Billy H. Johnson, Ph.D., P.E., D.WRE
CHT Managing Partner
Dr. Billy Johnson has over 37 years of experience in developing and applying numerical models to address water resources problems. He retired from the US Army Engineer Waterways Experiment Station (WES), after more than 30 years of service, in 2001. During his 30 years at WES, he was involved in developing models such as FLOWSED (1D unsteady river model), LAEMSED (2D laterally-averaged flow and sediment transport), CH3D (curvilinear hydrodynamics in three-dimensions), STFATE (short-term fate of dredged material disposed in open water), and SSFATE (suspended sediment fate of material re-suspended at the dredging site). His expertise in the development and application of advanced numerical modeling tools is reflected through the many awards he received during his federal career. These include WES Engineer of the Year 1989, Mississippi ASCE Hydraulic Engineer of the Year 1990, Department of the Army Research and Development Award 1991, Associate Editor of ASCE Journal of Hydraulic Engineering 1993-97, and the EPA National Science Award in Water Quality Modeling 1999. In 2005, Dr. Johnson was inducted into the WES Gallery of Distinguished Employees and as a Diplomate, Water Resources Engineering in the American Academy of Water Resources Engineers. He is the author of over 100 technical reports, conference proceedings, book chapters, and journal articles.
Allen M. Teeter, Ph.D.
Dr. Allen M. Teeter has over 37 years of experience in developing and applying numerical models to address water resources problems. He retired from the US Army Engineer Waterways Experiment Station (WES) in December 2003. Dr. Teeter is considered one of the leading experts in the world in the physics of cohesive sediments. He has contributed heavily to the basic understanding of how such sediments behave under different hydraulic forcings. He serves on national and international working groups such as ASCE’s Cohesive Sediment Dynamics Task Committee and the International Workshop on Cohesive Sediment Dynamics. Dr. Teeter has published numerous journal articles on his research and has written chapters in books such as Cohesive Sediments and Coastal and Estuarine Fine Sediment Processes. During his federal career he received numerous awards, e.g. EPA Bronze Medal, WES Scientist of the Year 1990, and Mississippi ASCE Hydraulics Award 2002. Results from Dr. Teeter’s research on cohesive sediments have been implemented in many numerical sediment transport models. Examples include a model (SSFATE) to predict suspended sediment concentrations at dredging sites, a model called COSED that predicts sediment erosion from dredged material disposal mounds, and generalized two- and three-dimensional hydrodynamic / sediment transport models (TABS-MD and SED2D).
Norman W. Scheffner, Ph.D., P.E.
Dr. Norman Scheffner has over 37 years of experience in developing and applying innovative approaches for addressing various types of water resource problems. He retired from the US Army Engineer Waterways Experiment Station (WES) in December 2003. During his more than 30 years of federal service at WES, he was involved in the development and application of both physical and numerical models to provide support for a wide variety of Corps of Engineers projects and research programs. He developed a constituent based approach for physical model verification, developed a methodology for simulating storm-associated coastal dune erosion, was the developer of the LTFATE (Long-Term FATE) dredged disposal site stability model, was co-developer of the ADCIRC (Advanced CIRCulation) long-wave hydrodynamic model, and co-developer of the EST (Empirical Simulation Technique) statistical approach to life-cycle simulations to compute damage-frequency relationships. He introduced the concept of large domain storm surge and tidal circulation modeling in support of the Corps' large coastal design program. Dr. Scheffner received the 1993 U.S. Army Engineer Waterways Experiment Station Director's Research and Development Award and the 1993 Department of the Army Research and Development Achievement Award for his research efforts. He is a former US Army officer; a member of ASCE; and the author of over 100 technical reports, conference proceedings, book chapters, and journal articles.
Michael J. Trawle, P.E.
Michael Trawle has over 39 years of experience in solving water resources problems. He retired in 1997 after 28 years of federal service. During the early years of his career at WES, he was involved in conducting physical model studies of estuaries. With the introduction of numerical estuarine models in the late 1970’s – early 1980’s, he moved into conducting large-scale numerical models of estuarine and sediment transport using the RMA finite-element models developed through WES funding. The last 10 years of his career were spent as the Chief of the Rivers Branch. In that position, he was actively involved in numerical modeling studies involving river and stream hydrodynamics and sediment transport using models such as HEC-6. Since 1997, he has remained active in the numerical modeling arena through his participation in a 3D sediment diversion study at the Old River Control Structure on the Lower Mississippi River and through working with the Vicksburg and New Orleans Districts of the Corps of Engineers on many watershed / stream studies using models such as HEC-RAS, HEC-HMS, and HEC-6. He is the author of over 50 technical reports, journal articles, etc.
