It is not mandatory to have a high level of GIS or GPS training to begin working with GRAIP. It is important to have a basic familiarity with ArcGIS and to be willing to learn. If your GIS skills are minimal it will help to take a basic GIS review course online or to have assistance from a local GIS specialist to get you started. We are willing to help people with basic GIS skills to learn the process and we periodically offer training in the use of GRAIP. The GPS equipment and inventory procedure are fairly intuitive and most students are functional after two days of training.
GRAIP depends on having precise location
information about where water leaves the road and if that water is reaching the
channel network via a surface flow path. Few people collect the location data
of the drain points as part of routine road inventories so it has been hard to
utilize this data in GRAIP. It is theoretically possible to make this work, but
so far the right data has not been available to try it.
GRAIP has been used at a variety of scales
from small road realignment projects to 5th code HUCS. The scale that is chosen
depends on the goals being pursued. Many users have used GAIP as a way of
prioritizing where to focus restoration and road improvement work in basins with
known sediment and aquatic habitat issues. The GRAIP package will provide
predictions about the amount of road sediment that is entering the channels in
the area and from where that sediment originates. GRAIP also provides
predictions of gullying and landslide initiation below roads.
The road inventory data can be collected
from a variety of platforms as long as a GPS receiver and appropriate data
recorder of some sort are available. Past surveys have been conducted from
vehicles, but it is often necessary to cover closed roads and infrequently used
roads and trails by bicycle, ATV or on foot. The distance covered by a data
collection crew depends on the terrain, road type and GPS coverage. The typical
inventory data collection rate has been about 5 miles per day with a range of
one to ten miles.
There are a variety of tools that have been
developed to predict the impacts of roads on the environment.
WEPP is a physically based model that
predicts water and sediment movement on hillslopes and roads. There are a
variety of formulations and interfaces for the basic WEPP model that can
simplify its use for various purposes.
WEPP Road is a web based tool for estimating sediment production from a
road segment given the input parameters of road length, road slope, road width,
surfacing type, soil texture, road prism configuration and traffic loading.
Climate files are provided that are used to simulate and drive the runoff and
sediment predictions. Sediment delivery estimates can be predicted based on
user inputs about the conditions below the road drain point. The inputs are
soil texture, slope gradient, and flow path length. WEPP Roads is useful for
quickly estimating the magnitude of sediment production from average road
configurations and calculating the benefits of road improvements. It is not a
spatially explicit model for road sediment so it may not capture the watershed
scale effects of the road network.
The R1/R4 model (USFS 1981) including
Boised, NezSed and other related models have been used by the Forest Service in
the Rocky Mountain region to predict sediment production from roads, harvest
units and burned areas. The road component of the model uses disturbed area,
road slope, road age, erosion control mechanisms and road usage to calculate
sediment production. Sediment delivery is estimated by assigning a delivery
ratio to the land types on which the road is constructed.
SEDMODL2 is a model for predicting sediment production and delivery from
forest roads developed by Boise Cascade and NCASI. The model works in GIS
environment and like the R1/R4 methods it uses a linear combination of road
factors to predict sediment production. Sediment delivery is based on road and
stream proximity. Detailed information on drain point location is not
mandatory, but is supported in later versions of the model.
Xing is a tool kit for predicting fish passage through stream crossing
features. This is a powerful tool that depends on a detailed survey of stream
crossing and channels to predict the hydraulic conditions that will occur.
These predictions are compared to the capabilities of a host of aquatic species
to predict if and when the crossing may be a barrier to passage.
The fish passage criterion used in GRAIP are
based on a simplified set of assumptions from the literature and should be
considered a first approximation indicating if further scrutiny is warranted.
If FishXing surveys have been completed they can be used in place of the
calculations made by GRAIP.
several advantages over other approaches to predicting the impacts of roads on
natural resources. GRAIP excels at helping managers prioritize BMP and
restoration decisions. The GIS based output simplifies the assimilation of the
information by managers and facilitates the use of the information in
prioritization decisions. GRAIP is able to use locally developed erosion rates
to predict sediment production and delivery on a local and a watershed basis.
It is a GIS based tool that uses a field inventory to determine the flow paths
of water and where water and sediment actually leave the road. The road
inventory data that are collected are easily updatable and useful for
documenting changing watershed conditions. The model predicts the risk of gully
initiation below road features and predicts the risk of road drainage related
landslides. The model also predicts which stream crossing culverts may be
impassable to fish and be subject to blockage by debris jams. The output of
GRAIP can be easily displayed in the form of maps showing areas of high sediment
delivery to channels and the road segments and drainage features that lead to
the elevated risk.
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 or
decommissioning un-needed roads.
