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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 ( 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