Thomas J. Pokrefke, Jr., P.E.
Tom Pokrefke has over 40 years of experience in river engineering and sedimentation, fluvial geomorphology, and navigation and environmental related studies. He retired from the US Army Engineer Waterways Experiment Station (WES) in 2004 after 36 years of federal service. He conducted various hydraulic studies using both fixed-bed and movable-bed models. These include studies on major US rivers and on smaller navigable rivers. The studies conducted included developing dike systems to improve navigation, alignment of locks and dams for navigation, improvement of flood-control structures, and providing technical assistance to various Corps offices for the solution of sedimentation problems and hydropower plant retrofits at Corps projects. His international experience includes the layout and design of river training structures on the Han River in the Republic of Korea and for the Jamuna River Bridge in Bangladesh. Using a physical, movable-bed model, he developed and implemented the innovative method of river training known as bendway weirs, which have been widely applied on the Mississippi River. He received the 1992 Department of the Army Engineer Research and Development Achievement Award for his bendway weir research. He was the leader of a multi-disciplinary team responsible for a study to address the cumulative impacts on erosion as a result of proposed changes to the operation of the main stem dams on the Missouri River and lead a team to determine impacts of present and future towboat navigation traffic on all of the backwaters and secondary channels on the Mississippi River and the Illinois Waterway. He was the 1995 Mississippi ASCE Hydraulic Engineer of the Year and received the Department of the Army Meritorious Civilian Service Award and the Corps of Engineers silver de Fleury Medal. In 2005, Mr. Pokrefke received the ASCE Hans Albert Einstein Award for his contributions to the science of fixed- and movable- bed modeling and in the application of his expertise in hydraulic and sediment transport processes.
James L. Martin, Ph.D., P.E., D.WRE, F.ASCE
Dr. Martin has over 33 years of experience in conducting and managing water quality modeling projects. He conducted studies while a Research Civil Engineer with the Water Quality and Contaminant Modeling Branch, U.S. Army Corps of Engineers Waterways Experiment Station (WES), while Vice President and Director of Engineering with ASCI Corporation, and while a Research Environmental Scientist with the U.S. Environmental Protection Agency (EPA) at its Large Lakes Research Station. For five years he provided contract support to the EPA's Center for Exposure Assessment Modeling through model development, providing technical assistance to the EPA, state and local agencies, and through model application. Dr. Martin currently holds the Kelly Gene Cook Chair in Civil Engineering at Mississippi State University. He has received numerous awards, including the 2004 Mississippi ASCE Hydraulic Achievement Award. He has authored/co-authored over 50 technical reports and publications, including EPA guidance documents and model user documentation. He is presently Chairman of the ASCE Energy Division Executive Committee and a former editor of, ASCE Journal of Energy Engineering. He is certified as a Diplomate, Water Resources Engineering by the American Academy of Water Resources Engineers and is a Fellow of the ASCE. He has been involved in the development of a number of hydrodynamic and water quality models in common usage and is senior author of the textbook Hydrodynamics and Transport for Water Quality Modeling. Dr. Martin has particular expertise in the area of Water Quality Modeling and Environmental Software Development.
Mark S. Dortch, Ph.D., P.E., D.WRE, F.ASCE
Dr. Dortch has over 36 years of experience that have covered diverse specialties, including hydraulic modeling, reservoir water quality enhancement techniques, reservoir selective withdrawal mechanics, computational hydraulics, systems analysis, water quality modeling, contaminant transport/fate modeling, and health risk assessment modeling. He led the development of the CE-QUAL models for water quality, including the RI, RIV1, W2, ICM, and ICM/TOXI models. He was also a co-developer of models for reservoir tail-water quality (TWQM), wetland pollutant removal (PREWet), contaminant fate in sediments (RECOVERY), contaminant transport/fate in streams (CMS), and human and ecological health risk assessment (ARAMS). He led the water quality team that developed a three-dimensional water quality model of Chesapeake Bay for the EPA Bay Program. Dr. Dortch received the Department of the Army R&D Achievement Award 1992, the Herbert D. Vogel Engineer of the Year Award 1991, the Army Meritorious Civil Service Award 1991 and 2002, and the ERDC R&D Achievement Award 2003. He has served as Associate Editor of J. Hydraulic Engineering 1990-1994 and on numerous expert review panels, including panels for Gulf of Mexico nutrient enrichment and hypoxia, Jamaica Bay, Biscayne Bay, Florida Keys carrying capacity, South Florida modeling and ecosystem restoration, and Federal Interagency Steering Committee for Multimedia Environmental Modeling (Chair 2003). Dr. Dortch is the author of over 130 technical reports, conference proceedings, book chapters, and journal articles.
