Nov/Dec 2013Earth and Water, Wind and Sun
Water, Water Everywhere - Or Is It?by David Lucas
Access to clean water affects every South Carolinian - from what comes out of our kitchen faucets to our collective ability to support agriculture and industry. The LW&C Division's Hydrology Section is responsible for providing the information necessary to effectively manage our water resources. Ultimately, such decisions must maintain a balance between the demands of human population growth and the preservation of habitats necessary for fish and other wildlife to survive.
"One thing we learned from the extended drought that occurred between 1998 and 2002 is that we do not have an unlimited supply of useable water," says Chief Hydrologist Joe Gellici. "Water is a finite and irreplaceable resource. Because it is essential to the health and welfare of all South Carolinians, to the economy, and to the environment, we need to determine how much we have, how much we''ll need in the future, and begin developing plans to meet our future demands. Believe it or not, it's possible that we could actually run out of useable water. It almost happened in 2002!"
The Hydrology Section will soon embark on a major study to assess surface-water availability in each of the state's eight major river basins using computer-based mathematical models (see "Water Planning - Predicting Supply and Demand" sidebar at left/right). On any given day, only about 1 percent of our useable water is on the surface in streams and lakes. Most is found beneath the ground, and most of that occurs in the coastal plain, where millions of gallons move through thick layers of subsurface sand and porous limestone called aquifers. In the piedmont and mountain regions, these layers of sand and limestone are absent, and a much smaller amount of groundwater is stored in fractures in the bedrock.
Mapping, studying and monitoring the coastal plain aquifers is a major part of the section's responsibilities. In 2009, DNR hydrologists and their counterparts in the U.S. Geological Survey began collaborating on a study to delineate and map all of the major aquifers and assess groundwater availability across the coastal plain. From this work, an initial groundwater flow model that will help guide future planning efforts was developed.
At the Creston site, Gellici watches with anticipation as the drilling crew brings up a core sample from nearly seven hundred feet beneath the surface - well into the Middendorf aquifer. The sandy, coarse-grained layer that the cores are showing is very promising in terms of the groundwater availability beneath the surrounding farmlands. Once the core samples have been recovered, the hole will be maintained as a monitoring well, providing ongoing information about the groundwater levels here for decades.
"Eventually, this will become a well-cluster site, with multiple wells, each monitoring the water level in a different aquifer, giving us long-term information about what the sustainable yields are - for instance how much can these farmers pump out of the aquifers over a ten- or twenty-year period say, without drawing down the water past a certain point," says Gellici. "It's a big investment up front, but you have to look at it in terms of the value of the information that you're going to get over the next fifty years. There's actually three different things this drilling project will support: there's hydrology, geology and also a USGS paleo-climatology study."
The Hydrology Section maintains a network of 115 groundwater monitoring wells like the one at Creston, and also collects data from thousands of water-supply wells. The data gathered from these efforts is available to the public. The Hydrology Section is also responsible for ensuring that fish and wildlife habitats and recreational uses are protected whenever hydropower plants and other facilities regulated by the Federal Energy Regulatory Commission are relicensed. Other projects undertaken by the section in recent years include a study aimed at restoring the wetlands habitat in a rare Carolina bay and a statewide inventory of springs - locations where groundwater flows naturally to the surface from rock or soil.
Water Planning – Predicting Supply and Demand
As South Carolina's population grows, so does the demand for clean water, and the DNR's Hydrology Section is spearheading efforts to address this critical issue. The State Water Plan (www.dnr.sc.gov/water/waterplan/index.html) calls for the development of a water-resources management plan for each of the eight major river basins in the state. Effective planning for water use is a complex scientific endeavor, but the elements that make up a successful planning strategy are fairly straightforward:
- Assess water quantity - How much water is available right now?
- Develop water-demand forecasts - How much will we need in the future?
- Predict potential water-supply problems using computer models - Where and when will shortages occur?
This critical area of research and planning is a work in progress that never really stops. Surface water supplies are monitored via gauges in rivers, streams and lakes maintained by the USGS, and groundwater supplies via a network of monitoring wells maintained by the DNR, SCDHEC, the U.S. Geological Survey and other partners. The development of sophisticated computer models capable of using the information accumulated from ongoing monitoring, historic data and trends in climate and population growth will help predict future usage needs and guide updates to the State Water Plan in the years to come.