Region 3 – Lessons Learned from Chesapeake Bay Eutrophication and Ecosystem Modeling
	This seminar will use a "case study" approach to highlight lessons learned over the 20+ years of modeling experience in the Chesapeake Bay Region. Case studies will describe: 1) water quality problems in the context of the TMDL program, 2) modeling solutions as well as any associated research, and monitoring, to address the problem, and 3) the resolution/decision that the model supported. Featured Speakers include: Lewis Linker and Gary Shenk from the Chesapeake Bay Program Office (Region 3), Carl Cerco from US Army Engineer Research and Development Center, and James Hagy from EPA‘s NHEERL (ORD) Research Laboratory PowerPoint slides will be available by June 18, 2004 – email Elsie Sunderland (Sunderland.Elsie@epa.gov) if you would like to have these sent to you directly before the presentation.
Agenda
100-110		Welcome & Introduction to Regional Seminar Series Gary J. Foley, CREM Co-Chair
110-115		Regional Modeling Overview Lewis C. Linker, Modeling Coordinator, Chesapeake Bay Program Office
115-130		Chesapeake Bay Watershed Model Gary Shenk, Chesapeake Bay Program Office, Region 3
130-135		Questions and Discussion
135-150		Data Adjustment of TMDL Model Estimates Gary Shenk, Chesapeake Bay Program Office, Region 3
150-200		Questions and Discussion
200-220		Modeling of Suspended Solids and Living Resources Interactions Carl F. Cerco, US Army Engineer Research and Development Center
220-230		Questions and Discussion
230-250		A Restoration Scenario for the Summer Food Web of the Middle Chesapeake Bay: An Analysis with Trophic Network Models James D. Hagy III, Gulf Ecology Division, EPA NHEERL Research Laboratory
250-300		Questions and Open Discussion

Presentations
	Chesapeake Bay Watershed Model (PDF 66 pp., 2 MB, info about PDF) The Watershed model divides the 64,000 square mile Chesapeake Bay drainage basin into 94 model segments. Each segment contains information generated by a hydrologic submodel, a nonpoint source submodel, and a river submodel. The hydrologic submodel uses rainfall, evaporation and meteorological data to calculate runoff and subsurface flow for all basin land uses including forest, agricultural and urban lands. The surface and subsurface flows ultimately drive the nonpoint source submodel, which simulates soil erosion and the pollutant loads from the land to the rivers. The river submodel routes flow and associated pollutant loads from the land through lakes, rivers, and reservoirs to the Bay. The Watershed Model is based on the open source, public domain HSPF code. The Watershed Model has been operational and providing information on Chesapeake watershed nutrient and sediment loads for more than two decades.Since 1982, there have been five major upgrades. The latest upgrade is the Phase 5 Community Watershed Model.Phase 5 increases by an order of magnitude the segmentation scale and expands the model structure to simulate more land uses and management practices.The Phase 5 Community Watershed Model is being developed as a community model with all model code, preprocessors, postprocessors, and model input data available to any user from the web.
	Data Adjustment of TMDL Model Estimates (PDF 9 pp., 261 KB, info about PDF) Data adjustment is an approach that can be applied when a comparison of a model estimate with a finite value is the metric that determines achievement of a water quality criterion. This is common in TMDLs where, for example, a dissolved oxygen level of 5 mg/l is to be maintained in surface waters for living resource protection. Model calibrations are often considered “good” when the mean, range, and frequency of the calibration match observations. This is sufficient to provide relative water quality differences among scenarios, but may be insufficient to provide the rigor of an “achieved/not achieved” metric of a finite value criterion. To generate a data adjustment of model estimates for a particular scenario, the frequency distribution output from a scenario is compared with the frequency distribution output of the model calibration. Data is compared on a month-by-month basis. For each point along the frequency distribution of model scenario and calibration data where an observation exists during the 1985–1994 period, a mathematical relationship between the model scenario data and the model calibration data was established by regressing the daily values. The regression generates a unique equation for data from each model cell corresponding to a monitoring station used to develop the observed calibration data. Once the relationship between the model calibration and any particular scenario is established, this relationship is used to generate a ‘scenario-modified’ observed data set for the scenario. The ‘scenario-modified’ values represent an estimate of an observed data set under the conditions of nutrient and sediment management represented by the scenario. Each observed value for dissolved oxygen, chlorophyll a, and light attenuation in the 1985-1994 data set is replaced with a ‘scenario-modified’ value. This approach has several advantages. First, the observed distribution of data is preserved in the scenario estimates as the scenario difference is projected on the observed frequency. Secondly, the strength of the model in quantifying the relative differences in water quality due to different nutrient and sediment loads is also preserved. Finally the scenario estimates project on to the observed data generates a ‘scenario-modified’ observed data set, which can than be used in exactly the same way the observed data is used to estimate the frequency, duration, and magnitude of water quality standard violation through various tools which assess the time and space relationships of criterion achievement/non-achievement.
