92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012
Development of Decision Support Systems for Estimating Salinity Intrusion Effects Due to Climate Change on the South Carolina and Georgia Coast
Hall E (New Orleans Convention Center )
Paul Conrads, USGS, Columbia, SC; and E. Roehl Jr., D. L. Tufford, G. Carbone, K. Dow, and J. C. Whitehead

The ability of water-resource managers to adapt to future climatic change is especially challenging in coastal regions of the world. There are many municipal water intakes along the Georgia and South Carolina coast that are proximal to the saltwater-freshwater interface of tidal rivers. An increase in the extent of saltwater intrusion along the coast due to climate changes could threaten freshwater intakes for several major cities along the coast. Water-resource managers need estimates of the change in the frequency, duration, and magnitude of salinity intrusion near their water intakes that may occur as a result of climate change. Salinity intrusion results from the interaction of three principal forces - streamflow, mean tidal water-levels, and tidal range. To analyze, model, and simulate hydrodynamic behaviors at critical coastal gage locations along the Atlantic Intracoastal Waterway and Waccamaw River near Myrtle Beach, SC, and Savannah River near Savannah, GA, data-mining techniques were applied to over twenty years of hourly streamflow, coastal water-quality, and water-level data. Artificial neural network (ANN) models were trained to learn the specific variable interactions that cause salinity intrusions. Streamflows into the estuarine systems are input to the models as time-delayed variables and accumulated tributary inflows. Tidal inputs to the models were obtained by decomposing tidal water-level data into a “periodic” signal of tidal range and a “chaotic” signal of mean water levels. The ANN models were able to convincingly reproduce historical salinity dynamic behaviors in both systems. User-defined hydrologic and coastal water-level inputs from down-scaling of regional climate models can be simulated in the salinity intrusion models to evaluate various climate-change scenarios. The models for the two systems are deployed in a decision support system and disseminated as a spreadsheet application to facilitate the use of the models for management decisions by a variety of coastal water-resource managers. Preliminary model results near a municipal freshwater intake indicate that a sea-level rise of 1 foot (30 centimeter) would double the daily frequency of brackish water over a seven year model simulation. Water-resource managers can use this information to plan mitigation efforts to adapt to potential effects from climate change.

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