Allen C Gellis, Ph.D.
Allen's interests are in the broad area of fluvial geomorphology, with emphasis on understanding the erosion, transport, storage, delivery, and age of fluvial sediment. Much of Allen’s research is focused on developing approaches to understand the significant sources of fine-grained sediment using geochemical tracers or fingerprints at both small and regional watershed scales.
Professional Experience
Present Assignment: Fluvial Geomorphologist for the National Water Quality Assessments (NAWQA) Regional Stream Quality Assessment Team (RSQA)
The NAWQA-RSQA program has multiple objectives: (1) to access the status of ecological conditions in broad regions of the U.S., (2) to understand the relation of contaminants, nutrients, and sediment to ecologic condition and (3) to understand the role of human and natural factors in the occurrence of contaminants, nutrients, and sediment. We have conducted studies in 3 large ecosystems of the United States- the Midwest (MSQA), the Southeast (SESQA), and the Pacific Northwest (PNSQA) with 3 regions remaining. At all the RSQA sites, I develop the data collection for the physical habitat assessments and provide training and support for USGS NAWQA personnel.
My research with NAWQA includes: 1. Using radionuclides (7Be, 210Pbex, 137Cs) to determine the source(s) and age of fine-grained sediment (<0.063mm). 2. Developing appropriate metrics to understand the relation of sediment and channel morphologic stressors on the health of aquatic habitat. 3. Analyzing regional sediment loads and concentrations. My NAWQA research and its interpretations have enormous national implications that include understanding sediment sources at regional scales and determining the physical health of our Nations' rivers. With assistance from Laurel Woodruff, a major study objective of SESQA is to determine if the USGS Geochemical Soils Database (http://pubs.usgs.gov/of/2014/1082/) can be used as a source library for sediment fingerprinting. We are only 2 years into the analysis, and I have not yet published any significant research papers. I did present preliminary results of my sediment sourcing research using radionuclides at the 2014 AGU National Meeting. I am expected to publish several papers over the next year.
Present Assignment: Identifying Sediment Sources in the Sediment Total Maximum Daily Load Process (10 %)
The objective of this study is to bring the science of sediment sourcing to the practitioner level. This includes research on sediment budgets and sediment fingerprinting. The practitioners we are asked to assist include local and state agencies mandated to reduce sediment loads through the Sediment TMDL program. We are currently writing an EPA manual that highlights the methods and approaches used to identify sediment sources and develop sediment budgets.
Previous Assignment: Determining the sources of fine-grained sediment in small watersheds of the Chesapeake Bay
In the Chesapeake Bay, sediment and associated nutrients are having an adverse effect on the living resources and habitat of the Chesapeake
Education and Certifications
Ph.D. in Geology - Dissertation Title: Suspended-Sediment Characteristics In Four Humid Tropical Watersheds Of Contrasting Land Use, Puerto Rico, Colorado State University
M.S. in Geology, Colorado State University
B.S. in Geology, State University of New York at Albany
Science and Products
Pavement alters delivery of sediment and fallout radionuclides to urbanstreams
Stream corridor sources of suspended sediment and phosphorus from an agricultural tributary to the Great Lakes
Combining sediment fingerprinting with age-dating sediment using fallout radionuclides for an agricultural stream, Walnut Creek, Iowa, USA
Preface—Evaluating the response of critical zone processes to human impacts with sediment source fingerprinting
Bank‐derived material dominates fluvial sediment in a suburban Chesapeake Bay watershed
Sediment Source Assessment Using Sediment Fingerprints
Sediment fingerprinting to delineate sources of sediment in the agricultural and forested Smith Creek Watershed, Virginia, USA
Factors influencing fine sediment on stream beds in the Midwestern United States
A method to quantify and value floodplain sediment and nutrient retention ecosystem services
Floodplains provide critical ecosystem services to local and downstream communities by retaining floodwaters, sediments, and nutrients. The dynamic nature of floodplains is such that these areas can both accumulate sediment and nutrients through deposition, and export material downstream through erosion. Therefore, estimating floodplain sediment and nutrient retention should consider the net flux
Floodplain trapping and cycling compared to streambank erosion of sediment and nutrients in an agricultural watershed
Channel response to sediment release: insights from a paired analysis of dam removal
Determining the sources of fine-grained sediment using the Sediment Source Assessment Tool (Sed_SAT)
Science and Products
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Filter Total Items: 51
Pavement alters delivery of sediment and fallout radionuclides to urbanstreams
Sediment from urban impervious surfaces has the potential to be an important vector for contaminants, particularly where stormwater culverts and other buried channels draining large impervious areas exit from underground pipes into open channels. To better understand urban sediment sources and their relation to fallout radionuclides, we collected samples of rainfall, urban sediment (pavement sedimAuthorsAllen C. Gellis, Christopher C. Fuller, Peter C. Van Metre, Barbara Mahler, C. Welty, Andrew Miller, Lucas A Nibert, Zachary Clifton, Jeremy Malen, J.T. KemperStream corridor sources of suspended sediment and phosphorus from an agricultural tributary to the Great Lakes
Fine-grained sediment and phosphorous are major contaminants in the Great Lakes and their tributaries. Plum Creek, Wisconsin (92 km2), a tributary to the Lower Fox River, has a Total Maximum Daily Load (TMDL) requiring reductions of suspended sediment and phosphorus loading by 70% and 77%, respectively. In 2016-18, an integrated sediment fingerprinting and stream corridor-based sediment budget sAuthorsFaith A. Fitzpatrick, James Blount, Leah Kammel, David L. Hoover, Allen C. Gellis, Barbara C. Scudder EikenberryCombining sediment fingerprinting with age-dating sediment using fallout radionuclides for an agricultural stream, Walnut Creek, Iowa, USA