	Modeling of Suspended Solids and Living Resources Interactions (PDF 31 pp., 1 MB, info about PDF) Deterioration of water quality and associated losses of living resources have been recognized as problems in Chesapeake Bay for more than twenty years. Elimination of anoxia and restoration of submerged aquatic vegetation remain prime management goals. Models have been employed as tools to guide management since the formation of the first water quality targets. Over time, as management focus has been refined, models have been improved to provide appropriate, up-to-date guidance. Three models are at the heart of the Chesapeake Bay Environmental Model Package (CBEMP). Distributed flows and loads from the watershed are computed with a highly modified version of the HSPF model. These flows are input to the CH3D-WES hydrodynamic model, which computes three-dimensional intra-tidal transport. Computed loads and transport are input to the CE-QUAL-ICM eutrophication model which computes algal biomass, nutrient cycling, and dissolved oxygen, as well as numerous additional constituents and processes. Initial application of the CBEMP emphasized computation of chlorophyll concentrations and bottom-water anoxia. As management emphasis shifted to living resources rather than living-resource indicators, the detrimental impact of suspended solids on living resources became more apparent. As a consequence, modeling emphasis is shifting to incorporate suspended solids/living resource interactions. Modeling efforts to date have included suspended solids budgeting, computation of light attenuation, and computation of suspended solids interactions with submerged aquatic vegetation. Much additional work is indicated. Plans call for improved representation of suspended solids transport, for improved estimates of bank loading, and for improved representation of suspended solids/living resource interactions.
	A Restoration Scenario for the Summer Food Web of the Middle Chesapeake Bay: An Analysis with Trophic Network Models (PDF 26 pp., 348 KB, info about PDF) Over the past 50 years, nutrient enrichment of Chesapeake Bay has been associated with increased phytoplankton production, a large increase in hypoxia, degradation of the benthos, and other changes in the food web of the Bay. Restoration efforts center on reducing nutrient inputs and are guided by complex, multimedia eutrophication models, which seek to predict the specific outcomes of management actions. Although these models are demonstrably effective for water quality and lower trophic levels, predictions become more tenuous for upper trophic levels. To better understand the possible trajectory of restoration for upper trophic levels, a scenario for ecosystem restoration was evaluated by constructing and analyzing steady-state trophic network models. A reference model was constructed to characterize the food web of the mesohaline Chesapeake Bay in the 1990's was contrasted with a restored Bay scenario, constructed to represent a less eutrophic Chesapeake Bay, which is less affected by hypoxia. Differences between the current and reference networks were based on historical data, including historical data on DO and biota, currently observed associations between DO and biota in Chesapeake Bay and elsewhere, and mass balance constraints. These models illustrate how a less eutrophic Chesapeake Bay could support fisheries outputs equal to or greater than present levels.
Featured Speakers
	Gary Shenk Chesapeake Bay Program Office 410 Severn Avenue Annapolis, MD 21403 Ph: 410-267-5745 gshenk@chesapeakebay.net Gary Shenk has been with the modeling team at the EPA’s Chesapeake Bay Program Office since 1995. His involvement with watershed modeling includes responsibility for calibration, software design, and communication. His is currently the lead developer of the Phase 5 Community Watershed Model. Before joining the Chesapeake Bay Program Office, Gary completed his Masters in Civil Engineering from University of Virginia.
	Carl F. Cerco, PhD, PE Research Hydrologist Mail Stop EP-W US Army ERDC 3909 Halls Ferry Road Vicksburg MS 39180 USA 601-634-4207 (voice) 601-634-3129 (fax) cercoc@wes.army.mil Dr. Carl F. Cerco is a Research Hydrologist with the US Army Engineer Research and Development Center, Vicksburg MS. He has broad training in engineering and science and has participated in applied research both in modeling and in processes underlying the models. Since commencing the study of water quality in 1972, he has developed and/or applied models of waste heat discharge in lakes, multi-dimensional hydrodynamics of estuaries, eutrophication processes in estuaries, effects of salt marshes on water quality, sediment-water interactions, and living resources. Dr. Cerco is the primary author of the kinetics portion of the CE-QUAL-ICM eutrophication model. Since initial development, the CE-QUAL-ICM model has been applied to diverse environments including estuaries (Chesapeake Bay), coastal lagoons (Delaware Inland Bays), tropical bays (Florida Bay, San Juan Bay Estuary), and lakes (Lake Washington). Dr. Cerco is a licensed professional engineer, is a member of three professional societies, and is a recognized author, reviewer, and editor. He is presently Associate Editor of the Journal of Environmental Engineering and is co-editor of an upcoming special issue on Total Maximum Daily Loads. Prior to his arrival at ERDC, Dr. Cerco was Assistant Professor of Marine Science at the School of Marine Science, College of William and Mary. Dr. Cerco’s publications include technical reports, book chapters, editorials, conference proceedings, and fifteen peer-reviewed professional publications.
	James D. Hagy III, Ph.D. US EPA, NHEERL / Gulf Ecology Division 1 Sabine Island Drive, Gulf Breeze, FL 32561 PH (850) 934-2455, FAX (850) 934-2401 hagy.jim@epa.gov Dr. James D. Hagy III is an ecologist with the Gulf Ecology Division of EPA’s National Health and Environmental Effects Research Laboratory, located in Gulf Breeze, FL. He is broadly trained in estuarine ecology, and has focused his research on understanding eutrophication of coastal waters from an integrative, ecosystem-scale perspective. Dr. Hagy completed his Ph.D. in 2002 at the University of Maryland Center for Environmental Science, where his research focused on Chesapeake Bay. His doctoral dissertation, entitled “Eutrophication, Hypoxia and Trophic Transfer Efficiency in Chesapeake Bay” examined the historical trajectory of hypoxia in Chesapeake Bay, ecosystem processes affecting hypoxia in the Bay, and the likely effects of hypoxia on the Chesapeake Bay food web. His current research examines development of hypoxia in Gulf of Mexico estuaries and in the coastal hypoxic region extending from the plume of the Mississippi and Atchafalaya Rivers.