Silvia Terziotti
Associate National Map Liaison for North Carolina and South Carolina. Member of the Integrated Watershed Study NAWQA team.
Biography
History & Highlights
With USGS since 1988, first in the Virginia Water Science Center and with the North Carolina Water Science Center since 1992. GIS Specialist with the Water mission area, and an Associate Liaison with National Geospatial Program since 2012.
Education
Masters in Urban and Regional Planning (1986) Virginia Commonwealth University, Richmond, VA
Bachelor of Science, Psychology (1983) Randolph-Macon College, Ashland, VA
Areas of Expertise
Hydrologic enforcement of elevation data sets. Scale issues involved in model implementation and updating of model parameters using GIS-derived input. StreamStats support and Advisory Team member. NAWQA GIS Support for Integrated Watershed Studies team.
Specialties
Hydrologic model support. Lidar derivatives and hydro-enforcement.
Science and Products
SPARROW Modeling for North Carolina Watersheds
In North Carolina, excessive nutrient and sediment loadings have contributed to the degradation of surface-water quality across the state as a result of agricultural activities and population growth increases. To further understand the influences of human activities and natural processes on surface-water quality, the U.S. Geological Survey (USGS) developed the SPARROW (SPAtially Referenced...
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...
Terziotti, Silvia; Capel, Paul D.; Tesoriero, Anthony J.; Hopple, Jessica A.; Kronholm, Scott C.
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...
Miller, Matthew P.; Tesoriero, Anthony J.; Hood, Krista; Terziotti, Silvia; Wolock, David M. 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...
Kronholm, Scott C.; Capel, Paul D.; Terziotti, Silvia 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...
Wall, John; Doctor, Daniel H.; Terziotti, Silvia 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...
Tesoriero, Anthony J.; Terziotti, Silvia; Abrams, Daniel B.
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...
Harden, Stephen L.; Cuffney, Thomas F.; Terziotti, Silvia; Kolb, Katharine R.
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/...
Weaver, J. Curtis; Terziotti, Silvia; Kolb, Katharine R.; Wagner, Chad R.
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,...
Terziotti, Silvia; McMahon, Gerard; Bell, Amanda H. A regional modeling framework of phosphorus sources and transport in streams of the southeastern United States
We applied the SPARROW model to estimate phosphorus transport from catchments to stream reaches and subsequent delivery to major receiving water bodies in the Southeastern United States (U.S.). We show that six source variables and five land-to-water transport variables are significant (p < 0.05) in explaining 67% of the variability...
Garcia, Ana Maria.; Hoos, Anne B.; Terziotti, Silvia Digital hydrologic networks supporting applications related to spatially referenced regression modeling
Digital hydrologic networks depicting surface-water pathways and their associated drainage catchments provide a key component to hydrologic analysis and modeling. Collectively, they form common spatial units that can be used to frame the descriptions of aquatic and watershed processes. In addition, they provide the ability to simulate and route...
Brakebill, John W.; Wolock, David M.; Terziotti, Silvia
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...
Terziotti, Silvia; Hoos, Anne B.; Harned, Douglas; Garcia, Ana Maria
Trends in Water Quality in the Southeastern United States, 1973-2005
As part of the U.S. Geological Survey National Water-Quality Assessment Program, water-quality data for 334 streams in eight States of the Southeastern United States were assessed for trends from 1973 to 2005. Forty-four U.S. Geological Survey sites were examined for trends in pH, specific conductance, and dissolved oxygen, and in concentrations...
Harned, Douglas A.; Staub, Erik L.; Peak, Kelly L.; Tighe, Kirsten M.; Terziotti, Silvia
Geomorphological Features of North Carolina Dataset Released
Three statewide datasets were compiled to provide information on geomorphological features in North Carolina. Datasets include state-wide coverages of geomorphon common forms, landscape openness, and slope area index. Datasets were generated from light detection and ranging (lidar) derived digital elevation models at 10 ft. or 30 ft. resolution.