Billy E. Johnson, Ph.D., P.E., D.WRE
Dr. Billy E. Johnson has over 23 years experience in developing and applying riverine and watershed models to address water resources problems across the United States. He has worked for the US Army Corps of Engineers Mississippi Valley Division (MVD) and the Memphis District and is currently employed at the Engineer Research and Development Center (ERDC). Dr. Johnson has also worked in the private sector for Concurrent Technologies Corporation, located in Bremerton, WA. Dr. Johnson has applied a variety of numerical models, with CH3D, HEC-1, HEC-2, HEC-HMS, HEC-RAS, CE-QUAL-W2, HSPF, CASC2D, and GSSHA being among the more prominent ones. He is an expert in the use of GIS in numerical modeling. Dr. Johnson is currently involved in the development of a state-of-the-art distributed watershed water quality model. This model, CASC2D/GSSHA, encompasses the full hydrologic cycle in addition to eroding, depositing, and transporting sediments, nutrients, and contaminants (including heavy metals) on a cell by cell basis to the watershed outlet. Dr. Johnson is currently the working group leader for an Interagency Working Group tasked with finding ways for various federal agencies to collaborate in the development of distributed watershed water quality models. Dr. Johnson is an active member of the American Society of Civil Engineers (ASCE), the American Water Resources Association (AWRA), and the International Association of Hydrological Sciences (IAHS). In addition, Dr. Johnson is an adjunct faculty member in the Department of Civil Engineering at Mississippi State University. In this role, Dr. Johnson has developed and teaches "Engineering Hydrology" at the Waterways Experiment Station Graduate Center, located in Vicksburg, MS. He is the author of over 50 technical reports, conference proceedings and journal articles.
Zhonglong Zhang, Ph.D., P.E., P.H.
Dr. Zhang has over 20 years of experience working in the water resources and water quality fields, which include the development of sophisticated modeling tools to understand the hydrologic cycle and its effects on water quality. Currently he is involved in developing cutting-edge watershed water quality and contaminant transport models, which are being integrated with a variety of USACE hydraulic and hydrologic models (water engines). He has applied HEC-HMS/RAS, HSPF, AnnAGNPS, SWAT, MIKE-SHE/11, SWMM, QUAL2E, WASP, CE-QUAL-W2/ICM, MODFLOW and MT3D models and performed modeling setup, calibration, validation and scenario analysis, including collection of information and data to support watershed, TMDL and ecosystem restoration studies. He is experienced with GIS and emerging information technology in water resources and environmental assessment. He is an adjunct faculty member of the Department of Civil and Enviromental Engineering at both Mississippi State University and Jackson State University. With these appointments, he has taught both graduate and undergraduate courses. Dr. Zhange is a registered professional engineer in the State of Washington and a registered professional hydrologist in the American Institute of Hydrology. He is an active member in the ASABE, AGU, AWRA, AIH, IAHR, and IAHS. He is the author of over 30 technical reports, conference proceedings, book chapters, and journal articles.
Malcolm L. Dove, P.E.
Mr. Dove was employed by the U.S. Army Corps of Engineers as a hydraulic engineer for over 32 years. He was involved in the planning, design and technical review of a varied range of hydrologic studies and hydraulic design of flood control and inland waterway navigation projects. He has used microcomputers and related engineering software to accomplish his work. As a staff hydraulic engineer with the Mississippi Valley Division (MVD) he was responsible for the technical review of large flood control and navigation projects, which included the hydraulic and hydrology studies as well as determining the relationship between the hydrologic effects and economic impact of the projects. Mr. Dove has used several different numerical modes to aid in accomplishing the technical review of hydrologic studies. Since retirement from teh U.S. Army Corps of Engineers he has worked as an independent hydraulic engineer on several studies involving hydrologic planning and design of all types of flood control projects, including reservoir studies, navigation channels and dams, channel improvement studies, interior basin flood protection studies, and hydrologic environmental planning studies.
Computational Hydraulics and Transport LLC. 2006.