern Puerto Rico has been monitored since 1991 as part of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets program. These watersheds represent a montane, humid-tropical environment and differ in geology and land cover. Two watersheds are located on granitic rocks, and two are located on volcaniclastic rock. For each...
Authors
Robert F. Stallard, Sheila F. Murphy
Physiography, geology, and land cover of four watersheds in eastern Puerto Rico: Chapter A in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Four watersheds with differing geology and land cover in eastern Puerto Rico have been studied on a long-term basis by the U.S. Geological Survey to evaluate water, energy, and biogeochemical budgets. These watersheds are typical of tropical, island-arc settings found in many parts of the world. Two watersheds are located on coarse-grained granitic rocks that weather to quartz- and clay...
Authors
Sheila F. Murphy, Robert F. Stallard, Matthew C. Larsen, William A. Gould
Weathering processes in the Rio Icacos and Rio Mameyes watersheds in Eastern Puerto Rico: Chapter I in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Streams draining watersheds of the two dominant lithologies (quartz diorite and volcaniclastic rock) in the Luquillo Experimental Forest of eastern Puerto Rico have very high fluxes of bedrock weathering products. The Río Blanco quartz diorite in the Icacos watershed and the Fajardo volcaniclastic rocks in the Mameyes watershed have some of the fastest documented rates of chemical...
Authors
Heather L. Buss, Arthur F. White
Effects of flow regime on stream turbidity and suspended solids after wildfire, Colorado Front Range
Wildfires occur frequently in the Colorado Front Range and can alter the hydrological response of watersheds, yet little information exists on the impact of flow regime and storm events on post-wildfire water quality. The flow regime in the region is characterized by base-flow conditions during much of the year and increased runoff during spring snowmelt and summer convective storms. The...
Authors
Sheila F. Murphy, R. Blaine McCleskey, Jeffrey H. Writer
Science and Products
Filter Total Items: 58
A unified assessment of hydrological and biogeochemical responses in research watersheds in Eastern Puerto Rico using runoff-concentration relations
An examination of the relation between runoff rate, R, and concentration, C, of twelve major constituents in four small watersheds in eastern Puerto Rico demonstrates a consistent pattern of responses. For solutes that are not substantially bioactive (alkalinity, silica, calcium, magnesium, sodium, and chloride), the log(R)–log(C) relation is almost linear and can be described as a...
Authors
Robert F. Stallard, Sheila F. Murphy
Evaluation of wastewater contaminant transport in surface waters using verified Lagrangian sampling
Contaminants released from wastewater treatment plants can persist in surface waters for substantial distances. Much research has gone into evaluating the fate and transport of these contaminants, but this work has often assumed constant flow from wastewater treatment plants. However, effluent discharge commonly varies widely over a 24-hour period, and this variation controls contaminant...
Authors
Ronald C. Antweiler, Jeffrey H. Writer, Sheila F. Murphy
Weathering, landscape equilibrium, and carbon in four watersheds in eastern Puerto Rico: Chapter H in Water quality and landscape processes of four watersheds in eastern Puerto Rico
The U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program research in eastern Puerto Rico involves a double pair-wise comparison of four montane river basins, two on granitic bedrock and two on fine-grained volcaniclastic bedrock; for each rock type, one is forested and the other is developed. A confounding factor in this comparison is that the developed...
Authors
Robert F. Stallard
Land use, population dynamics, and land-cover change in eastern Puerto Rico: Chapter B in Water quality and landscape processes of four watersheds in eastern Puerto Rico
We assessed current and historic land use and land cover in the Luquillo Mountains and surrounding area in eastern Puerto Rico, including four small subwatersheds that are study watersheds of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program. This region occupies an area of 1,616 square kilometers, about 18 percent of the total land in Puerto Rico...
