USDA Forest Service GRAIP - Geomorphic Road Analysis & Inventory Package


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Introduction to GRAIP
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Boise Aquatic Sciences Lab
322 East Front Street
Suite 401
Boise, ID  83702

(208) 373-4340
(208) 373-4391 (FAX)

United States Department of Agriculture Forest Service.

USDA Link Forest Service Link


Introduction to the GRAIP Tool

The Geomorphic Road Assessment and Inventory Package (GRAIP) is a process and a set of tools for analyzing the impacts of roads on forested watersheds. GRAIP combines a road inventory with a powerful GIS analysis tool set to predict sediment production and delivery, mass wasting risk from gullies and landslides, stream diversion potential, culvert maintenance, and fish passage at stream crossings.

The road inventory protocol describes how to systematically field inventory a road system using
GPS and automated data forms. Once downloaded, these data can be immediately run through a data quality checking and correction program. Quality checked data can then be analyzed in a program implemented in ARC-GIS. The program produces maps of surface erosion, accumulated road sediment in streams, and contributing length by segment, which relates directly to slope stability and gullying risks. Other analyses relating to stream diversion potential, stream crossing failure, culvert maintenance needs, and fish passage are also provided with the program.

Why use the GRAIP tool | Outline of GRAIP Process | How GRAIP Works

Why use GRAIP?

  • GRAIP predicts multiple environmental impacts of forest roads including:

    • Sediment production

    • Sediment delivery to channels

    • Hydrologic connectivity

    • Gully initiation risk

    • Landslide initiation risk

    • Stream crossing occlusion and failure risk


  • GRAIP documents road sediment delivery problems at specific locations. 

ArcMap Display

  • Understanding sediment production and delivery at a road segment scale helps optimize allocation of road maintenance and repair funds to address the largest sediment issues first.  In some watersheds (such as the one used to generate the plot below), much of the sediment is delivered from a small fraction of the road network.

Sediment Delivery & Drain Points

Click for larger image

  • GRAIP quantifies road surface erosion and predicts sediment delivery to channels, which aids in watershed sediment source assessment and TMDL development.  Sediment accumulation through the channel network can help visualize hotspots and aid prioritization of work.

Road Sediment Acumulation per unit area map

click for larger image

  • GRAIP can be used as a monitoring tool to quantify the geomorphic impacts of road engineering projects.  Data shown below illustrate sediment changes from before and after surveys of a road decommissioning project.


Drain Type

Δ Count

Δ Sediment

Production (kg)

Δ Sediment

Delivery (kg)

Δ Sediment Production (%)

Δ Sediment Delivery (%)

Broad Based Dip






Diffuse Drain






Ditch Relief Culvert






Lead Off Ditch












Stream Crossing


















All Drains












Outline of GRAIP Process

Print Process Outline

Overview of GRAIP Process



How GRAIP Works

Road Decommissioning: Picking the Right Road - Science Briefing (PDF)


How GRAIP Works (PDF Power Point presentation)


Road Inventory and Monitory with GRAIP - CDM Water Resources Discipline Webinar (.wmv file). Introduction to GRAIP Road Studies in the Western US - including some examples. August 17, 2010.


Running TauDEM (PDF)




USDA Forest Service - GRAIP - Geomorphic Road Analysis and Inventory Package
Last Modified:  Tuesday, 22 April 2014 at 14:05:51 CDT

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