Scientists look at how climate change affects a major S.C. river
Imagine turning on the faucet and pouring yourself a tall, cool glass of ... saltwater.
That's what happened in 2002 when drought conditions turned the Pee Dee River’s normal flow of freshwater into a trickle. The reduced river flow allowed Atlantic Ocean seawater to move upstream and into municipal intake pipes.
“There’s not much anyone can do about weather and climate change, but we can think in terms of adaptation.”
"There's not much anyone can do about weather and climate change, but we can think in terms of adaptation," said Dan Tufford, a biology associate professor at Carolina who is leading a team of researchers in a study of the Yadkin-Pee Dee River basin, which feeds into Winyah Bay on the South Carolina coast. "We want to give water planners the ability to make informed decisions based on scientific predictions."
Multiple factors at work
The research, funded by a two-year grant from the S.C. Sea Grant Consortium, is examining the multiple factors that affect the Pee Dee River’s flow, including seasonal rainfall, summer heat and evaporation, agricultural irrigation wells that reduce nearby stream flow, rising freshwater demand, and rising sea levels.
The study is a microcosm of what's happening at similar coastal watersheds around the country in an era of climate change.
"Even with normal precipitation patterns, there will be a net decrease in river flow at the coast. That's because water demand is rising—which removes freshwater from the river—and sea levels are rising, which pushes saltwater further upstream,” said Kirstin Dow, a geography associate professor and co-principal investigator on the study.
What is a coastal water manager to do?
"They need to make informed decisions, but climate modeling isn’t quite up to the task; neither is watershed modeling," Dow said.
Creating a model
For coastal towns that depend on adequate river flow for freshwater, moving intake pipes further upstream to avoid saltwater intrusion from the ocean is a possible but very costly solution. With a refined climate and watershed model, water managers could potentially leave water intakes in place and simply turn them off when conditions point to brackish or saltwater intrusion in the river.
"What we especially want from a climate model is a forecast of the persistence of dry periods, and the models are not quite able to provide that," said Greg Carbone, a geography associate professor and co-principal investigator. "There is uncertainty with each step, and the best we can do for now is to offer a range of plausible scenarios."
Carbone, Dow, and Tufford hope to make incremental improvements in water flow models for the Pee Dee River and pass along the information to municipal decision makers.
"This is one small piece of a larger issue," Tufford said. "There are implications for population growth in coastal areas and the growing demand for freshwater in areas that are hard pressed to supply it under certain conditions."