Final Integrated General Reevaluation Report II and Supplemental
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NAVIGATION STUDY FOR JACKSONVILLE HARBOR, FLORIDA FINAL INTEGRATED GENERAL REEVALUATION REPORT II AND SUPPLEMENTAL ENVIRONMENTAL IMPACT STATEMENT APPENDIX A ATTACHMENT E ENGINEERING – Hydrodynamic Modeling and Field Data Summary Hydrodynamic Modeling and Data Summary Introduction This General Reevaluation Report (GRR) is being prepared to determine the feasibility of deepening and/or widening the federal navigation channel of the Jacksonville Harbor Federal Navigation Project. Project alternatives considered include: deepening of the Federal Channel over the lower 20, 14, 13.7, and 13.1 miles of the St Johns River, widening along the Trout River Cut Range, Short Cut Turn and Training Wall Reach areas, and additional turning basins. In order to support project design and evaluate project impacts, a comprehensive approach including data mining to identify and gather available observed data, field data collection and a suite of hydrodynamic and transport models was implemented. This Attachment describes the approach for modeling, data mining and data obtained during the 2009 field data collection. Field data used in this feasibility study include data previously collected by the SJRWMD, USGS, NOAA, and NOS and the USACE 2009 field measurement study conducted for this project. The USACE 2009 field measurements were obtained using underway shipboard and mounted instrument platforms that collected data associated with tidal flows, discharge from the St. Johns River, Intracoastal Waterway and major tributaries, water surface elevations, along-channel and cross-channel gradients in velocity, salinity, depth, temperature and suspended sediment concentration. This data not only provides a better understanding of the processes and their interactions that govern the characteristics of the St Johns River but are also used for model input, calibration and validation for a comprehensive hydrodynamic modeling task. The hydrodynamic modeling task included the Adaptive Hydraulics Model (AdH), a two-dimensional hydrodynamic, sediment transport, and ship wake model of the Federal Channel and St. Johns River Estuary system and the ADvanced CIRCulation Model (ADCIRC), a coastal circulation and storm surge model, and development of the SJRWMD Water Supply Impact Study (WSIS) Environmental Fluid Dynamics Computer Code (EFDC), the MIKE21 FM Salt Marsh and Tributary hydrodynamic models and EFDC/CE-QUAL-ICM TMDL models for the Jacksonville Harbor GRR2 to assess the effect of the Harbor deepening project on salinity, water age and water quality. Coastal processes were investigated using the Coastal Modeling System (CMS) in the vicinity of the St Johns River entrance to evaluate shoaling due to littoral transport and to assess the potential impacts on the adjacent beaches due to channel deepening. The field data analysis and modeling results were used to design a deepened Federal Channel that will accommodate future vessel classes while minimizing impacts to the environment. Background The St Johns River flows south to north and is about 300 miles long. The total elevation drop from the headwaters to the Atlantic Ocean is less than 30 ft, with an average slope of about one inch per mile (NOS,1998). Most of the river is relatively shallow but the last 26 miles has an average depth of about 30 ft (Morris, 1995) due to the Jacksonville Harbor Navigation Channel. The main navigation channel is about 23 miles long and extends from the river mouth to near downtown Jacksonville (Figure 1.). Existing project depths in the navigation channel include 34 ft between the Talleyrand Terminal and downtown, 40 ft from River Mile 0 to 20, and 42 ft seaward of River Mile 0. 2 The total drainage area of the St Johns River is about 9,340 square miles and the average discharge is about 6,500 cfs at the river mouth (Morris, 1995). The total discharge is normally greater than 50,000 cfs and can exceed about 200,000 cfs (NOS, 1998, Sucsy and Morris, 2002). Smaller rivers, creeks and tributaries feed into the St Johns River, increasing the river flow, and affecting the tidal signal. Tidal influences affect the river more than 100 miles upriver. The total flow in the river is about 80 to 90 % tide induced. The remaining 10 to 20% is attributed to wind, freshwater inflow from tributaries and rainfall, point sources such as treatment plants. River flow is seasonal, following the seasonal rainfall patterns, with higher flows occurring in the late summer to early fall and lower flows occurring in the winter. The average annual nontidal discharge at the river mouth is about 15,000 cfs (NOAA, 1995). Wind and pressure associated with frontal passages and northeasters can cause subtidal water level fluctuations