Silvia spent most of her career with the Water Mission Area in USGS, first in the Virginia Water Science Center and then with the South Atlantic Water Science Center. She served as a GIS Specialist, Team lead and Project Chief for numerous hydrologic studies over the years. She has also served on many technical advisory teams addressing geospatial needs, with an emphasis on lidar applications and
Professional Experience
Hydrologic and geomorphologic derivatives from high-resolution elevation data sets. StreamStats support and Advisory Team member.
Education and Certifications
Masters in Urban and Regional Planning (1986) Virginia Commonwealth University, Richmond, VA
Bachelor of Science, Psychology (1983) Randolph-Macon College, Ashland, VA
Science and Products
Indicators of Hydrologic Alteration in North Carolina Catchments: Small Ponds and Artificial Drainage
Alterations to stream hydrology, which include changes in stream geomorphology, are primary impacts of anthropogenic disruption. In North Carolina, hydrological alterations lead to environmental impacts through degraded ecosystems and water quality. In collaboration with the North Carolina Department of Environmental Quality, Division of Mitigation Services (DMS), the USGS South Atlantic Water Sci
Nitrogen sources to and export from the Chesapeake Bay watershed, 1950 to 2050
This U.S. Geological Survey data release contains datasets that combine past data with future projections of nitrogen sources and nitrogen export to the Chesapeake Bay watershed for the years 1950-2050. To help understand the effect of human and environmental changes over this time period, data for nitrogen sources from wastewater, agricultural fertilizer and manure, and atmospheric deposition are
Estimates of atmospheric inorganic nitrogen deposition to the Chesapeake Bay watershed, 1950-2050
Reactive nitrogen is transported from the atmosphere to the landscape as wet and dry deposition that contributes to annual nitrogen loads to the Chesapeake Bay. Estimates of atmospheric inorganic nitrogen deposition to the Chesapeake Bay watershed during 1950 to 2050 are presented, and are based on field measurements, model simulations, statistical relations, and surrogate constituents used for es
Input and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
This data release contains a boosted regression tree (BRT) model (written in the R programming language), and the input and output data from that model that were used to relate base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics. The input data consists of two types of information: 1) surface water nitrate concentrations collected by the USGS and partnerin
Indicators of Hydrologic Alteration in North Carolina Catchments
Alterations to stream hydrology, which includes changes in stream geomorphology, are primary impacts of anthropogenic disruption. In North Carolina, hydrological alterations lead to environmental impacts through degraded ecosystems and water quality. In collaboration with the North Carolina Department of Environmental Quality, Division of Mitigation Services (DMS), the USGS South Atlantic Water Sc
Dataset of SPARROW model input and predictions for total nitrogen and total phosphorus in North Carolina
To better understand the influence of human activities and natural processes on surface-water quality, the U.S. Geological Survey (USGS) developed the SPARROW (SPAtially Referenced Regressions On Watershed attributes) (Schwarz and others, 2006; Alexander and others, 2008) model. The framework is used to relate water-quality monitoring data to sources and watershed characteristics that affect the f
SPARROW model dataset for total suspended solids in North Carolina, including simulated stream loads
To better understand the influence of human activities and natural processes on surface-water quality, the U.S. Geological Survey (USGS) developed the SPARROW (SPAtially Referenced Regressions On Watershed attributes) (Schwarz and others, 2006; Alexander and others, 2008) model. The framework is used to relate water-quality monitoring data to sources and watershed characteristics that affect the f
Geomorphological Features of North Carolina
Three statewide datasets were compiled to provide information on the geomorphology for North Carolina. Geomorphology is commonly a missing element in many Earth-surface process models, thus it is essential to extract this missing information from available DEMs and use it to inform models and better understand the area of interest. For these threee datasets, information was extracted and post proc
Datasets and metadata for estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
This USGS data release contains datasets, metadata, and figures associated with estimating nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology.
