Conservation Agency Battles Erosion, Preserves Wetlands with Computer-Aided Design Tools

Erosion Control

The Soil Conservation Service was born from a nightmare that
whirled out of the Plains states in the 1930s. Years of drought and poor
agricultural practices had stripped the earth of natural ground cover that held
the soil in place. When powerful wind systems swept across the parched land,
they churned up clouds of dust, darkening the sky and forcing the migration of
hundreds of thousands of people. This scene was described by John Steinbeck in
The Grapes of Wrath.

In the wake of the Dust Bowl, the U.S. Department of
Agriculture (USDA) began to see soil erosion as a national menace. The Interior
Department handles public lands, but because about 70 percent of land in the
United States is held by private landowners, the USDA created an agency
dedicated to controlling erosion by promoting responsible stewardship of
private land.

That agency's name has since changed to the Natural
Resources Conservation Service (NRCS), and it has become the Department of
Agriculture's lead conservation agency. In addition to monitoring soil quality
and working with landowners to ensure environmentally sensitive farming and
grazing practices, the NRCS restores wetlands to foster animal and plant life,
reinforces stream banks and designs terraces to control flooding. The agency
works to prevent runoff of sediments and animal wastes, and it builds dams to
control the growth of gullies that have cut into the slope of a hill over the
years.

Strong Local Presence

The NRCS was conceived as a vast network of local offices
that could be active on the most "micro" levels, engaged with
individual landowners and properties. Therefore, it maintains offices in 3,000
conservation districts, virtually one for every county in the nation. Along
with the NRCS, these USDA Service Centers usually include staff from other USDA
operations such as the Farm Service Agency as well as the local county
government's own conservation division. Since 1993, these centers have
experienced an average 78 percent increase in workload, while their staffs have
been reduced by 22 percent, according to the USDA.

To boost the productivity and efficiency of the NRCS staff,
a few years ago the Agriculture Department instituted the Service Center
Modernization Initiative that focused on bringing labor-saving technologies to
the field offices. These improvements include new computer servers, digital
cameras, Global Positioning System (GPS) devices for surveying and Geographic
Information System (GIS) software for the mapping and design tasks the field
staff routinely handles. Computer-aided design (CAD) products that use GIS and
GPS mapping advances are one of the tools that have allowed NRCS engineers to
make complex measurements more easily and generate designs for dams and wetland
restorations much faster than when their work was done on paper.

The NRCS operation in Wisconsin offers a model snapshot of
the agency's use of engineering software. Wisconsin has a higher percentage of
privately owned farmland than most other states, a robust network of local
conservation offices and some unique geographical challenges that make erosion
control a high priority.

Step One Is Topography

Wisconsin's NRCS headquarters in Madison is divided among
technical areas like geology, forestry, wildlife and grazing. The agency's
engineering division is overseen by John Ramsden. In 1998, Ramsden began
implementing electronic tools, including Autodesk products such as AutoCAD, the
basic drawing platform, and Land Desktop.

"Whether we're doing flood prevention, sediment
retention or building a terrace, the common task they share is that we need to
have topographical maps of the area we're going to design in," Ramsden
said. "So our technicians go to the project site and they take
measurements--it could be hundreds of points. These are downloaded into Land
Desktop, and at that point we can very quickly turn out a map showing surface
topography."

"This map becomes the base on which we layer design
features, and the software gives us the freedom to adjust volumes or
dimensions," Ramsden said. "We can very easily make a dam or an
embankment higher or steeper. We can see what an excavation would do to roads,
or make sure we're not infringing on a wetland. If the curves on a stream are
too sharp and we need to reinforce the banks, we can refer to the topography to
get the best stream alignment."

Many of the Wisconsin NRCS field offices are co-located with
the local counties' Land Conservation Department offices, and because the
majority of these were already using an Autodesk design standard, Ramsden said
this was another reason for NRCS to utilize the same platform. "We work
closely together with our local counterparts--we use the same federal manual
for design specifications," he said. "We need to be able to pass
files back and forth; it has to be seamless."

