FACULTY PROFILE: Steven
Loheide
 utfit Steven
Loheide with a pair of wings, and he’d be happy. Give him
a small aircraft, and he’d be ecstatic. On the ground, Loheide
studies the many interconnected factors that affect stream and ecosystem
health. However, he does some of his best field work from the sky, where
his latest research tool—an unmanned aerial vehicle—provides
him a cost-effective way to collect high-resolution thermal infrared
images that paint a colorful landscape of temperature variations in
and around a stream.
Pinpointing water temperature and temperature variations
across such an ecosystem can tell researchers whether the water is too
warm for native species to survive. It can indicate whether the water
table—and thus, the supply of fresh, cool groundwater—is
low. In such areas of California, water-starved native meadow plants
die off and sagebrush and dry grasses take their place. These are consequences
of human-induced erosion; ultimately, the stream channel slices lower
and lower, routing rainwater downstream instead of spilling the excess
gently over the meadow.
Loheide earned his PhD in hydrogeology from Stanford
University and joined the department as an assistant professor in fall
2006. He hopes his remote-sensing techniques will enable him to monitor
large-area ecosystem restoration projects so that experts can track
their progress over time. “There’s roughly $1 billion a
year being spent in the United States on stream restoration projects
and of those restorations, only about 10 percent are monitored to determine
whether they’re successful or not,” he says.
His solution is to monitor those areas remotely,
taking some “point” measurements in the field and then using
his unmanned aerial vehicle, coupled with imaging technologies, to gather
much more data in a spatially distributed, time-saving way.
Located in the northern Sierra Nevada range in California,
the Feather River Watershed drains more than 3,200 square miles of land
into the Sacramento River and other major water bodies, including Lake
Oroville, the second-largest California reservoir. Some 140 years of
mining, grazing, timber-harvesting, wildfire, and railroad and road
construction are among factors that ultimately degraded more than 60
percent of this massive watershed. “Those land-use practices change
the stream morphology,” says Loheide, who conducted his doctoral
research in the watershed. “They cause increased runoff and incision
of the stream channels.”
For his research, Loheide monitored restoration efforts
that the Feather River Coordinated Resource Management group initiated
near the city of Quincy, California. For the group’s ongoing restoration,
crews are using an unproven technique called “pond and plug,”
in which they excavate large ponds and use the sediment to fill in portions
of the incised stream channels. “They completely destroy the incised
channel and reroute flow—in this case, to an abandoned stream
channel on the flood plain,” says Loheide. “That causes
a raise in the water table and a transition from the dryland grasses
back to the native sedges and rushes.”
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Loheide
shown standing in a patch of native sedges in an incised area
of the Pecatonica River in southwestern Wisconsin, while PhD student
Eric Booth is standing in grasses that have spread due to grazing
practices adjacent to the river’s east branch.
(View larger image)
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The method has moderated floods and flood pulses,
says Loheide. “What’s less clear is whether it releases
water slowly to the stream during the summers, which was one of the
goals,” he says.
During his research, Loheide developed a new technique
for mapping evapotranspiration, or the flux of water from the land surface
into the atmosphere. “Just like perspiration, when water is evaporating
off your skin, evapotranspiration causes a cooling effect,” he
says.
With his imaging equipment, he can detect areas of
low and high evapotranspiration and, via an algorithm he developed,
quantify how much water plants are transpiring. The information is important
for water budget studies and water resources questions. In California,
those questions are particularly relevant, since the Lake Oroville reservoir
provides water for two out of three state residents. “We know
how much precipitation we get, and now we know how much is going toward
runoff and how much is going toward evapotranspiration,” says
Loheide. “Knowing how much water we will have in our reservoirs
helps managers allocate water for municipal, agricultural, industrial
and river ecosystem uses.”
He also incorporates such data as seasonal stream
flow information, water table depths, and precipitation and snow-melt
estimates into 3-D models that can answer questions about what’s
going on underneath the ground. In this ecosystem, existing vegetation
depends on groundwater, so he can use the models to predict vegetation
patterns by allowing the model to iterate until it converges on a stable
pattern. “In a fair number of restoration projects, the vegetation
doesn’t respond as you’d expect—mostly because there
aren’t quantitative measures of predicting that,” he says.
“This is an area in which we are hoping to make a difference.”
In Wisconsin, Loheide will set his unmanned craft
in flight in the state’s Driftless Area—a region in which
more than a century of agriculture and erosion has deposited sediment
into stream channels. There, he will use thermal infrared imagery to
differentiate between springs, which are very concentrated groundwater
discharge points, and areas of more diffuse groundwater discharge. He
hopes to learn more about the nature of groundwater flow: whether it’s
trickling slowly through a large part of the geologic substrate and
sediments or whether it’s flowing mostly through fractures and
preferential channels.
His findings will shed light on the water quality
in those areas and, as in California, will help to answer questions
about the efficacy of restoration techniques. In addition, organizations
like Trout Unlimited may use Loheide’s findings as the basis for
improving the brook trout population throughout the upper Midwest.
As an undergraduate, Loheide began as a environmental
chemistry major whose interests gradually leaned toward geology and
ultimately morphed into hydrogeology. “I always have had strong
environmental beliefs and that led me into this environmental and restoration
work,” he says. “It’s also really important to me
to feel that people outside of the academic world are using and interested
in my work.”
In the future, he may study infiltration basins for
treating potentially contaminated stormwater runoff. “There may
be a way to use more vegetation within these to do a better job of capturing
sediment, increasing the infiltration in soil and increasing the vegetative
uptake dissolved contaminants like nitrogen,” says Loheide.
He also hopes to examine ways to predict how vegetation
and groundwater systems could evolve as a result of climate change.
Loheide enjoys hiking, backpacking and camping treks.
He and his wife, Beth, have a baby son, Quincy—fondly named after
Loheide’s field site in California.
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