There are three shapefiles with associated metadata and figures representing the shapefiles:
Catchments_GWcontribN.shp: NHDPlus catchment estimates of groundwater contribution of nitra
Source and model output layers used for the prediction and display of the probability of elevated concentrations of redox-sensitive constituents in groundwater in the Fox-Wolf-Peshtigo watershed in Wisconsin and Michigan
This USGS data release contains 1-kilometer resolution source-layer rasters used to predict redox conditions and contaminant concentrations in groundwater in the Fox-Wolf-Peshtigo watershed in Wisconsin and Michigan using random forest classification. The model output layers are 1-kilometer resolution rasters of the predicted probability of elevated concentrations of nitrate, iron, and arsenic. Th
Mapping watershed potential to contribute phosphorus from geologic materials to receiving streams, southeastern United States
As part of the southeastern United States SPARROW (SPAtially Referenced Regressions On Watershed attributes) water-quality model implementation, the U.S. Geological Survey created a dataset to characterize the contribution of phosphorus to streams from weathering and erosion of surficial geologic materials. SPARROW provides estimates of total nitrogen and phosphorus loads in surface waters from po
Filter Total Items: 35
Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050
ForewordSustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term e
Authors
John W. Clune, Paul D. Capel, Matthew P. Miller, Douglas A. Burns, Andrew J. Sekellick, Peter R. Claggett, Richard H. Coupe, Rosemary M. Fanelli, Ana Maria Garcia, Jeff P. Raffensperger, Silvia Terziotti, Gopal Bhatt, Joel D. Blomquist, Kristina G. Hopkins, Jennifer L. Keisman, Lewis C. Linker, Gary W. Shenk, Richard A. Smith, Alex Soroka, James S. Webber, David M. Wolock, Qian Zhang
Factors affecting nitrate concentrations in stream base flow
Elevated nitrogen concentrations in streams and rivers in the Chesapeake Bay watershed have adversely affected the ecosystem health of the bay. Much of this nitrogen is derived as nitrate from groundwater that discharges to streams as base flow. In this study, boosted regression trees (BRTs) were used to relate nitrate concentrations in base flow (n = 156) to explanatory variables describing nitro
Authors
Susan Wherry, Anthony J. Tesoriero, Silvia Terziotti
Elevation-derived hydrography acquisition specifications
Hydrographic features derived from U.S. Geological Survey (USGS) 3D Elevation Program data, and collected for use by the USGS, must meet the specifications described in this document. The specifications described herein pertain to the final product delivered to the USGS, not to methods used to derive the hydrographic features. The specifications describe the collection area, spatial reference syst
Authors
Silvia Terziotti, Christy-Ann Archuleta
Elevation-derived hydrography—Representation, extraction, attribution, and delineation rules
With the increasing availability of 3D Elevation Program (3DEP) quality high resolution elevation data across the United States and the pressing need for better integrated elevation and hydrography data, the U.S. Geological Survey is developing guidance to improve the horizontal and vertical alignment of these datasets. The U.S. Geological Survey is providing the Elevation-Derived Hydrography—Acqu
Authors
Christy-Ann Archuleta, Silvia Terziotti
Estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
The water quality of the Chesapeake Bay may be adversely affected by dissolved nitrate carried in groundwater discharge to streams. To estimate the concentrations, loads, and yields of nitrate from groundwater to streams for the Chesapeake Bay watershed, a regression model was developed based on measured nitrate concentrations from 156 small streams with watersheds less than 500 square miles (mi2
Authors
Silvia Terziotti, Paul D. Capel, Anthony J. Tesoriero, Jessica A. Hopple, Scott C. Kronholm
Estimating discharge and nonpoint source nitrate loading to streams from three end‐member pathways using high‐frequency water quality data
The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high‐frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the c
Authors
Matthew P. Miller, Anthony J. Tesoriero, Krista Hood, Silvia Terziotti, David M. Wolock
Statistically extracted fundamental watershed variables for estimating the loads of total nitrogen in small streams
Accurate estimation of total nitrogen loads is essential for evaluating conditions in the aquatic environment. Extrapolation of estimates beyond measured streams will greatly expand our understanding of total nitrogen loading to streams. Recursive partitioning and random forest regression were used to assess 85 geospatial, environmental, and watershed variables across 636 small (<585 km2) watershe
