Modeling Workgroup Publications

Showing 1 - 76 of 76 publications

Simulation of benthic microalgae impacts on water quality in shallow water systems, Corsica River, Chesapeake Bay

Publication date:

Tian, R., Cai, X., Cerco, C.F., Zhang, J.Y., and Linker, L.C., 2024. "Simulation of benthic microalgae impacts on water quality in shallow water systems, Corsica River, Chesapeake Bay." Frontiers in Marine Science. Volume 10 - 2023. 10:1295986. https://doi.org/10.3389/fmars.2023.1295986.

View document [PDF, 9.7 MB] Simulation of benthic microalgae impacts on water quality in shallow water systems, Corsica River, Chesapeake Bay

The Roles of Tidal Marshes in the Estuarine Biochemical Processes: A Numerical Modeling Study

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Cai, X., Shen, J., Zhang, Y. J., Qin, Q., & Linker, L. (2023). "The roles of tidal marshes in the estuarine biochemical processes: A numerical modeling study." Journal of Geophysical Research: Biogeosciences, 128, e2022JG007066. https://doi.org/10.1029/2022JG...

View document [PDF, 4.2 MB] The Roles of Tidal Marshes in the Estuarine Biochemical Processes: A Numerical Modeling Study

Simulating climate change in a coastal watershed with an integrated suite of airshed, watershed, and estuary models

Publication date:

Linker, L.C., Shenk, G.W., Bhatt, G., Tian, R., Cerco, C.F., and Bertani, I. 2023. “Simulating climate change in a coastal watershed with an integrated suite of airshed, watershed, and estuary models.” JAWRA Journal of the American Water Resources Association 00 (0): 1–30. https://doi.org/10.1111/1752-1688.13185.

View document [PDF, 27.0 MB] Simulating climate change in a coastal watershed with an integrated suite of airshed, watershed, and estuary models

The Chesapeake Bay Land Change Model: Simulating future land use scenarios and potential impacts on water quality

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Claggett, P.R., Ahmed, L., Irani, F.M., McDonald, S., Thompson, R.L. 2023. "The Chesapeake Bay Land Change Model: Simulating future land use scenarios and potential impacts on water quality." Journal of the American Water Resources Association 59 (6): 1287–1312. https://doi.org/10.1111/1752-1688.13131.

View document [PDF, 15.4 MB] The Chesapeake Bay Land Change Model: Simulating future land use scenarios and potential impacts on water quality

Water quality impacts of climate change, land use, and population growth in the Chesapeake Bay watershed

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Bhatt, G., Linker, L., Shenk, G., Bertani, I., Tian, R., Rigelman, J., Hinson, K., and Claggett, P. 2023. “Water quality impacts of climate change, land use, and population growth in the Chesapeake Bay watershed.” JAWRA Journal of the American Water Resources Association 59 (6): 1313–1341. https://doi.org/10.1111/1752-1688.13144.

View document [PDF, 20.6 MB] Water quality impacts of climate change, land use, and population growth in the Chesapeake Bay watershed

Interactions of warming and altered nutrient load timing on the phenology of oxygen dynamics in Chesapeake Bay

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Basenback, N., Testa, J.M., Shen, C. 2023. "Interactions of warming and altered nutrient load timing on the phenology of oxygen dynamics in Chesapeake Bay." Journal of the American Water Resources Association 59 (2): 429–445. https://doi.org/10.1111/1752-1688.13101

View document [PDF, 13.7 MB] Interactions of warming and altered nutrient load timing on the phenology of oxygen dynamics in Chesapeake Bay

Quantifying the Response of Nitrogen Speciation to Hydrology in the Chesapeake Bay Watershed Using a Multilevel Modeling Approach

Publication date:

Bertani, I., G. Bhatt, G.W. Shenk, and L.C. Linker. 2022. "Quantifying the Response of Nitrogen Speciation to Hydrology in the Chesapeake Bay Watershed Using a Multilevel Modeling Approach." Journal of the American Water Resources Association 58 (6): 792–804. https://doi.org/10.1111/1752-1...

View document [PDF, 1.3 MB] Quantifying the Response of Nitrogen Speciation to Hydrology in the Chesapeake Bay Watershed Using a Multilevel Modeling Approach

Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay

Publication date:

Tian, R., C.F. Cerco, G. Bhatt, L.C. Linker, and G.W. Shenk. 2022. "Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay." Journal of the American Water Resources Association 58 (6): 855–875. https://doi.org/10.1111/1752-1....

