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U.S. Dept. of Agriculture |
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USDA Forest Service |
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Forest Service Research |
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Rocky Mountain Research Station |
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other main links |
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Boise Aquatic Sciences Lab (208) 373-4340 |
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Frequently Asked Questions
Questions and Answers from Trainings
Do I have to know GIS to run GRAIP? GPS? Road Inventory? Can you use existing data in the GRAIP package? How? Is the process project based? (watershed/forest/etc). Can you use an ATV? Walk? Bicycle? What are some other tools I can use? What are some advantages of using this package? What is included in the model download? What time do I enter in the road line TIME1 field? When do you lump and when do you split things out in the field? Why should I run TauDEM before going into the field? What other prep-work should I do? How long will it take to complete my project? How long will the pre-processing take? How long will the computer processing take when I get back into the office? How detailed should the field comments be? Calculating the GRAIP Base Rate
Do I have to know GIS to run GRAIP? GPS? Road Inventory? 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. Can you use existing data in the GRAIP package? How? 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. Is the process project based? (watershed/forest/etc). 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. Can you use an ATV? Walk? Bicycle? 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. What are some other tools I can use? (SEDMODL2, WEPP, R1/R4, FishXing? Etc) 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. Fish 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. What are some advantages of using this package? GRAIP has 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. This sounds great, but we have limited funding. Where should I start? 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 proximally connected. Required Software
What is included in the model download? When you follow the link on the GRAIP downloads webpage to the GRAIP download site you will be directed to install TauDEM, SINMAP, Hawths Tools, GRAIP GIS extensions for the toolbar. These are all required to run the full version of the model. Which roads do I inventory first? 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 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. This occurs 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. What time do I enter in the road line TIME1 field? 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 When do you lump and when do you split things out in the field? 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 location. 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 road line. Why should I run TauDEM before going into the field? What other prep-work should I do? 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 DEM.
This could 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. The solution 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. If this does not resolve your issue please drop us a note. How long will it take to complete my project? 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 their work. How long will the pre-processing take? 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. How long will the computer processing take when I get back into the office? 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. How detailed should the field comments be? 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.
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USDA Forest Service - GRAIP - Geomorphic Road
Analysis and Inventory Package
Last Modified:
Tuesday, 28 February 2012 at 18:31:45 EST