PurposeThe main purpose of this study was to demonstrate the utility of the sediment fingerprinting approach to apportion surface-derived sediment, and then age date that portion using short-lived fallout radionuclides. In systems where a large mass of mobile sediment is in channel storage, age dating provides an understanding of the transfer of sediment through the watershed and the time scales oAuthorsAllen C. Gellis, Christopher C. Fuller, Peter C. Van Metre, Christopher T. Filstrup, Kevin Cole, Timur SabitovPreface—Evaluating the response of critical zone processes to human impacts with sediment source fingerprinting
1) Background: Critical Zone Processes in the Anthropocene The Earth’s Critical Zone encompasses a suite of interconnected processes in the near-surface lithosphere, pedosphere, biosphere, atmosphere, and hydrosphere (Brantley et al., 2007; Lin, 2010) (Fig. 1). Processes and interactions both within and between these various Critical Zone components supports life-sustaining ecosystem services andAuthorsJ. Patrick Laceby, Allen C. Gellis, Alexander J. Koiter, Will H. Blake, Olivier EvrardBank‐derived material dominates fluvial sediment in a suburban Chesapeake Bay watershed
Excess fine sediment is a leading cause of ecological degradation within the Chesapeake Bay watershed. To effectively target sediment mitigation measures, it is necessary to identify and quantify the delivery of sediment sources to local waterbodies.This study examines the contributions of sediment sources within Upper Difficult Run, a suburbanized watershed in Fairfax County, Virginia. A source sAuthorsMatt J. Cashman, Allen C. Gellis, Lillian Gorman Sanisaca, Gregory B. Noe, Vanessa Cogliandro, Anna BakerSediment Source Assessment Using Sediment Fingerprints
ProblemSediment is one of the most common causes of loss of stream-biologic integrity, whether in suspension in the water column, or as deposition on a stream or lake bottom. Fine-grained silts and clays are of particular concern because they can degrade habitat and often carry phosphorus and (or) other contaminants harmful to humans and aquatic life. Sediment-impaired water bodies, usually identiAuthorsAllen C. Gellis, Lillian E. Gorman Sanisaca, Matthew J. CashmanSediment fingerprinting to delineate sources of sediment in the agricultural and forested Smith Creek Watershed, Virginia, USA
The sediment fingerprinting approach was used to apportion fine‐grained sediment to cropland, pasture, forests, and streambanks in the agricultural and forested Smith Creek, watershed, Virginia. Smith Creek is a showcase study area in the Chesapeake Bay watershed, where management actions to reduce nutrients and sediment are being monitored. Analyses of suspended sediment at the downstream and upsAuthorsAllen C. Gellis, Lillian Gorman SanisacaFactors influencing fine sediment on stream beds in the Midwestern United States
Fine sediment (particles <2 mm in diameter) in stream beds has wide-ranging effects on hydraulics, geomorphology, and ecology and is a primary focus for stream quality management in many regions. We identify reach- and basin-scale factors associated with fine sediment in the beds of 83 stream reaches in the Midwestern United States using recursive partitioning of sand-bed and gravel-bed streams anAuthorsChristopher P. Konrad, Allen C. GellisA method to quantify and value floodplain sediment and nutrient retention ecosystem services
Floodplains provide critical ecosystem services to local and downstream communities by retaining floodwaters, sediments, and nutrients. The dynamic nature of floodplains is such that these areas can both accumulate sediment and nutrients through deposition, and export material downstream through erosion. Therefore, estimating floodplain sediment and nutrient retention should consider the net flux
AuthorsKristina G. Hopkins, Gregory B. Noe, Fabiano Franco, Emily J. Pindilli, Stephanie Gordon, Marina Metes, Peter R. Claggett, Allen C. Gellis, Cliff R. Hupp, Dianna M. HoganFloodplain trapping and cycling compared to streambank erosion of sediment and nutrients in an agricultural watershed
Floodplains and streambanks can positively and negatively influence downstream water quality through interacting geomorphic and biogeochemical processes. Few studies have measured those processes in agricultural watersheds. We measured inputs (floodplain sedimentation and dissolved inorganic loading), cycling (floodplain soil nitrogen [N] and phosphorus [P] mineralization), and losses (bank erosioAuthorsJaimie Gillespie, Gregory B. Noe, Cliff R. Hupp, Allen C. Gellis, Edward R. SchenkChannel response to sediment release: insights from a paired analysis of dam removal
Dam removals with unmanaged sediment releases are good opportunities to learn about channel response to abruptly increased bed material supply. Understanding these events is important because they affect aquatic habitats and human uses of floodplains. A longstanding paradigm in geomorphology holds that response rates to landscape disturbance exponentially decay through time. However, a previous stAuthorsMathias J. Collins, Noah P. Snyder, Graham Boardman, William S. Banks, Mary Andrews, Matthew E. Baker, Maricate Conlon, Allen C. Gellis, Serena McClain, Andrew Miller, Peter WilcockDetermining the sources of fine-grained sediment using the Sediment Source Assessment Tool (Sed_SAT)
A sound understanding of sources contributing to instream sediment flux in a watershed is important when developing total maximum daily load (TMDL) management strategies designed to reduce suspended sediment in streams. Sediment fingerprinting and sediment budget approaches are two techniques that, when used jointly, can qualify and quantify the major sources of sediment in a given watershed. TheAuthorsLillian E. Gorman Sanisaca, Allen C. Gellis, David L. Lorenz - Software
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