Flood thy neighbor: Who stays dry and who decides?
When rivers flood now in the United States, the first towns to get hit are the unprotected ones right by the river. The last to go, if they flood at all, are the privileged few behind strong levees. While levees mostly are associated with large, low-lying cities such as New Orleans, a majority of the nation’s Corps-managed levees protect much smaller communities, rural farm towns and suburbs such as Valley Park. Missouri. Valley Park’s levee saga captures what’s wrong with America’s approach to controlling rivers.
but “nobody wants to put up the money to watch and see what happens” afterward. “It’s really about what we want to spend money on as a nation.”
Researchers say this is a common problem in science and engineering. Whether it’s verifying levee models or doing long-term monitoring in ecological restoration, funding for initial projects dwarfs what’s available for follow-up research.
The federal government has the tools to get a much better picture of how levees worsen flooding, for a fraction of the cost of a comprehensive model. The U.S. Geological Survey, a scientific agency that monitors natural hazards, operates stream gauges that measure the flow of water in rivers.
In 2011, two scientists used stream gauges next to or directly upstream of levees to examine water heights during floods, as well as flow rates — the amount of water rushing past the gauge each second. The higher the flow rate, the larger the flood.
The scientists studied 13 levees in the Midwest, compiling these two measurements before and after the levees were built. They wanted to see whether floods with similar flow rates produced different flood heights before and after levee construction.
They found that in all 13 cases, for floods of the same flow rate, water heights post-levee were higher than pre-levee — in one instance by more than 5 feet. Co-author Nicholas Pinter, an earth science professor at the University of California, Davis, said the study used real-world data to show what actually happened during floods, instead of relying on a model of what “should” happen.
Scientists say stream gauges near every levee could serve as a warning system, indicating which levees worsen flooding and delivering a reality check on the Corps’ design predictions.
But the Geological Survey and other agencies have struggled to maintain their network of gauges. Due to tight budgets, the Geological Survey said only 73 percent of the gauges it considers essential for monitoring rivers are operational today. And because they are designed to track flooding, not the effects of levees, many gauges are far from levees, and some don’t track flow rates at