View document [PDF, 3.8 MB] Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay

Modeling Impacts of Nutrient Loading, Warming, and Boundary Exchanges on Hypoxia and Metabolism in a Shallow Estuarine Ecosystem

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Testa, J.M., N. Basenback, C. Shen, K. Cole, A. Moore, C. Hodgkins, and D.C. Brady. 2022. "Modeling Impacts of Nutrient Loading, Warming, and Boundary Exchanges on Hypoxia and Metabolism in a Shallow Estuarine Ecosystem." Journal of the American Water Resources Association 58 (6): 876–897. https://doi.org/10.1111/1752-1....

View document [PDF, 6.4 MB] Modeling Impacts of Nutrient Loading, Warming, and Boundary Exchanges on Hypoxia and Metabolism in a Shallow Estuarine Ecosystem

A Numerical Study of Hypoxia in Chesapeake Bay Using an Unstructured Grid Model: Validation and Sensitivity to Bathymetry Representation

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Cai, X., Y.J. Zhang, J. Shen, H. Wang, Z. Wang, Q. Qin, and F. Ye. 2022. "A Numerical Study of Hypoxia in Chesapeake Bay Using an Unstructured Grid Model: Validation and Sensitivity to Bathymetry Representation." Journal of the American Water Resources Association 58 (6): 898–921. https://doi.org/10.1111/1752-1...

View document [PDF, 15.5 MB] A Numerical Study of Hypoxia in Chesapeake Bay Using an Unstructured Grid Model: Validation and Sensitivity to Bathymetry Representation

Impacts of Sea-Level Rise on Hypoxia and Phytoplankton Production in Chesapeake Bay: Model Prediction and Assessment

Publication date:

Cai, X., J. Shen, Y.J. Zhang, Q. Qin, Z. Wang, and H. Wang. 2022. "Impacts of Sea-Level Rise on Hypoxia and Phytoplankton Production in Chesapeake Bay: Model Prediction and Assessment." Journal of the American Water Resources Association 58 (6): 922–939. https://doi.org/10.1111/1752-1....

View document [PDF, 3.3 MB] Impacts of Sea-Level Rise on Hypoxia and Phytoplankton Production in Chesapeake Bay: Model Prediction and Assessment

Technical Advisory Committee on Simulating Living Resources in the Long Island Sound Integrated Model - Final Report

Publication date:

In 2020, New York City Department of Environmental Protection (DEP) initiated a project to develop an updated comprehensive hydrodynamic and water quality model for Long Island (LIS). The DEP Long Island Sound Hydrodynamic and Water Quality Modeling Support project (LIS-HWQMS) includes the development of updated hydrodynamic and water quality models (HWQMS) of LI Sound. The LIS-HWQMS provides the physical and biogeochemical components of the overall Integrated Model Framework (IMF) to ensure that physical, biogeochemical, and living resource sub-models provide science-based representations of how these sub-models drive circulation and mixing, biogeochemical interactions that control dissolved oxygen (especially the onset and persistence of hypoxia), nutrient cycling, eutrophication, water clarity, ecological processes and living resources in estuarine and coastal waters.

View document [PDF, 3.5 MB] Technical Advisory Committee on Simulating Living Resources in the Long Island Sound Integrated Model - Final Report

Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

Publication date:

Tian R, Cai X, Testa JM, Brady DC, Cerco CF and Linker LC (2022) Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay. Front. Mar. Sci. 9:1058839. doi: 10.3389/fmars.2022.1058839

View document [PDF, 7.9 MB] Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

Nutrient limitation of phytoplankton in three tributaries of Chesapeake Bay: Detecting responses following nutrient reductions

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Zhang, Q., Fisher, T.R., Buchanan, C., Gustafson, A.B., Karrh, R.R., Murphy, R.R., Testa, J.M., Tian, R., Tango, P.J. Nutrient limitation of phytoplankton in three tributaries of Chesapeake Bay: Detecting responses following nutrient reductions. Water Research, Volume 226, 2022, 119099, ISSN 0043-1354, https://doi.org/10.1016/j.watr....

View document [PDF, 5.4 MB] Nutrient limitation of phytoplankton in three tributaries of Chesapeake Bay: Detecting responses following nutrient reductions

Using Forward and Backward Particle Tracking Approaches to Analyze Impacts of a Water Intake on Ichthyoplankton Mortality in the Appomattox River

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Qin, Q., Shen, J., Tuckey, T.D., Cai, X., Xiong, J. Using Forward and Backward Particle Tracking Approaches to Analyze Impacts of a Water Intake on Ichthyoplankton Mortality in the Appomattox River. Journal of Marine Science and Engineering. 2022; 10(9):1299. https://doi.org/10.3390/jmse10...

