Charles Walker, Ph.D.
Dr. Charles Walker manages the Hydrologic Data Collection Networks (Surface Water, Groundwater and Water-Quality Data Collection) in the Maryland, Delaware and District of Columbia Areas. Chuck specializes in state of the art hydrologic data collection system design, implementation and operation.
Biography
Education
Ph.D. Soil Science, The Pennsylvania State University, University Park, PA.
M.S. Environmental Pollution Control, The Pennsylvania State University, University Park, PA.
B.S. in Environmental Resource Management, The Pennsylvania State University, University Park, PA. Minor: Environmental Engineering.
Professional Experience
2020- pres Associate Director for Data. United States Geological Survey. Manage Hydrologic Data Collection Networks.
2016 – 2020 Supervisory Hydrologist. United States Geological Survey. Supervise hydrologists and hydrologic technicians focusing on water-quality data collection and research.
2016 – 2016 Deputy Center Director (Acting). United States Geological Survey. Worked with senior managers to provide organizational leadership.
2012 – 2020 Water-Quality Specialist. United States Geological Survey. Serve as a technical and quality assurance reviewer for proposals, datasets and reports.
2010 – 2016 Hydrologist. United States Geological Survey. Project leader for water resource investigations.
2006 – 2010 Post-doctoral Research Associate. The Pennsylvania State University, University Park, PA. Developed methods to measure and model estrogen transport through soils.
Referred Journal Articles
Lorah, M.M., C.W. Walker, and D. Graves. 2015. Performance of an anaerobic, static bed, fixed film bioreactor for chlorinated solvent treatment. Biodegradation. 26: 341-357.
Walker, C.W., J. Watson, and C. Williams. 2012. Occurrence of carbamazepine in soils under different land uses receiving wastewater. Journal of Environmental Quality. 41: 1263-1267.
Castellano MJ, Schmidt JP, Kaye JP, Walker C.W., Graham C, Lin H, Dell C. 2011. Soil water controls on heterotrophic respiration. Geoderma doi: 10.1016/j.geoderma.2011.01.020
Walker, C.W., and J. Watson. 2010. Adsorption of estrogens to laboratory materials and filters during sample preparation. Journal of Environmental Quality. 39: 744-748.
Jacobsen, K. L., R.S. Gallagher, M. Burnham, B. B. Bradley, Z. M. Larson, C.W. Walker and J.E. Watson. 2010. Mitigation of Seed Germination Impediments in Hairy Vetch. Agronomy Journal 102: 1346-1350.
Castellano MJ, Schmidt JP, Kaye JP, Walker C.W., Graham C, Lin H, Dell C. 2010. Biogeochemical and hydrological controls on nitrous oxide emissions across an agricultural landscape. Global Change Biology. doi: 10.1111/j.1365-2486.2009.02116.x.
Walker, C.W., J. Watson, and R. Thomas. 2009. Design of a low-cost, flow-through electrical conductivity probe. Applied Engineering in Agriculture 25: 373-376.
Walker, C.W., and H. Lin. 2008. Soil property changes after four decades of wastewater irrigation: A landscape perspective. Catena 73: 63-74.
Walker, C.W., and R.D. Shannon. 2006. Nitrate and phosphate removal effects of compost amendments in wetland mesocosms. Transactions of the ASABE 49:1773-1778.
Walker, C.W., H. Lin, and D.D. Fritton. 2006. Is the tension beneath a tension infiltrometer what we think it is? Vadose Zone Journal 5:860-866.
Lin, H., W.J. Kogelmann, C.W. Walker, and M.A. Bruns. 2006. Soil moisture patterns in a forested catchment: A hydropedological perspective. Geoderma 131:345-368.
Peer-Reviewed Reports
Walker, C.W., Lester, T.R., and Nealen, C.W., 2019, Hydrologic study at Farm Creek Marsh, Dorchester County, Maryland, from April 2015 to April 2016: U.S. Geological Survey Scientific Investigations Report 2019–5032, 12 p., https://doi.org/10.3133/sir20195032.
Walker, C.W., Degnan, J.R., Brayton, M.J., Cruz, R.M., and Lorah, M.M., 2015, Surface geophysics and porewater evaluation at the Lower Darby Creek Area Superfund Site, Philadelphia, Pennsylvania, 2013: U.S. Geological Survey Data Series 927, 6 p., http://dx.doi.org/10.3133/ds927
Lorah, M.M., Walker, C.W., Baker, A.C., Teunis, J.A., Majcher, E.H., Brayton, M.J., Raffensperger, J.P., and Cozzarelli, I.M., 2014, Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009–12: U.S. Geological Survey Scientific Investigations Report 2014–5140, 89 p.
