Low-Flow Studies Help Planners Anticipate Drought Impacts

What happens when there is very little water at a certain spot in a creek, river, pond or reservoir? How low do water levels have to be to trigger these impacts? Are they more likely to happen at some times of the year than at others? NDMC researchers conducting “low-flow” studies are asking these questions  for 50 sites in the Alabama, Coosa, and Tallapoosa (ACT) and Appalachicola, Chattahoochie, and Flint (ACF) River Basins and for 164 sites in the Upper Colorado River Basin. At each site a gauge monitors water flow or level.

The Advanced Hydrologic Prediction Service (AHPS) of the National Weather Service (NWS) will use the findings for warnings that accompany low-flow forecasts. The AHPS already  predicts floods and helps people anticipate flow impacts. There is a growing awareness that “low flows can also have harmful effects,” said Dr. Donna Woudenberg, the NDMC researcher who is leading the efforts.

The current low-flow studies are connected with pilot projects for the National Integrated Drought Information System (NIDIS), which was established by law in 2006. One of the main goals of NIDIS is to create a better early warning system for drought, which can be fine-tuned based on a detailed understanding of impacts.

What does she anticipate finding? “Increased population is putting stress on the system” in both Colorado and in the Southeast, Woudenberg said.

The task is huge, partly because awareness of drought impacts is not widespread. The process combines education and inquiry, Woudenberg said. At presentations in April to water-oriented groups in Georgia and in Colorado, Woudenberg outlined drought impacts for the groups, highlighting a few of the major economic, environmental and social effects of drought.

The current studies also involve more observation points than previous studies: the Upper Mississippi River Basin in Minnesota (2004) had 21 forecast points;  the North Platte River (2005) had 17; the Upper Missouri River Basin (2006) had 45; the Upper Trinity River Basin in Texas (2007) had 29; and the Red River of the North (2007) had 35. For some of the sites associated with managed reservoirs or rivers, researchers have a good idea who to call for observations on impacts. In other cases, researchers work their way down from state or regional officials to local water suppliers or others who may have an idea about the effects of low flows in particular spots. 

“It takes a lot of talking and asking questions to find somebody who understands what’s going on at the local level,” Woudenberg said. “Different entities handle water management in different states, so I have to work to figure out where the buck stops – who’s large and in charge.”

The low-flow studies have provided Woudenberg with a new appreciation for how different water management issues are from place to place. “In agricultural areas, irrigation is major,” she said. “In urban areas, it’s highly managed, to the point where flows are consistently maintained through treated wastewater.”

If you have information to contribute about what happens when flows are reduced at one or more of the gauge sites, please contact Donna Woudenberg, 402-472-8287, dwoudenberg2@unl.edu. If you know someone who may have information to contribute, please forward this along to them.

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