Authors
William A. Gould, Sebastián Martinuzzi, Isabel K. Pares-Ramos, Sheila F. Murphy, Robert F. Stallard
Effects of earthworms on slopewash, surface runoff, and fine-litter transport on a humid-tropical forested hillslope in eastern Puerto Rico: Chapter G in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Rainfall, slopewash (the erosion of soil particles), surface runoff, and fine-litter transport were measured in tropical wet forest on a hillslope in the Luquillo Experimental Forest, Puerto Rico, from February 1998 until April 2000. Slopewash data were collected using Gerlach troughs at eight plots, each 2 square meters in area. Earthworms were excluded by electroshocking from four...
Authors
Matthew C. Larsen, Zhigang Liu Liu, Xiaoming Zou
Landslides and sediment budgets in four watersheds in eastern Puerto Rico: Chapter F in Water quality and landscape processes of four watersheds in eastern Puerto Rico
The low-latitude regions of the Earth are undergoing profound, rapid landscape change as forests are converted to agriculture to support growing population. Understanding the effects of these land-use changes requires analysis of watershed-scale geomorphic processes to better inform and manage this usually disorganized process. The investigation of hillslope erosion and the development...
Authors
Matthew C. Larsen
Hydrology and climate of four watersheds in eastern Puerto Rico: Chapter C in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Puerto Rico lies directly in the path of the easterly trade winds, which deliver steady rainfall to the mountains and steer tropical wave systems toward the island. Hurricanes and tropical storms derived from these tropical waves differ in frequency and intensity, contributing to substantial interannual variation in precipitation and stream discharge. Puerto Rico's steep topography and...
Authors
Sheila F. Murphy, Robert F. Stallard
Atmospheric inputs to watersheds of the Luquillo Mountains in eastern Puerto Rico: Chapter D in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Twenty years of precipitation-chemistry data from the National Atmospheric Deposition Program site at El Verde, Puerto Rico, demonstrate that three major sources control the composition of solutes in rain in eastern Puerto Rico. In order of importance, these sources are marine salts, temperate contamination from the Northern Hemisphere, and Sahara Desert dust. Marine salts are a source...
Authors
Robert F. Stallard
Water quality and mass transport in four watersheds in eastern Puerto Rico: Chapter E in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Water quality of four small watersheds in eastern Puerto Rico has been monitored since 1991 as part of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets program. These watersheds represent a montane, humid-tropical environment and differ in geology and land cover. Two watersheds are located on granitic rocks, and two are located on volcaniclastic rock. For each...
Authors
Robert F. Stallard, Sheila F. Murphy
Physiography, geology, and land cover of four watersheds in eastern Puerto Rico: Chapter A in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Four watersheds with differing geology and land cover in eastern Puerto Rico have been studied on a long-term basis by the U.S. Geological Survey to evaluate water, energy, and biogeochemical budgets. These watersheds are typical of tropical, island-arc settings found in many parts of the world. Two watersheds are located on coarse-grained granitic rocks that weather to quartz- and clay...
Authors
Sheila F. Murphy, Robert F. Stallard, Matthew C. Larsen, William A. Gould
Weathering processes in the Rio Icacos and Rio Mameyes watersheds in Eastern Puerto Rico: Chapter I in Water quality and landscape processes of four watersheds in eastern Puerto Rico
Streams draining watersheds of the two dominant lithologies (quartz diorite and volcaniclastic rock) in the Luquillo Experimental Forest of eastern Puerto Rico have very high fluxes of bedrock weathering products. The Río Blanco quartz diorite in the Icacos watershed and the Fajardo volcaniclastic rocks in the Mameyes watershed have some of the fastest documented rates of chemical...
Authors
Heather L. Buss, Arthur F. White
Effects of flow regime on stream turbidity and suspended solids after wildfire, Colorado Front Range
Wildfires occur frequently in the Colorado Front Range and can alter the hydrological response of watersheds, yet little information exists on the impact of flow regime and storm events on post-wildfire water quality. The flow regime in the region is characterized by base-flow conditions during much of the year and increased runoff during spring snowmelt and summer convective storms. The...
Authors
Sheila F. Murphy, R. Blaine McCleskey, Jeffrey H. Writer