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GRAIP_Lite

Status
Ongoing

GRAIP_Lite is a streamlined and efficient way to predict road sediment impacts across watersheds and larger areas when field data are limited.  If you need to model  site specific road impacts on smaller project areas where field data can be applied, then the GRAIP tool set may be more appropriate. 

GRAIP_Lite uses DEMs, already existing road GIS layers with surfacing type information, and a small field calibration dataset to determine 6th code subwatershed scale road sediment production and delivery. Road layers are broken into GRAIP-style segments. Production is calculated in the usual GRAIP way, and delivery is based on the flow distance from the road to the stream and the calibrated probability of delivery at that distance. GRAIP_Lite is good at narrowing a large potential project area to the smaller watersheds with the most sediment problems. 

Though GRAIP and GRAIP_Lite share some elements, the two models are not equivalent. GRAIP is used to inventory and analyze forest roads at a fine road-segment scale, and utilizes an intensive field inventory to accomplish this. GRAIP results are spatially explicit within a few meters and can be used to locate, prioritize, analyze, and monitor specific road treatments. Because GRAIP is so comprehensive, the time investment often prohibits its application it on a scale wider than a 5th code watershed at a time.

GRAIP_Lite uses the same principles as GRAIP to determine broad-scale road surface sediment risks over a much wider area very quickly, and is used as a tool to determine where the largest problems likely occur on a 6th code subwatershed scale. Further work such as a full GRAIP inventory can then be applied in order to find the specific locations within the subwatershed that have problems that should be addressed. There is a minimal field component (to gather a calibration dataset), but most of the modeling uses existing datasets and can be completed in the office.

We suggest that you start in your areas of critical concern. In Oregon, Washington, and Idaho we are focused on roads impacting aquatic habitat for endangered fish species. We have worked on watersheds that are on the 303(d) list due to elevated fine sediment input. Other regions have concerns about road related landslides and gullies, post-fire effects and restoration, or decommissioning un-needed roads. GRAIP_Lite can help determine which watersheds in a larger area are likely to be most impacted by road surface fine sediment.

GRAIP_Lite Download

Nation-wide Model Runs for Watershed Condition Classification Assessments

GeoDatabase Documents and Information

Other documents

Downloads

Road Density, Proximity and Erosion Data (both unit sets1) and Stability Index Information by Forest Service Region data available here.

National Geodatabases

Road Density, Proximity, and Erosion Data for the entire U.S.

  • National SI GeoDatabase (contact team to request files)
  • National USC GeoDatabase

Stability Index Information for the entire U.S.

  • National Slope Stability GeoDatabase

    GRAIP_Lite uses the Standard International Units (SI) unit system commonly used in scientific and academic work. Since most users of this data are more likely to be using the U.S. Customary units (USC), and the thresholds for condition classes also use those units, we have done the appropriate unit conversions to provide a dataset using the USC units.  It is important to note that, since we are using a unit baserate, that any sediment production and delivery values are index values and are not representative of actual sediment masses.  If a baserate is known, however, they can be multiplied by that baserate in order to estimate actual sediment masses, but this baserate data is not widespread.  Likewise, all slope stability values are index values and local knowledge is needed for interpretation.

Past Case Studies 

Table of past GRAIP_Lite projects

What does GRAIP_Lite do?

GRAIP_Lite uses DEMs, already existing road GIS layers with surfacing type information, and a small field calibration dataset to determine 6th code subwatershed scale road sediment production and delivery. Road layers are broken into GRAIP-style segments. Production is calculated in the usual GRAIP way, and delivery is based on the flow distance from the road to the stream and the calibrated probability of delivery at that distance. GRAIP_Lite is good at narrowing a large potential project area to the smaller watersheds with the most sediment problems.

How do I download GRAIP_Lite?

GRAIP_Lite is a GIS tool for predicting the sediment delivery from forest roads to streams using minimal field data.  The required inputs are a road line and a DEM.  The model is a component of ArcHydro and runs in ArcGIS 10.3 and higher.  

Key Personnel

GRAIP_Lite Technical Team

  • Person
    Tom A. Black

    Tom A. Black

    Hydrologist
    https://research.fs.usda.gov/about/people/tom.black
  • Person
    Charlie H. Luce, PhD

    Charlie H. Luce, PhD

    Research Hydrologist
    https://research.fs.usda.gov/about/people/charles.luce
  • Person
    USDA Forest Service Logo

    Nathan Nelson

    Hydrologist
    https://research.fs.usda.gov/about/people/nathan.nelson

Data and Tools

Documents

Projects

Publications

Understory Publications

Last updated April 16, 2025
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