Authors
Scott C. Kronholm, Paul D. Capel, Silvia Terziotti
Predicting redox conditions in groundwater at a regional scale
Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samples
Authors
Anthony J. Tesoriero, Silvia Terziotti, Daniel B. Abrams
A semi-automated tool for reducing the creation of false closed depressions from a filled LIDAR-derived digital elevation model
Closed depressions on the land surface can be identified by ‘filling’ a digital elevation model (DEM) and subtracting the filled model from the original DEM. However, automated methods suffer from artificial ‘dams’ where surface streams cross under bridges and through culverts. Removal of these false depressions from an elevation model is difficult due to the lack of bridge and culvert inventories
Authors
John Wall, Daniel H. Doctor, Silvia Terziotti
Relation of watershed setting and stream nutrient yields at selected sites in central and eastern North Carolina, 1997-2008
Data collected between 1997 and 2008 at 48 stream sites were used to characterize relations between watershed settings and stream nutrient yields throughout central and eastern North Carolina. The focus of the investigation was to identify environmental variables in watersheds that influence nutrient export for supporting the development and prioritization of management strategies for restoring nu
Authors
Stephen L. Harden, Thomas F. Cuffney, Silvia Terziotti, Katharine R. Kolb
Representation of regional urban development conditions using a watershed-based gradient study design
As part of the U.S. Geological Survey National Water-Quality Assessment Program, the effects of urbanization on stream ecosystems (EUSE) have been intensively investigated in nine metropolitan areas in the United States, including Boston, Massachusetts; Atlanta, Georgia; Birmingham, Alabama; Raleigh, North Carolina; Salt Lake City, Utah; Denver, Colorado; Dallas–Fort Worth, Texas; Portland, Oregon
Authors
Silvia Terziotti, Gerard McMahon, Amanda H. Bell
StreamStats in North Carolina: a water-resources Web application
A statewide StreamStats application for North Carolina was developed in cooperation with the North Carolina Department of Transportation following completion of a pilot application for the upper French Broad River basin in western North Carolina (Wagner and others, 2009). StreamStats for North Carolina, available at http://water.usgs.gov/osw/streamstats/north_carolina.html, is a Web-based Geograph
Authors
J. Curtis Weaver, Silvia Terziotti, Katharine R. Kolb, Chad R. Wagner
Filter Total Items: 27
Racetrack Playa in Death Valley, California, is shown as an example of playa feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types but may not have th
Science and Products
- Data
Indicators of Hydrologic Alteration in North Carolina Catchments: Small Ponds and Artificial Drainage
Alterations to stream hydrology, which include changes in stream geomorphology, are primary impacts of anthropogenic disruption. In North Carolina, hydrological alterations lead to environmental impacts through degraded ecosystems and water quality. In collaboration with the North Carolina Department of Environmental Quality, Division of Mitigation Services (DMS), the USGS South Atlantic Water SciNitrogen sources to and export from the Chesapeake Bay watershed, 1950 to 2050
This U.S. Geological Survey data release contains datasets that combine past data with future projections of nitrogen sources and nitrogen export to the Chesapeake Bay watershed for the years 1950-2050. To help understand the effect of human and environmental changes over this time period, data for nitrogen sources from wastewater, agricultural fertilizer and manure, and atmospheric deposition areEstimates of atmospheric inorganic nitrogen deposition to the Chesapeake Bay watershed, 1950-2050
Reactive nitrogen is transported from the atmosphere to the landscape as wet and dry deposition that contributes to annual nitrogen loads to the Chesapeake Bay. Estimates of atmospheric inorganic nitrogen deposition to the Chesapeake Bay watershed during 1950 to 2050 are presented, and are based on field measurements, model simulations, statistical relations, and surrogate constituents used for esInput and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
This data release contains a boosted regression tree (BRT) model (written in the R programming language), and the input and output data from that model that were used to relate base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics. The input data consists of two types of information: 1) surface water nitrate concentrations collected by the USGS and partnerinIndicators of Hydrologic Alteration in North Carolina Catchments
