CONTINUOUS HYDRODYNAMIC AND WATER QUALITY MONITORING IN SUPPORT OF THREE-DIMENSIONAL MODELING OF THE LOWER SAVANNAH RIVER ESTUARY

Applied Technology and Management (ATM) performed an extensive field data collection effort in the Lower Savannah River Estuary from August 1 through October 15, 1999. The 1999 Savannah River Data Collection Effort (99SRDCE) was performed to support the development of a three-dimensional hydrodynamic and water quality model of the Lower Savannah River Estuary. The model is being developed to support decision making in a Tier II Environmental Impact Statement (EIS) for the Savannah Harbor Expansion Project (SHEP) by the Georgia Ports Authority (GPA) and US Army Corps of Engineers (USACE).Data passing QA/QC protocols will be used to calibrate the three-dimensional hydrodynamic and water quality model. Capturing the amount of data necessary to represent the complex and, dynamic conditions of the Lower Savannah River Estuary offered many unique challenges and coordination of multiple resources, including review and approval from stakeholders, manpower, equipment, analytical laboratories, tidal and seasonal conditions and weather.The Modeling Technical Review Group (MTRG), a subcommittee of the Stakeholder Evaluation Group (SEG), worked with ATM to develop the scope of the 99SRDCE. The SEG has recommended various studies to address potential impacts of the SHEP identified in the Tier I EIS. The MTRG is comprised of leading modeling experts from the Corps of Engineers, Environmental Protection Agency, Georgia Environmental Protection Division, South Carolina Department of Health and Environmental Control, United States Geological Survey, City of Savannah, United States Fish and Wildlife Service, Savannah Chamber of Commerce, Skidaway Institute of Oceanography and other stakeholder representatives. Task Statements outlining the 1999 data collection effort were recommended by the MTRG to the GPA for implementation.The 99SRDCE was also designed to support the calibration of a three-dimensional water quality model capturing the system dynamics and sources affecting dissolved oxygen levels in the Harbor. The water quality model will be used to evaluate the effects of various Harbor modifications, ecosystem restoration alternatives and TMDL development. The 99SRDCE is one of the most comprehensive data collection efforts ever undertaken for the development of a Total Maximum Daily Load (TMDL) for the Lower Savannah River, providing an excellent example of how to develop, coordinate, and undertake proper and thorough data collection in support of modeling efforts.The following briefly describes the 1999 Data Collection Effort recommended by the MTRG and implemented by the GPA:Twenty-four Continuous Monitoring Stations were established throughout the Lower Savannah River Estuary. Both hydrodynamic and water quality monitoring instrumentation were deployed at the Monitoring Stations. Located at geographically significant locations in the estuary system from the entrance to Savannah Harbor (River Mile 0) to non-tidally influenced freshwater flow (River Mile 43), the instrumentation was deployed to capture the complex hydrodynamic and water quality conditions. Eight of the Continuous Monitoring Stations in Savannah Harbor had both bottom and surface instrumentation to capture the vertical stratification characteristics.Water Chemistry Samples were collected each week at each Monitoring Station for both high and low slack tide conditions. Laboratory parameters for the Water Chemistry Sampling Effort included BOD-5, CBOD-5, TKN, NO2/NO3, TSS, chlorophyll A, chloride and bromide.Three meteorological stations were established in the upriver, Harbor and entrance reaches of the Savannah River. Parameters recorded include wind magnitude/direction, rainfall, ambient temperature and solar radiation.Several innovative practices for instrumentation servicing and deployment were developed for the Data Collection Effort. Instrumentation mounting, servicing schedules, labor and estuary characteristics are examples of the unique challenges this data collection effort presented.