Pinpointing Site Locations

Mike Dreischmeier, an engineer in the NRCS Dodgeville
office, learned the software in 1995 as a county student intern. He remembers
what field engineering work was like before CAD. "You had to record
horizontal and vertical angles, stadia and rod readings, and then back in the
office you'd have to hand-plot them all on a drafting table," he said.
"Now you can just use a Total Station [for surveying] and plug it into a
computer. We can create 3-D digital terrain models to show surface contours.
When we move to design, we can plot cross-section and profile views of storage
pits, berms or drainage ditches we need to excavate."

Dreischmeier said one feature that has proved handy is the
ability to move in reverse--taking specific points from the map of an emerging
design and locating them out in the real world. "It allows you to locate
points that aren't tied to objects--for example, you're building an embankment
but you can't pull a tape measure out to the end of it from the corner of a
building. So, you put the instrument at the proper angle and then it directs
you out to the right spot accurate to a tenth of a foot. ''

Some Wisconsin NRCS offices use these products to layer
their maps and drawings over aerial photographs. If they are working on a
wetland, a small dam or a stream bank, engineers often use Raster Design to
"rubbersheet" the emerging design over an aerial photo, making a rich
presentation package.

Pilot Dam Rehab Project

The Eau Claire Area Office of the NRCS is in the
northwestern quarter of Wisconsin, in a region that was named the
"Driftless Area" because it was missed by glaciers. Whereas glaciated
terrain is much flatter and speckled with lakes, the topography of the
Driftless Area is steep and hilly, a high-relief landscape of grand bluffs,
crags and ridges perched over narrow, twisting valleys. Those factors mean more
erosion as stormwater flows faster down the hills, carrying sediments with it
and carving trenches into the land.

CAD tools have become essential for Laurel Qualley, a civil
engineering technician in the Eau Claire office who works primarily on larger
"pilot dams" that were built 25?30 years ago under a federally
funded project called PL 566. These dams that were built to block gully erosion
by channeling stormwater through pipes dug under earthen berms now are
beginning to fail. Their pipe seams are separating and allowing sediment to
seep in. U.S. Senator Herb Kohl won federal funds for NRCS to rehabilitate the
dams, and the first part of each job entails creating all-new AutoCAD drawings
to replace a pilot dam's original Mylar plans.

"We re-survey everything--the surface contours, the
dam's pool area, and we calculate how much grading we have to do, how much
water will be going through the pipe," Qualley said.

Restoring Wetlands

Beth Kleisath, an engineer in the Eau Claire office, works on
the agency's Wetland Reserve Program in which landowners receive a payment for
granting an easement on their land that allows NRCS to convert large plots back
into wetlands. If a farmer has dug ditches and installed tiles to drain water
from cropland, field staff will break up the tiles and plug the ditches so that
the field returns to its native wetland state again.

NRCS will excavate "scrapes" that will become
small ponds and attract waterfowl. The scrapes need to be built with varying
depths, with deeper scrapes holding water longer in a dry spell. "We try
to give the terrain a micro-topography, so it's not all one level," said
Kleisath. "Some plants and animals like six inches of water, others like
two feet."

If Kleisath is designing an earthen embankment in a wetland
or a gully, she uses a Land Desktop feature called Grading Wizard to figure out
volumes. "On the terrain map, I'll draw the length and height of the
embankment, and it will show the total volume of fill that is necessary for
construction," Kleisath said. "If we're excavating a manure pit, the
software calculates how much earth we'll have to remove."

"It's important because we can give these numbers to
contractors and receive accurate cost estimates for the projects,"
Kleisath said. "It's been a huge time saver for us."

Chad Mills is vice president of Autodesk Government at DLT Solutions in Herndon, Va. He has designed and implemented GIS solutions for government agencies since 1998.

Leave A Comment

  • Web page addresses and e-mail addresses turn into links automatically.
  • Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.

More information about formatting options

By submitting this form, you accept the Mollom privacy policy.