Dieter, C.A., Koterba, M.T., Zapecza, O.S., Walker, C.W., and Rice, D.E., 2013, Hydrogeologic framework, hydrology, and water quality in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11: U.S. Geological Survey Scientific Investigations Report 2012–5263, 219 p. First posted January 17, 2013.
Conference Abstracts
Walker, C.W., M. Lorah, A. Baker, and D. Graves. 2012. Pilot-scale anaerobic bioreactor system for removal of 1,1,2,2-tetrachloroethane and trichloroethane from contaminated groundwater at Aberdeen Proving Ground, Maryland, 2011. Eighth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, CA.
Lorah, M., C.W. Walker, J. Teunis, D. Graves and W. Schneider. 2011. Transformation products and rates for chlorinated ethanes and ethenes by an anaerobic dechlorinating consortium. Battelle Bioremediation Conference. Reno, NV
Lorah, M., C.W. Walker, A. Baker, and D. Graves, J. Wrobel. 2010. Removing chlorinated solvents from contaminated groundwater using an above-ground bioreactor system. 19th Annual Maryland Ground Water Symposium. Baltimore, MD.
Walker, C.W., J. Watson, Z. Larson, and J. Gaudlip. 2009. The Pennsylvania State University’s Wastewater Irrigation System: 30 billion gallons and still spraying. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.
Larson, Z., C.W. Walker, and J. Watson. 2009. The effects of long term wastewater irrigation on soil physical properties. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.
Watson, J., C.W. Walker and Z. Larson. 2009. Concentration dependent sorption of estrone to soil. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.
Petersen, G., B. Ketchum, C.W. Walker and A. Khouzani. 2009. A digital introductory soils course for the virtual classroom. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Pittsburgh, PA.
Walker, C.W., J. Watson, J. Dec, and Z. Larson. 2008. Wastewater irrigation: The potential to increase biofuel production while removing endocrine disrupting hormones. 2008 Mid-Atlantic Regional Water Resources Research Conference: The Water-Energy Nexus: A Necessary Synergy for the 21st Century. Shepherdstown, West Virginia.
Walker, C.W., J. Watson, and R. Thomas. 2007. Design of a low-cost, flow-through electrical conductivity probe. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.
Walker, C.W., H. Lin, X. Zhou, Z. Zhang, and P. Reed. 2007. Simple electronic device for measuring shallow ground water level. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.
Watson, J., and C.W. Walker. 2007. Soil Water Variability and Crop Yields. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.
Castellano, M., C.W. Walker, J. Schmidt, C. Dell, J. Kaye, and H. Lin. 2007. Soil nutrient transport and transformation during extreme water table fluctuations in an agro-ecosystem. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, New Orleans, Louisiana.
Luo, L., H. Lin, and C.W. Walker. 2007. Quantitative relationship between soil structure and preferential flow and transport in contrasting soils and land uses. Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract H23G-1717.
Walker, C.W., and H. Lin. 2006. Hydropedology in action: Soil changes after 40 years of wastewater irrigation. 18th World Congress of Soil Science, Philadelphia, Pennsylvania.
Zhou, X., H. Lin, C.W. Walker, and Q. Zhu. 2006. A hydropedologic study of subsurface water flow in a forested catchment. 18th World Congress of Soil Science, Philadelphia, Pennsylvania.
Lin, H., Q. Zhu, C.W. Walker, and X. Zhou. 2006. Precision soil mapping for identifying hydropedologic functional units over an agricultural landscape. International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Indianapolis, Indiana.
Walker, C.W., and H. Lin. 2004. Is the tension delivered by a tension infiltrometer what we think it is? International Annual Meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Seattle, Washington.
Science and Products
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....
MD-DE-DC WSC Laboratory Capabilities
The labs at the MD-DE-DC WSC are clean, well-stocked, and appointed with modern equipment and a highly talented staff. The three labs analyze samples, conduct controlled-environment chemical tests with GCMS in the Water Qualty lab. Scientists and technicians work with core samples and analyze soils in the Sediment Lab.
Our labs assure reliability, reproducibility, and high quality of...
MD-DE-DC WSC Water Quality Capabilities
Water quality is a measure of the suitability of water for a particular use based on selected physical, chemical, and biological characteristics. Water-quality monitoring is used to help water-resource managers understand and avert potential negative effects of man-made and natural stresses on water resources, evaluate trends, and compare to water-quality criteria.
One of our primary...
MD-DE-DC WSC Capabilities Sites
There's a lot of talent at the Maryland, Delaware, Washington, DC Water Science Center!
We’ve created a series of websites, thematically named to characterize our work as our “Capabilities”, working interdependently with a diverse array of cooperative partners, the scientists, technicians, and support staff work tirelessly to produce the high-quality output for which...