which are significant compared to the normally tide dominated flow. The more significant of these meteorological events cause flow reversals in tide dominated segments of the river. Figure 1. Existing Jacksonville Harbor Project Features. Methodology The suite of modeling tools are organized to support the iterative decision making process comprised of developing an initial alternative project design, benefits, then evaluating alternative project impacts 3 and costs, to ultimately arrive at an economically justified selected plan project design. The project design and impact considerations include the navigation channel features, such as deepening, widening, and turning basin that contribute to efficient and safe vessel operation (Table 1) and channel shoaling, coastal processes, waterlevels, salinity, and water quality. Table 1. Project Considerations PROJECT DESIGN PROJECT IMPACTS Deepening Riverine Channel Shoaling rates Turning Basins Littoral Processes in the Coastal Ocean & Shoaling Rates Wideners Water Levels –tide, storm surge, sea level change Vessel Handling Flows in Adjacent Embayments Bank Erosion Salinity for Environmental Impacts Water Quality for Environmental Impacts The criteria for selecting appropriate hydrodynamic models are also based on the objectives of the navigation study which are to optimize channel modifications and to assess project impacts. An important distinguishing characteristic of hydrodynamic models for the design purposes of this study is the model’s ability to efficiently represent channel modifications. The existing main channel is 400’ ft wide but can be as much as 1200’ wide in sections, and the alternatives under consideration do include widening the channel at Mile Point, Trout River, SW Blount Island, East Mill Cove and at the Terminal Channel. In order to accurately represent these modifications in a hydrodynamic model the horizontal grid resolution must be on the order of 50 to 100 ft. This resolution is not required in areas away from the channels. Therefore the most computationally efficient model would be based on a variable resolution grid. The AdH unstructured triangular adaptive mesh make this model a good choice for resolving the existing channel geometry and alternative channel widening features. In developing an integrated modeling approach, consideration has been given to existing and planned efforts by other organizations in order to gain mutual benefits where possible. As part of our model selection effort the USACE, Jacksonville District, has worked closely with the SJRWMD who originally developed the Lower St. Johns River hydrodynamic and water quality models for their WSIS and Total Maximum Daily Loads (TMDLs) (Sucsy and Morris, 2002). The USACE has made improvements to the EFDC model grids through the refinement of horizontal grid cells in the Federal Channel to improve representation of project channel alternatives. Adopting the SJRWMD WSIS models provides the opportunity to efficiently evaluate cumulative environmental impacts of the project, including USACE historic sea level rise (0.39 ft) and the SJRWMD WSIS future projection of 155 MGD upstream river water withdrawal, due to changes in salinity, water age, and water quality. The numerical models selected, to meet the objectives of the study are shown in Table 2. 4 Table 2. Model selection and primary tasks. / a - Model Level Surge Storm Water Coastal Coastal Salinity Riverine Shoaling Shoaling Currents Ship Sim Ship Boundary DO/ Chl Water Age Conditions Ship Wake Ship ADCIRC X X X ADH X X X X CMS X X EFDC X X X MIKE21 FM X X CE-QUAL-ICM X Observed Data –Describing Physical Characteristics – Informing Modeling and Analysis The modeling described in the previous sections is of limited value without adequate observed data to provide a better understanding of the processes and their interactions that govern the characteristics of the St Johns River Estuary and to serve as model input and as a basis for comparisons for calibration and validation of each model. The types of observed data that are required for the modeling described in the previous sections include bathymetry (Table 3), waterlevels (Figure 2), currents (Table 4), waves (Tables 5 and 6), wind, stream flow, rainfall, evaporation, salinity (Table 7), sediment characteristics, dissolved oxygen (DO) (Table 7), and chlloraphly-a (Chl-a). After identifying the types of observed data required, the next step is to gather data previously collected. Existing data were gathered from sources such as the SJRWMD, USGS, NOAA, and NOS. Once the existing data had been inventoried, any gaps in coverage were identified. Since the existing data has several sources and purposes no recent data including the basic physical parameters (concurrent currents, waterlevels, salinity, and waves) in the vicinity of navigation