View document [PDF, 3.8 MB] Using Forward and Backward Particle Tracking Approaches to Analyze Impacts of a Water Intake on Ichthyoplankton Mortality in the Appomattox River

Atmospheric nitrogen deposition in the Chesapeake Bay watershed: A history of change

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Douglas A. Burns, Gopal Bhatt, Lewis C. Linker, Jesse O. Bash, Paul D. Capel, Gary W. Shenk, Atmospheric nitrogen deposition in the Chesapeake Bay watershed: A history of change, Atmospheric Environment, Volume 251, 2021, 118277, ISSN 1352-2310, https://doi.org/10.1016/j.atmosenv.2021.118277.

View document [PDF, 1.6 MB] Atmospheric nitrogen deposition in the Chesapeake Bay watershed: A history of change

Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay

Publication date:

Tian, R., C.F. Cerco, G. Bhatt, L.C. Linker, and G.W. Shenk. 2021. "Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay." Journal of the American Water Resources Association 1–21. https://doi.org/10.1111/1752-1.... 12907.

View document [PDF, 3.7 MB] Mechanisms Controlling Climate Warming Impact on the Occurrence of Hypoxia in Chesapeake Bay

Projections of Atmospheric Nitrogen Deposition to the Chesapeake Bay Watershed

Publication date:

Campbell, P. C., Bash, J. O., Nolte, C. G., Spero, T. L., Cooter, E. J., Hinson, K., & Linker, L. C. (2019). Projections of Atmospheric Nitrogen Deposition to the Chesapeake Bay Watershed. Journal of Geophysical Research: Biogeosciences, 124. https://doi.org/ 10.1029/2019JG005203.

View document [PDF, 8.6 MB] Projections of Atmospheric Nitrogen Deposition to the Chesapeake Bay Watershed

Factors controlling saltwater intrusion across multi-time scales in estuaries, Chester River, and Chesapeake Bay

Publication date:

Tian, R. Factors controlling saltwater intrusion across multi-time scales in estuaries, Chester River, Chesapeake Bay. Estuarine, Coastal and Shelf Science. Volume 223, 2019, Pages 61-73, https://doi.org/10.1016/j.ecss....

View document [PDF, 3.4 MB] Factors controlling saltwater intrusion across multi-time scales in estuaries, Chester River, and Chesapeake Bay

Assessing Water Quality of the Chesapeake Bay by the Impact of Sea Level Rise and Warming

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P. Wang, L. Linker, H. Wang, G. Bhatt, G. Yactayo, K. Hinson and R. Tian, "Assessing water quality of the Chesapeake Bay by the impact of sea level rise and warming." 2017 IOP Conf. Ser.: Earth Environ. Sci. 82 012001 https://doi.org/10.1088/1755-1315/82/1/012001.

View document [PDF, 1.6 MB] Assessing Water Quality of the Chesapeake Bay by the Impact of Sea Level Rise and Warming

Influence of Wind Strength and Duration on Relative Hypoxia Reductions, Wang P et al 2016

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Wang P, Wang H, Linker L, Hinson K. Influence of Wind Strength and Duration on Relative Hypoxia Reductions by Opposite Wind Directions in an Estuary with an Asymmetric Channel. Journal of Marine Science and Engineering. 2016; 4(3):62. https://doi.org/10.3390/jmse4030062

View document [PDF, 5.7 MB] Influence of Wind Strength and Duration on Relative Hypoxia Reductions, Wang P et al 2016

Geographically Isolated Loading Scenarios to Analyze N and P Exchanges and Explore Nutrient Controls

Publication date: Not listed

Wang, P., Linker, L.C. & Shenk, G.W. Using Geographically Isolated Loading Scenarios to Analyze Nitrogen and Phosphorus Exchanges and Explore Tailored Nutrient Control Strategies for Efficient Management. Environ Model Assess 21, 437–454 (2016). https://doi.org/10.1007/s10666-015-9487-x.

