Geologists putting region’s overlooked streams on the map
Maps will help municipalities when planning for projects and development.
When geologist Andrew Elmore came to the University of Maryland’s Appalachian Laboratory in 2008, he wanted to familiarize himself with the data on the area’s streams, the bedrock of his area of study.
It didn’t take long for Elmore to realize the data he sought didn’t exist.
The National Hydrography Dataset, which the U.S. Geological Survey has used for more nearly 100 years to map streams, was missing many of the waterways. Some of the unmapped streams had been buried long ago, trapped in culverts to facilitate development. Others were too small to be part of the map. Still others were so deep in forests that those charged with searching for the streams never found them.
As a result, counties and states were making important land-use decisions based on incomplete maps, which resulted in burying more unknown streams and harming others.
“Anytime you make a decision about how to regulate an industry, you need to know what kind of resources will be put in jeopardy by that activity,” Elmore said. “Streams are hotspots for biodiversity and nutrient cycling. To be able to know where they are is really a prerequisite for managing them properly.”
In the absence of maps, Elmore decided to make his own. It took four years, but Elmore and his fellow researchers now have maps of all of the watershed’s streams west of the Chesapeake Bay and a research paper explaining how they drew their conclusions.
To make the maps, the researchers walked streams with GPS devices in hand, from top to bottom. In streams where there was no water, researchers looked for eroded banks and beds. To account for missing streams, the team used a computer model that looked at real-time conditions overlaid with maps that showed how impervious surfaces — roads, parking lots and buildings — had grown. The result is a map where streams would be flowing if they had not been buried.
Elmore wasn’t starting from scratch. He and Sujay Kaushal, a colleague at the University of Maryland Center for Environmental Science, collaborated to map the buried streams in Baltimore and its suburbs in 2008 and 2009.
As a result of the recent mapping work, the University of Maryland researchers found two-and-a-half times more streams than were in the National Hydrography Dataset. That data is updated every year, Elmore said, but states have different levels of participation in the study, and the study doesn’t count the streams that were buried long ago. Elmore’s work does, which makes his maps representations of potential streams.
Elmore said he envisions the map as a desktop planning tool for counties and cities looking at projects. A classic example, he said, would be a logging operation. A company wants to cut down trees, so a land manager would want to make sure the trees are not cut down within a certain distance of a stream. The tool allows that land manager to figure out what that distance is. Already, Elmore said, county planners have called, seeking customized maps for their area. He and the other researchers have helped those officials access the data and interpret it.
The maps’ importance will increase as energy companies seek to develop Marcellus Shale drilling in Western Maryland. In Pennsylvania, where drilling has occurred for the last five years, drilling sites, access roads and pipelines have fragmented many forests. Spills of drilling fluid have polluted streams deep in the forests, resulting in fish kills. Initially, when drilling began, some streams went dry because drillers withdrew so much water.
Elmore expects the data could become a flashpoint with Marcellus drillers, who will want to use the less comprehensive national dataset instead of the University of Maryland maps. Already, a coal mine wanted to expand in an area and relied on the national data set. Maryland’s Department of Natural Resources came back with Elmore’s map. Eventually, the parties agreed to use the national dataset, but Elmore said just having the data was helpful in whatever negotiations took place.
But discrepancies between the two sets may not last much longer. The U.S. Geological Survey has requested Elmore’s data. And Elmore is hoping that, one day soon, a brigade of citizen scientists will help ground-truth the maps.
He hopes that hikers, bikers and other outdoor enthusiasts will be able to take a photo of a stream they see and send it in real time to Elmore’s network with the latitude and longitude embedded in it. If that stream is not on the map, it can be added right away. That will mean constant updating.
“That would be the coolest thing, to have it be an interactive system, so the map would be able to automatically update, so the maps would become validated in real time,” Elmore said. “The best way to move forward in this day and age, with the technology we have, is to elicit the help of all the citizens.”
To see the stream maps and map your own local watershed, visit http://streammapper.al.umces.edu.
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