ForumWEPP: Erosion Prediction for the Next Millennium
Farming near Klingerstown, Pennsylvania.
Imagine a day when farmers and ranchers can sit at their desks, click an
icon on their computers, and estimate wind and water erosion that could be
expected from each of the ways that they might manage their land.
Imagine, too, that they could just as easily estimate the effect of their
land-use decision on the movement of topsoil, water, and chemicals from their
farms and ranches into the air or as surface runoff, tile drainage, or
Producer decisions based on computer-generated if-then estimates could both
optimize real income and preserve, indefinitely, the natural resources that
production capability and profitability depend on.
Such decisionmaking is not as farfetched as it may seem. Agricultural
producers could make many of these predictions using ARS natural resource
models that have already been developed. And one important part of such a
scenario would be use of WEPPshort for Water Erosion Prediction Project
The WEPP project was conceived to replace the Universal Soil Loss Equation,
a technology initiated for use in conservation planning during Franklin D.
Roosevelt's second term. The equation has been used on nearly every piece of
agricultural land in the United States and in much of the rest of the world, as
well. To replace such a venerable technology has been a formidable undertaking.
WEPP has required more than a decade of extensive researchfrom
experiments on soil erodibility to statistical analyses for equations to
predict peak rate of runoff. In WEPP, we have married the science of soil
erosion to the immense power of the computer.
But to paraphrase Daniel Hillel, one of the world's foremost soil
physicists, what has been done in WEPP is no different than what scientists
have been doing for centuries. Essentially, WEPP developers have tried to
understand how nature operates in order to predict the future course of natural
events. These natural events are erosion events. And we predict them using a
WEPP will be an important tool to help managers select the best way to
produce on, and yet protect, a specific farm or ranchbased on its soil,
topography, and climate. It will help farmers keep their ponds clear and their
ditches free of sediment. It will help them meet any federal and state
requirements regarding erosion or sediment yield.
Under spray from the rotating boom rainfall simulator he operates, hydraulic
engineer Gary Frasier gathers information on soil infiltration and water
And WEPP will put a scientific base under the environmental standards and
expectations set by regulatory agencies. Not only will this help ensure
development of realistic standards for producers to meet, it will make possible
more accurate and irrefutable environmental determinations.
Naturally, the system of climate, soil, topography, plants, and management
practices that WEPP models is very complex. And not only must this system be
modeled accurately, but so must its individual components. This complexity is
why some foresee WEPP being used primarily by natural resource managers and
production consultantsrather than farmers and ranchersin the
However, continuing software developments should one day make it easier for
farmers and ranchers to apply the model themselves. Because ultimately, though
WEPP is a complex model, it is intended as an easy-to-use tool for a wide
variety of 21st century users.
Ideally, I'd like even schoolkids to one day be able to use WEPP in projects
related to urban construction and offsite sediment deliveryor in 4-H
projects related to agriculture and the environment. After all, my 10-year-old
grandson can already balance the managerial choices in SimCity, the computer
game, quite comfortably.
A continuing challenge will be to make WEPP the user-friendly tool that it
needs to be for maximum utility. This requires cutting-edge systems and
human-factor engineering, along with computer science. We're not there
yetbut we're getting there.
As it is, WEPP fits perfectly into ARS' mission: both improving management
and conservation of precious natural resources and supporting programs of other
federal agencies. WEPP integrates scientific knowledge into a tool that should,
in combination with others, help optimize the twin goals of resource management
and technology transfer.
Thanks to this and other ARS natural resource models, our agency is
providing the technology to sustainably manage the world's land and water
resources. Protecting the land becomes increasingly important as we face the
prospect of having to feed a growing population on shrinking acreage.
And implementing the new erosion prediction technology in the WEPP model
comes at a time when other problems are being approached similarly. For
example, a companion modeling project is related to wind erosion. Water quality
models have already been developed and are being applied.
Emphasis now is on bringing these models together so that they can use
common databases and run under a common user-friendly interface. The prospects
John M. Laflen
WEPP Project Leader