View document [PDF, 1.9 MB] Geographically Isolated Loading Scenarios to Analyze N and P Exchanges and Explore Nutrient Controls

Calculation of Oyster Benefits with a Bioenergetics Model of the Virginia Oyster - April Draft

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A bioenergetics model is formulated and validated for the Virginia oyster (Crassostrea virginica). The model considers two basic properties of a bivalve population: number of individuals and individual size. Individuals are represented as three energy stores: soft tissue, shell, and reproductive material. The bioenergetics model is coupled to an oyster benefits module. Calculated benefits include various aspects of carbon removal, nitrogen removal, phosphorus removal, solids removal, and shell production. Benefits are calculated for natural mortality and for fisheries harvest. The calculation of benefits is based on mass-balance principles and upon user-supplied values for parameters including resuspension, sediment diagenesis, and dentrification rate. The bioenergetics model is coupled with a representation of the physical environment based on the tidal prism approach and with eutrophication kinetics from the CE-QUAL-ICM model.

View document [PDF, 2.2 MB] Calculation of Oyster Benefits with a Bioenergetics Model of the Virginia Oyster - April Draft

Evaluation: Three-Dimensional Hydrodynamic Model Through Long-Term Simulation of Transport Processes

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Kim, Sung-Chan, 2013. Evaluation of a Three-Dimensional Hydrodynamic Model Applied to Chesapeake Bay Through Long-Term Simulation of Transport Processes. Journal of the American Water Resources Association (JAWRA) 1-13. DOI: 10.1111/jawr.12113

View document [PDF, 3.1 MB] Evaluation: Three-Dimensional Hydrodynamic Model Through Long-Term Simulation of Transport Processes

Computing Atmospheric Nutrient Loads to the Chesapeake Bay Watershed and Tidal Waters

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Linker, Lewis C., Robin Dennis, Gary W. Shenk, Richard A. Batiuk, Jeffrey Grimm, and Ping Wang, 2013. Computing Atmospheric Nutrient Loads to the Chesapeake Bay Watershed and Tidal Waters. Journal of the American Water Resources Association (JAWRA) 1-17. DOI: 10.1111/jawr.12112

View document [PDF, 1.6 MB] Computing Atmospheric Nutrient Loads to the Chesapeake Bay Watershed and Tidal Waters

Modeling the pH in the tidal fresh Potomac River under conditions of varying hydrology and loads

Publication date: Not listed

Carl F. Cerco, Tammy Threadgill, Mark R. Noel, Scott Hinz, Modeling the pH in the tidal fresh Potomac River under conditions of varying hydrology and loads, Ecological Modelling, Volume 257, 2013, Pages 101-112, ISSN 0304-3800, https://doi.org/10.1016/j.ecolmodel.2013.02.011.

View document [PDF, 1.0 MB] Modeling the pH in the tidal fresh Potomac River under conditions of varying hydrology and loads

Integration of a fish bioenergetics model into a spatially explicit water quality model

Publication date: Not listed

P. Soupy Dalyander, Carl F. Cerco, Integration of a fish bioenergetics model into a spatially explicit water quality model: Application to menhaden in Chesapeake Bay, Ecological Modelling, Volume 221, Issue 16, 2010, Pages 1922-1933, ISSN 0304-3800, https://doi.org/10.1016/j.ecolmodel.2010.05.002.

View document [PDF, 826.0 KB] Integration of a fish bioenergetics model into a spatially explicit water quality model

Documentation for Scenario Builder

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Creation of the Nutrient and Scenario Builder tool was achieved with the excellent assistance of the Chesapeake Bay Program Information Technology contractor’s team led by Jessica Rigelman. With her leadership, Jonathan Lewis, Robert Weiss, Mark Lane, and Aaron Knister built a complex functional software product under a very tight deadline. Their questions along the way helped to strengthen the methodology. Without Jessica Rigelman’s encouragement of all of us, this project would not have been accomplished.

View document [PDF, 3.1 MB] Documentation for Scenario Builder

Watershed Model Phase 4.3 Calibration Rules

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The Chesapeake Bay Watershed Model (WSM) has been in continuous operation at the Chesapeake Bay Program since 1982, and has had many upgrades and refinements since that time. The WSM described in this paper is application Phase 4.3, based on the Hydrologic simulation Program - Fortran (HSPF) Version 11 Bicknell, et al., 1996). HSPF is a widely used public domain model supported by the EPA, USGS and Corps of Engineers.