Alterations to stream hydrology, which includes changes in stream geomorphology, are primary impacts of anthropogenic disruption. In North Carolina, hydrological alterations lead to environmental impacts through degraded ecosystems and water quality. In collaboration with the North Carolina Department of Environmental Quality, Division of Mitigation Services (DMS), the USGS South Atlantic Water ScDataset of SPARROW model input and predictions for total nitrogen and total phosphorus in North Carolina
To better understand the influence of human activities and natural processes on surface-water quality, the U.S. Geological Survey (USGS) developed the SPARROW (SPAtially Referenced Regressions On Watershed attributes) (Schwarz and others, 2006; Alexander and others, 2008) model. The framework is used to relate water-quality monitoring data to sources and watershed characteristics that affect the fSPARROW model dataset for total suspended solids in North Carolina, including simulated stream loads
To better understand the influence of human activities and natural processes on surface-water quality, the U.S. Geological Survey (USGS) developed the SPARROW (SPAtially Referenced Regressions On Watershed attributes) (Schwarz and others, 2006; Alexander and others, 2008) model. The framework is used to relate water-quality monitoring data to sources and watershed characteristics that affect the fGeomorphological Features of North Carolina
Three statewide datasets were compiled to provide information on the geomorphology for North Carolina. Geomorphology is commonly a missing element in many Earth-surface process models, thus it is essential to extract this missing information from available DEMs and use it to inform models and better understand the area of interest. For these threee datasets, information was extracted and post procDatasets and metadata for estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
This USGS data release contains datasets, metadata, and figures associated with estimating nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology. There are three shapefiles with associated metadata and figures representing the shapefiles: Catchments_GWcontribN.shp: NHDPlus catchment estimates of groundwater contribution of nitraSource and model output layers used for the prediction and display of the probability of elevated concentrations of redox-sensitive constituents in groundwater in the Fox-Wolf-Peshtigo watershed in Wisconsin and Michigan
This USGS data release contains 1-kilometer resolution source-layer rasters used to predict redox conditions and contaminant concentrations in groundwater in the Fox-Wolf-Peshtigo watershed in Wisconsin and Michigan using random forest classification. The model output layers are 1-kilometer resolution rasters of the predicted probability of elevated concentrations of nitrate, iron, and arsenic. Th - Maps
Mapping watershed potential to contribute phosphorus from geologic materials to receiving streams, southeastern United States
As part of the southeastern United States SPARROW (SPAtially Referenced Regressions On Watershed attributes) water-quality model implementation, the U.S. Geological Survey created a dataset to characterize the contribution of phosphorus to streams from weathering and erosion of surficial geologic materials. SPARROW provides estimates of total nitrogen and phosphorus loads in surface waters from po - Publications
Filter Total Items: 35
Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050
ForewordSustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term eAuthorsJohn W. Clune, Paul D. Capel, Matthew P. Miller, Douglas A. Burns, Andrew J. Sekellick, Peter R. Claggett, Richard H. Coupe, Rosemary M. Fanelli, Ana Maria Garcia, Jeff P. Raffensperger, Silvia Terziotti, Gopal Bhatt, Joel D. Blomquist, Kristina G. Hopkins, Jennifer L. Keisman, Lewis C. Linker, Gary W. Shenk, Richard A. Smith, Alex Soroka, James S. Webber, David M. Wolock, Qian ZhangFactors affecting nitrate concentrations in stream base flow
Elevated nitrogen concentrations in streams and rivers in the Chesapeake Bay watershed have adversely affected the ecosystem health of the bay. Much of this nitrogen is derived as nitrate from groundwater that discharges to streams as base flow. In this study, boosted regression trees (BRTs) were used to relate nitrate concentrations in base flow (n = 156) to explanatory variables describing nitroAuthorsSusan Wherry, Anthony J. Tesoriero, Silvia TerziottiElevation-derived hydrography acquisition specifications
Hydrographic features derived from U.S. Geological Survey (USGS) 3D Elevation Program data, and collected for use by the USGS, must meet the specifications described in this document. The specifications described herein pertain to the final product delivered to the USGS, not to methods used to derive the hydrographic features. The specifications describe the collection area, spatial reference systAuthorsSilvia Terziotti, Christy-Ann ArchuletaElevation-derived hydrography—Representation, extraction, attribution, and delineation rules
