New Stream Maps Could Aid in Sustainable Development

Researchers have developed a new method designed to determine where rivers begin.

Already, scientists using it have created maps of the Potomac River watershed system that reveal the impact of urbanization on aquatic ecosystems in greater detail than ever before.

Urbanization reduces soil absorption through the application of hard, impervious surfaces. As a result, runoff is created, pulling with it large amounts of sediments and pollution, which is then deposited in streams and bodies of water.

"For the first time, we have an accurate representation of where streams once flowed through major urban areas of Baltimore and Washington, D.C. and where streams currently flow through forests," said the study's lead author Andrew Elmore of the University of Maryland Center for Environmental Science's Appalachian Laboratory. "This information is critical for quantifying the impact of urbanization on aquatic ecosystems."

The new, high-resolution maps span from the Appalachian Mountains to the Chesapeake Bay, showing streams that flow through forests and fields and predicting the location of streams that have since been built over.

The results showed that the maps currently guiding land use decisions under-represent stream density in the Potomac River by as much as 250 percent.

"High-quality maps of natural resources, including streams, is a prerequisite to sustainable development," Elmore said. "However, such maps do not currently exist for large areas, severely limiting our ability to understand, protect, and restore the ecological functioning of these natural assets."

In order to some how take into account "missing streams," or those buried beneath development, the scientists collected data on stream occurrence in surrounding regions and then related it to several variables having to do with stream presence. Based on the outcome, the scientists were able to project where streams likely existed prior to human interference.

The results, according to the researchers, can be used to examine how much land use has influenced the number and length of streams.

"We intend our results to advance ongoing research by providing a useful high-resolution stream map for this region and a new methodology for future applications in other regions," said Elmore.