View document [PDF] Watershed Model Phase 4.3 Calibration Rules

The 2002 Chesapeake Bay Eutrophication Model

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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. Nutrient and solids loads are computed on a daily basis for 94 sub-watersheds of the Chesapeake Bay watershed. The CH3D-WES hydrodynamic model computes three-dimensional intra-tidal transport on a grid of 13,000 cells. 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. The eutrophication model incorporates a predictive sediment diagenesis component. Ten years, 1985-1994 are simulated continuously using time steps of 5 minutes (hydrodynamic model) and 15 minutes (eutrophication model). This report comprises the primary documentation of the eutrophication component of the 2002 CBEMP.

View document [PDF] The 2002 Chesapeake Bay Eutrophication Model

Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability

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The TSD was developed by the EPA and its watershed partners to be a companion document to the Regional Criteria Guidance. Because it describes the development and geographical extent of the designated uses to which the refined water quality criteria may apply, the TSD serves as a resource to the states to assist them in the development and adoption of refined water quality standards.

View document [PDF] Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability

Review of the Benthic Process Model with Recommendations for Future Modeling Efforts

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The Benthic Process Model Review Team, assembled by the Modeling Subcommittee during Fall 2000, reviewed the benthic model developed for the Chesapeake Bay Water Quality Model, a component of Chesapeake Bay Estuary Modeling Package. Review of the model presented in the technical, report, Development of a Suspension Feeding and Deposit Feeding Benthos Model for Chesapeake Bay (USCE 0410) was guided by questions provided by the Modeling Subcommittee. The Review Team was further charged with advising the Modeling Subcommittee regarding the future directions in benthic process modeling that will be needed in order to satisfy the goals and objectives stated in the Chesapeake 2000 Agreement.

View document [PDF] Review of the Benthic Process Model with Recommendations for Future Modeling Efforts

A Comparison of Chesapeake Bay Estuary Model Calibration with 1985-1994 Observed Data and Method of

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In this report, observations of dissolved oxygen concentrations, chlorophyll concentrations, and light attenuation are compared to model estimates taken at the same time and location in model space. The comparison includes scatter plots, cumulative plats, regressions, and summary statistics. The method of adapting the model for application to the proposed water quality criteria through the use of regressions, spatial interpolation, and cumulative frequency plots of criteria exceedences is described.

View document [PDF] A Comparison of Chesapeake Bay Estuary Model Calibration with 1985-1994 Observed Data and Method of

The 2010 Chesapeake Bay Eutrophication Model

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The Chesapeake Bay Environmental Model Package is a combination of interactive models. The Community Multi-Scale Air Quality Model and a set of regression models compute daily atmospheric nitrogen and phosphorus loads to the Chesapeake Bay watershed and to the water surface. The Watershed Model (WSM) provides daily computations of flow, solids loads, and nutrient loads at the heads of major tributaries and along the shoreline below the tributary inputs. Flows from the WSM are one set of inputs to the CH3D (Computational Hydrodynamics in Three Dimensions) hydrodynamic model. CH3D computes surface level, three-dimensional velocities, and vertical diffusion on a time scale measured in minutes. Loads from the WSM and transport processes from CH3D drive the CE-QUAL-ICM (Corps of Engineers Integrated Compartment Water Quality Model) eutrophication model. ICM computes, in three dimensions, physical properties, algal production, and elements of the aquatic carbon, nitrogen, phosphorus, silica, and oxygen cycles.

View document [PDF] The 2010 Chesapeake Bay Eutrophication Model

Tributary Refinements to the Chesapeake Bay Model

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A series of refinements were added to a previously-completed three-dimensional eutrophication model of Chesapeake Bay. Refinements included increased grid resolution in the western tributaries and in shallow littoral areas, extension of the grid onto the continental shelf, extension of the validation period to 1985-1994, and addition of living resources. Computations of zooplankton, submerged aquatic vegetation, and benthos compared successfully with observations aggregated over annual time scales and at spatial scales on the order of 100 km2.

View document [PDF, 5.8 MB] Tributary Refinements to the Chesapeake Bay Model

Assessing a Ten-Fold Increase in the Chesapeake Bay Native Oyster Population

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The Chesapeake Bay Environmental Model Package (CBEMP) was used to assess the environmental benefits of a ten-fold increase in native oysters in Chesapeake Bay. The CBEMP consists of a coupled system of models including a three-dimensional hydrodynamic model, a three-dimensional eutrophication model, and a sediment diagenesis model. The existing CBEMP benthos submodel was modified to specifically represent the Virginia oyster, Crassostrea virginica. The ten-fold oyster restoration is computed to increase summer-average, bottom, dissolved oxygen in the deep waters of the bay (depth > 12.9 m) by 0.25 g m-3. Summer-average system-wide surface chlorophyll declines by 1 mg m-3. Filtration of phytoplankton from the water column produces net removal of 30,000 kg d-1 nitrogen through sediment denitrification and sediment retention. A significant benefit of oyster restoration is enhancement of submerged aquatic vegetation. Calculated summer-average biomass improves by 25% for a ten-fold increase in oyster biomass. Oyster restoration is most beneficial in shallow regions with limited exchange rather than in regions of great depth, large volume and spatial extent.