With the increasing availability of 3D Elevation Program (3DEP) quality high resolution elevation data across the United States and the pressing need for better integrated elevation and hydrography data, the U.S. Geological Survey is developing guidance to improve the horizontal and vertical alignment of these datasets. The U.S. Geological Survey is providing the Elevation-Derived Hydrography—AcquAuthorsChristy-Ann Archuleta, Silvia TerziottiEstimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
The water quality of the Chesapeake Bay may be adversely affected by dissolved nitrate carried in groundwater discharge to streams. To estimate the concentrations, loads, and yields of nitrate from groundwater to streams for the Chesapeake Bay watershed, a regression model was developed based on measured nitrate concentrations from 156 small streams with watersheds less than 500 square miles (mi2AuthorsSilvia Terziotti, Paul D. Capel, Anthony J. Tesoriero, Jessica A. Hopple, Scott C. KronholmEstimating discharge and nonpoint source nitrate loading to streams from three end‐member pathways using high‐frequency water quality data
The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high‐frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the cAuthorsMatthew P. Miller, Anthony J. Tesoriero, Krista Hood, Silvia Terziotti, David M. WolockStatistically extracted fundamental watershed variables for estimating the loads of total nitrogen in small streams
Accurate estimation of total nitrogen loads is essential for evaluating conditions in the aquatic environment. Extrapolation of estimates beyond measured streams will greatly expand our understanding of total nitrogen loading to streams. Recursive partitioning and random forest regression were used to assess 85 geospatial, environmental, and watershed variables across 636 small (<585 km2) watersheAuthorsScott C. Kronholm, Paul D. Capel, Silvia TerziottiPredicting redox conditions in groundwater at a regional scale
Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samplesAuthorsAnthony J. Tesoriero, Silvia Terziotti, Daniel B. AbramsA semi-automated tool for reducing the creation of false closed depressions from a filled LIDAR-derived digital elevation model
Closed depressions on the land surface can be identified by ‘filling’ a digital elevation model (DEM) and subtracting the filled model from the original DEM. However, automated methods suffer from artificial ‘dams’ where surface streams cross under bridges and through culverts. Removal of these false depressions from an elevation model is difficult due to the lack of bridge and culvert inventoriesAuthorsJohn Wall, Daniel H. Doctor, Silvia TerziottiRelation of watershed setting and stream nutrient yields at selected sites in central and eastern North Carolina, 1997-2008
Data collected between 1997 and 2008 at 48 stream sites were used to characterize relations between watershed settings and stream nutrient yields throughout central and eastern North Carolina. The focus of the investigation was to identify environmental variables in watersheds that influence nutrient export for supporting the development and prioritization of management strategies for restoring nuAuthorsStephen L. Harden, Thomas F. Cuffney, Silvia Terziotti, Katharine R. KolbRepresentation of regional urban development conditions using a watershed-based gradient study design
As part of the U.S. Geological Survey National Water-Quality Assessment Program, the effects of urbanization on stream ecosystems (EUSE) have been intensively investigated in nine metropolitan areas in the United States, including Boston, Massachusetts; Atlanta, Georgia; Birmingham, Alabama; Raleigh, North Carolina; Salt Lake City, Utah; Denver, Colorado; Dallas–Fort Worth, Texas; Portland, OregonAuthorsSilvia Terziotti, Gerard McMahon, Amanda H. BellStreamStats in North Carolina: a water-resources Web application
A statewide StreamStats application for North Carolina was developed in cooperation with the North Carolina Department of Transportation following completion of a pilot application for the upper French Broad River basin in western North Carolina (Wagner and others, 2009). StreamStats for North Carolina, available at http://water.usgs.gov/osw/streamstats/north_carolina.html, is a Web-based GeographAuthorsJ. Curtis Weaver, Silvia Terziotti, Katharine R. Kolb, Chad R. Wagner - Multimedia
Filter Total Items: 27link
Racetrack Playa in Death Valley, California, is shown as an example of playa feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types but may not have th