If you are going to try using GRAIP on a
project scale test to model the change in sediment delivery, choose a project
that has a sizeable road/stream interaction. A small timber sale on a ridge top
location with .6 miles of temporary road may not show a substantial sediment
impact in GRAIP if the roads do not approach the channel. GRAIP is good at
finding sediment sources to reduce as the road and channel network become more
It depends on the goals of the project. If
the goal is to asses the road geomorphic impacts on a 6th code HUC for a
management project it would be sensible to do all of the open and drivable roads
first and then move to the roads that do not have vehicle access. It is
recommended that the inventory progress in a systematic fashion through the road
system, to maximize efficiency and minimize gaps or duplication. The system
works most smoothly if the inventory is conducted from the stream bottoms
towards the ridges.
We have found that the GRAIP model is quite
sensitive to minor changes in the data dictionary. We do not recommend editing
the data dictionary without first discussing the implications with Tom or
Charlie. It is crucial that the data dictionary and the GRAIP model version be
synchronized. Feel free to email Tom Black at firstname.lastname@example.org to be sure
that you have the latest versions available.
All of the
drop down menus in GRAIP lost their functions and were labeled “Untitled” when I
tried to calculate the direct stream sediment input.
when the spatial analyst functions are called but the extension is not
activated. In ArcGIS go to Tools\Extensions and check the Spatial Analyst box.
If this option is not installed you will have to go to the Tools\Customize menu
and load the extension.
The TIME1 field in the road line should
match the auto assigned TIME field in the corresponding drain point. The value
needs to be rounded (not truncated) to whole minutes 30 seconds = round up. The
TIME1 and TIME2 field should be entered as 12 hour time HHMM
It is important to keep the big picture in
mind when deciding when to lump or split. The first rule is that we do not
split road segments finer than 20 meters in length. It is generally possible to
route the water and sediment to the correct location within this distance. If a
water leaves the road through two separate drain points located in close
proximity (say two non-engineered broken berm features) it is logical to treat
them as one feature. This is generally the case as long as the sediment routing
is not affected and that the main infrastructure of the road is still recorded.
It is not advised to skip any pipes for example even if they are in the same
If a road is flat and is drained
periodically by a series of diffuse drain points such as micro-rills, it is
reasonable to minimize the number of diffuse drain points. If these drain
points do reach a channel it is important to locate them and their contributing
road line carefully so that the drain point is located at the downslope end of
the road segment. A non-diffuse drain point should never be located in the
middle of a road segment, as the slope of the road may be incorrectly
calculated. Slope is calculated based on the beginning and end nodes of the
TauDEM is run before going to the field so
that the field crew knows where GRAIP thinks the channel network is located. If
there is a divergence between the modeled network and the observed network, then
the field notes will be critical to assign the stream crossing point to the
correct channel. If a systematic error is noticed between the TauDEM network
and the observed network, it is best to resolve this before further data
collection. Possible resolutions are changing the minimum contributing area or
if an offset is observed adjusting the spatial reference between the GPS and the
be due to a problem with spatial registration of the GIS layers. Double check
that the shape files with your drain point and road line data are in the same
projection. If you check the layer properties of the GRAIP drain point and Road
line files, under source the coordinate system should be the same as that of
your base DEM. If this is not the case (or the coordinate system says
unspecified) your drain points will never really match up with your DEMNET
streams and the resulting calculations will not work correctly. ArcGIS will try
to register the layers on the fly to display the data, but the underlying data
may still be miles apart.
is to open the DEM, find out its spatial reference (datum and projection), and
re-project your shape files into that spatial reference system using the tools
in ArcToolbox. The base DEM needs to be a grid.
Past field projects have progressed at an
average rate of 5 miles per day. Like the stock market, your results may vary
depending on a variety of factors including; the work schedule, commute
distance, local GPS reception, road construction and degree of topographic
dissection. We will have a better idea as more people share the results of
The pre-processing is relatively quick to
run. If the data dictionary is not modified it should only need user input to
correct roads that do not drain anywhere and to double check that drain points
that do not have any drainage assigned to them are correct.
The rule of thumb has been one day of
pre-processing, editing and running for every week of data collection. It is
important pre-process the data frequently enough to find any problems while the
crew is still working in the local area. There will be places that need to be
revisited to confirm drainage information or fill in data gaps.
The comment field in the drain point is
important to fill in when something unusual is occurring. The stream crossing
field will always need a comment indicating if the point is located on the
TauDEM channel network or not. In some cases stream crossing points will need
to be snapped to register with the TauDEM streams, and this requires some field
input to determine if a channel is a 2nd order or a 4th order channel.
If you enter the drain point identifier only
once, GRAIP will route half of the sediment to the drain and assume that the
other half is not delivering. If the full width of the road is delivering to
the drain then enter the drain identifier in both TIME 1 and TIME2. If the road
is truly crowned and only delivers from one side, then enter 999 in the TIME2
filed of the road line.
Other than the GRAIP User Community, there are also local commercial options to troubleshooting, technical support and equipment ordering.
The ones listed below are local to the Boise area. If users have other commercial options, they are free to contact us to request adding them to this list.