Andrew Sekellick
Biography
Andrew has worked for the U.S. Geological Survey in Baltimore since 2008, providing Geographic Information Systems (GIS), cartographic, and statistical support to a wide variety of projects. Experience and interests include groundwater modeling, watershed level sediment studies, and water quality modeling.
Current work focuses estimating the effects of Best Management Practices (BMPs) in the Chesapeake Bay watershed and predicting water quality in baseflow and total flow using time sensitive modeling techniques.
Education
M.P.S. Geographic Information Systems, University of Maryland, Baltimore County.
B.S. Geography and Environmental Systems, University of Maryland, Baltimore County.
Science and Products
MD-DE-DC WSC GIS/Dataset Capabilities
Spatial analysts at the MD-DE-DC WSC use Geographic Information Systems to interpret data collected through field reconnaissance and downloaded from internal USGS, other federal, state, and local agencies, academic institutions, industry, and other professional contracting organizations. GIS is used to analyze the data using shapefiles and geodatabased information to help prove or disprove...
MD-DE-DC WSC Modeling Capabilities
USGS models are widely used to predict responses of hydrologic systems to changing stresses, such as increases in precipitation or ground-water pumping rates, as well as to predict the fate and movement of solutes and contaminants in water.
The USGS is at the forefront of devising new techniques and computer software to solve practical problems in the study of water resources....
Sediment dynamics and implications for management: State of the science from long‐term research in the Chesapeake Bay watershed, USA
This review aims to synthesize the current knowledge of sediment dynamics using insights from long‐term research conducted in the watershed draining to the Chesapeake Bay, the largest estuary in the U.S., to inform management actions to restore the estuary and its watershed. The sediment dynamics of the Chesapeake are typical of many impaired...
Noe, Gregory B.; Cashman, Matthew J.; Skalak, Katherine; Gellis, Allen; Hopkins, Kristina G.; Moyer, Douglas L.; Webber, James S.; Benthem, Adam; Maloney, Kelly O.; Brakebill, John; Sekellick, Andrew; Langland, Michael J.; Zhang, Qian; Shenk, Gary Wynee; Keisman, Jennifer L.D.; Hupp, Cliff R. Toward explaining nitrogen and phosphorus trends in Chesapeake Bay tributaries, 1992-2012
Understanding trends in stream chemistry is critical to watershed management, and often complicated by multiple contaminant sources and landscape conditions changing over varying time scales. We adapted spatially-referenced regression (SPARROW) to infer causes of recent nutrient trends in Chesapeake Bay tributaries by relating observed fluxes...
Ator, Scott; Garcia, Ana M.; Schwarz, Gregory E.; Blomquist, Joel; Sekellick, Andrew
Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014
Efforts to restore water quality in Chesapeake Bay and its tributaries often include extensive Best Management Practice (BMP) implementation on agricultural and developed lands. These BMPs include a variety of methods to reduce nutrient and sediment loads, such as cover crops, conservation tillage, urban filtering systems, and other practices....
Sekellick, Andrew J.; Devereux, Olivia H.; Keisman, Jennifer L.D.; Sweeney, Jeffrey S.; Blomquist, Joel D.
Manure and fertilizer inputs to land in the Chesapeake Bay watershed, 1950–2012
Understanding changing nutrient concentrations in surface waters requires quantitative information on changing nutrient sources in contributing watersheds. For example, the proportion of nutrient inputs reaching streams and rivers is directly affected by when and where those nutrients enter the landscape. The goal of this report is to contribute...
Keisman, Jennifer L.; Devereux, Olivia H.; LaMotte, Andrew E.; Sekellick, Andrew J.; Blomquist, Joel D. Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change
Causal attribution of changes in water quality often consists of correlation, qualitative reasoning, listing references to the work of others, or speculation. To better support statements of attribution for water-quality trends, structural equation modeling was used to model the causal factors of total phosphorus loads in the Chesapeake Bay...
Ryberg, Karen R.; Blomquist, Joel D.; Sprague, Lori A.; Sekellick, Andrew J.; Keisman, Jennifer L.
Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012
To assist in understanding sediment loadings and the management of water resources, a bathymetric survey was conducted in the part of Lake Linganore between Boyers Mill Road Bridge and Bens Branch in Frederick County, Maryland. The bathymetric survey was performed in January 2012 by the U.S. Geological Survey, in cooperation with the City of...
Sekellick, Andrew J.; Banks, William S.L.; Myers, Michael K.
Statistical classification of hydrogeologic regions in the fractured rock area of Maryland and parts of the District of Columbia, Virginia, West Virginia, Pennsylvania, and Delaware
Hydrogeologic regions in the fractured rock area of Maryland were classified using geographic information system tools with principal components and cluster analyses. A study area consisting of the 8-digit Hydrologic Unit Code (HUC) watersheds with rivers that flow through the fractured rock area of Maryland and bounded by the Fall Line was...
Fleming, Brandon J.; LaMotte, Andrew E.; Sekellick, Andrew J.
A regional classification of the effectiveness of depressional wetlands at mitigating nitrogen transport to surface waters in the Northern Atlantic Coastal Plain
Nitrogen from nonpoint sources contributes to eutrophication, hypoxia, and related ecological degradation in Atlantic Coastal Plain streams and adjacent coastal estuaries such as Chesapeake Bay and Pamlico Sound. Although denitrification in depressional (non-riparian) wetlands common to the Coastal Plain can be a significant landscape sink for...
Ator, Scott W.; Denver, Judith M.; LaMotte, Andrew E.; Sekellick, Andrew J.
Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009
To assist in understanding sediment and phosphorus loadings and the management of water resources, a bathymetric survey was conducted at Lake Linganore in Frederick County, Maryland in June 2009 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County, Maryland. Position data and water-depth data were collected...
Sekellick, Andrew J.; Banks, S.L.