View document [PDF] Assessing a Ten-Fold Increase in the Chesapeake Bay Native Oyster Population

Evaluating Ecosystem Effects of Oyster Restoration in Chesapeake Bay-A report to the MD DNR

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The Chesapeake Bay Environmental Model Package (CBEMP) was used to assess the environmental benefits of oyster restoration in Chesapeake Bay. The CBEMP consists of a coupled system of models including a three-dimensional hydrodynamic model, a three-dimensional eutrophication model and a sediment diagenesis model

View document [PDF] Evaluating Ecosystem Effects of Oyster Restoration in Chesapeake Bay-A report to the MD DNR

Setting and Allocating the Chesapeake Bay Basin Nutrient and Sediment Loads: The Collaborative Proce

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The Chesapeake 2000 agreement has been guiding Maryland, Pennsylvania, Virginia and the District of Columbia, the Chesapeake Bay Commission and the U.S. Environmental Protection Agency (EPA) in their combined efforts to restore and protect the Chesapeake Bay. It defined the goal to achieve and maintain the water quality necessary to support the aquatic living resources of the Bay and its tributaries and to protect human health. Subsequently, Delaware, New York and West Virginia signed a Memorandum of Understanding committing to implement the Water Quality Protection and Restoration section of the agreement.

View document [PDF] Setting and Allocating the Chesapeake Bay Basin Nutrient and Sediment Loads: The Collaborative Proce

Technical Tools Used in the Development of Virginia's Tributary Strategies: A Synthesis of Airshed,

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The overall modeling framework used to assess Virginia's tributary strategies in 1999 is documented. This synthesis report provides an overview of the Chesapeake Bay Program airshed, watershed, and estuary models and other diagnostic tools which were applied to determine tributary allocations for each of the four lower Virginia basins; the Rappahannock, York, Hames, and Easter Shore Virginia. The publication describes the model scenarios developed to test various management options aimed at improving water and bay grasses quality through different levels of nutrient and sediment reductions. Tracer analyses are presented to better understand the hydrologic interactions among tributaries and the mainstem Bay. Watershed and estuarine physical descriptions, flows and nutrient and sediment loadings of the lower Chesapeake Bay system are detailed. As responses to these loadings, modeled measures of water and habitat quality, needed to sustain key living resources, are interpreted and address.

View document [PDF] Technical Tools Used in the Development of Virginia's Tributary Strategies: A Synthesis of Airshed,

Review of Phase 5 Watershed Model Hydrologic Calibration

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The hydrologic calibration of the phase 5 watershed model was evaluated through 9 published acceptable criteria used in HSPF Expert system. The specific flow characteristics evaluated are: Error in total volume; Error in low flow or base flow recession; Error in 50% lowest flow; Error in 10% highest flow; Error in storm volumes; Summer volume error; Winter volume error; Summer storm volume error; and Storm peaks simulated verses observed for selected storms in inches. One Phase 5 base flow statistic was also used.

View document [PDF] Review of Phase 5 Watershed Model Hydrologic Calibration

Tidal Sediment Yield Estimate Methodology in Virginia for the Chesapeake Bay Program Water Quality M

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Water quality in Chesapeake Bay has degraded over the past 50 years with respect to oxygen depletion and reduced light attenuation. While the causes are numerous, sediment resuspension from wave and tidal action cloud the water column and reduce light attenuation thereby negatively affecting submerged aquatic vegetation (SAV) beds. Sediments on the Bay bottom come from upland runoff and shoreline erosion, each of which has significant contributions to the loading of sediments into estuary. The purpose of this report is to assess the present methods used to calculate sediment loading from tidal shoreline erosion that is input to the Chesapeake Bay Water Quality Model (WQM).

View document [PDF] Tidal Sediment Yield Estimate Methodology in Virginia for the Chesapeake Bay Program Water Quality M