LETTER TO THE EDITOR
across their traditional areas of expertise. The ultimate goal
is to build a framework integrating geologic, hydrologic, chemical, and biologic properties and processes to allow scientists
to quantitatively describe specific vadose zone environments.
Their research will naturally fall into the following areas ofunderstanding basic processes and obtaining basic data as
identified in the Roadmap: Physical Description of Flow andTransport Processes, Chemical Transformations, Microbiology, Colloidal Formation and Transport, Multiphase Flow andTransport, and Unstable Processes.
It will be a long, gradual process before researchers cansimulate and visualize the vadose zone of a contaminated site
as an integrated system. Computations will be needed to interpret and reconcile data that was collected at different instrument support scales, collected over varying time periods, andcollected at different spatial scales. For this task, a new anddifferent set of tools will be needed which will help scientists
transcend their customary disciplinary boundaries in gaininga systems perspective by combining the basics such as: Understanding Coupled Systems, Scaling Issues, Estimating and Reducing Uncertainty, Improving Site Monitoring Systems, andIntegrating and Validating Site-Wide Models.
When funded, results of the research activities outlined above
will be improvements in our understanding and our capability
to monitor and model the fate and transport of subsurface
contaminants. To pursue these activities effectively and achieve
the anticipated results within reasonable time horizons, researchers need capabilities and facilities that do not yet exist.
Some of these are unlikely to become available without concerted attention and directed resources. Others will become
available much sooner, and provide a more powerful boost
toward achieving major results, if they are developed systematically rather than emerging haphazardly. Key elements of infrastructure and supporting capability as discussed in theRoadmap include: A National Virtual Library, Sensor Instrumentation, Sensor Networks, Testing Facilities, The ProblemSolving Environment, Advanced Numerical Algorithms, andHighpower Computing Capability.
The technical content of the Roadmap is captured in 61
activities, most of which have associated tasks and status points
within a time horizon of approximately 25 years. The detailsof the Roadmap activities provide the basis for selecting alternative research and development initiatives at any of the DOE
sites—providing the basis for the development of a programplan for implementation.
Many of the near-term results expected for both the research and infrastructure activities share a common theme:
moving the state of the art to the state of practice. This means
getting the current knowledge and capabilities already existingin the vadose zone research communities into operational use
at the nation’s priority sites of vadose zone contamination.
One benefit is that these tasks “pick the low-hanging fruit”,
providing quick returns because much of the research investment has already been made. A less obvious benefit is thatconcerted effort to get new knowledge and technical capability
into practice will bring researchers and solution-oriented problem owners into continuing and close interaction.
For the mid term, the Roadmap outcomes of greatest significance are likely to be the cumulative advances in monitoring

Letter to the Editor on A National Strategy for
Vadose Zone Science and Technology
We would like to make your readers aware of the recently
completed Department of Energy’s (DOE’s) National Roadmap for Vadose Zone Science and Technology, DOE/ID10871.
This Roadmap was published in August 2001 at http://www.
inel.gov/vadosezone (U.S. Department of Energy, 2001). Together with DOE’s Subsurface Contaminant Focus Area Vadose Zone Science and Technology Solutions (Looney andFalta, 2000), the Roadmap represents an important step indeveloping a national science program necessary to implement,fund, and coordinate interdisciplinary research into vadosezone fluid flow and contaminant transport and fate.
A team of scientists from a spectrum of federal agencies,
national laboratories, universities, and the private sector identified key areas of research necessary to improve our ability
to predict and monitor vadose zone flow and transport. Thesecategories include proposed research to: reveal the fundamental
nature of complex processes and their interactions at various
scales, develop sensors for characterization and monitoring, andenhance our computational capabilities to predict behavior
and performance. Significant emphasis was placed on delineating laboratory and field research programs dealing with bothporous and fractured media. Moving existing research andrecent technology developments into common practice wasidentified as an important priority for early implementation.
The Roadmap outlines a long-term program that also has
short-term potential benefits that cut across multiple federal
and state agencies subsurface needs. Within DOE, the vadosezone research effort has the potential to benefit some of theongoing environmental restoration projects as well as stewardship efforts. The broad scope of the research needs identified isapplicable to many other programs, including the U.S. Environmental Protection Agency, Department of Defense, U.S. Department of Agriculture, and U.S. Geological Survey, amongothers.
In 1998, the National Academy of Science was asked byDOE to identify the most critical contamination problems
within their complex of legacy sites, and to recommend along-term basic research program to address the subsurfacechallenges. The report issued from the National ResearchCouncil (National Research Council, 2000) identified significant knowledge gaps that are impeding the Department’s ability to clean up, stabilize, or contain subsurface contamination.
The Roadmap is a significant step in developing a response
to closing those gaps in the vadose zone.
The natural processes that occur in the vadose zone do notrespect the traditional disciplinary divisions between geology,hydrology, soil science, chemistry, and biology. Realisticallythere must be a multidisciplinary character to what is being
discovered, described, monitored and modeled in the vadosezone. To provide a complete picture of this interconnected
system, researchers will need to interweave theory (understanding), characterization and measurement (factual description), and prediction and integration (numerical modeling)

Published in Vadose Zone Journal 1:197–198 (2002).

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systems for contaminated vadose zone sites. A sound andefficient monitoring program is critical at major sites during
environmental cleanup and afterward, throughout any periodof stewardship required by residual contamination on-site.
The state of practice has been to monitor the groundwater atand around the site, rather than monitoring the vadose zone.
However, for many sites where contaminants are at somedistance from the water table, waiting until contaminants appear in the groundwater is less desirable than monitoring thevadose zone. If remediation can remove or isolate source
terms and halt plumes while they are still in the vadose zone,
groundwater contamination can be prevented. In addition, theeffectiveness of the remediation is often greatly enhanced,
and the cost significantly reduced, compared with groundwater
remediation alternatives.
Many of the long-term results anticipated from the roadmap
activities will provide better tools for supporting site-wide assessments and decisions on environmental cleanup and stewardship. Models and data gathering will undoubtedly improve
incrementally in the near and mid term. However, after a decadeor so of pursuing the Roadmap’s activities, a quantitative leap
forward (step change) is expected in the ability to visualize,
quickly and accurately, the current and projected future statesof site-wide vadose zone systems. These projections, which will
carry levels of certainty and sensitivity unattainable at present,
should help build the confidence of regulators and the public.
We invite the vadose zone research community to read,understand, and support the implementation of the National
Roadmap for Vadose Zone Science and Technology as a national research priority under a well-funded multi-agency research and development program.
Received 8 Nov. 2001
The National Vadose Zone S&T Roadmap Executive
Committee
Daniel B. Stephens, Daniel B. Stephens & Associates, Chair
Stephen J. Kowall, Idaho National Engineering and Environmental Laboratory, Vice ChairDavid Borns, Sandia National Laboratory
Darwin Ellis, Schlumberger
Lorne G. Everett, Stone and Webster, ConsultantsMartinus Th. van Genuchten, USDA-ARS
Michael Graham, Bechtel BBWI, Idaho
Frank Parker, Vanderbilt University
Edwin Weeks, U.S. Geological Survey
John Wilson, New Mexico Institute of Mining and Technology

References
Looney, B.B., and R.W. Falta. 2000. Vadose zone science and technology solutions. Volumes I and II. Battelle Press, Columbus, OH.
National Research Council. 2000. Research needs in subsurface science. National Academy Press, Washington, DC.
U.S. Department of Energy. 2001. A national roadmap for vadosezone science & technology understanding, monitoring, and predicting contaminant fate and transport in the unsaturated zone.
Revision 0.0. DOE/ID-10871. Available on-line at http://www.inel.
gov/vadosezone (verified 12 June 2002).