US Forest Service, Tongass National Forest
Tongass National Forest, Riparian Management Areas (RMA), 2013
This feature class contains polygons which depict Riparian Management Areas on the Tongass National Forest. The script is in T:\FS\Reference\GeoTool\r10tnf\ToolboxDelineation of the Riparian Management Area (RMA).The GIS polygon layer that depicts the Tongass Land Management Plan (TLMP) Standard and Guideline Riparian Management Area is a critical analysis and planning tool for delineating the Riparian Management Area (RMA). The RMA polygons are a product of a script that uses inputs from the Forest Plan Riparian Standards and Guides Appendix D https://fs.usda.gov/Internet/FSEDOCUMENTS/stelprdb5367422.pdf, stream lines, soils, and lakes layers to define an initial riparian management area. The delineation methods for the RMA polygon feature have changed in response to changes in our GIS software. This document is the preliminary metadata for the next generation RMA product that meets the needs of the Forest Plan Riparian Standards and Guides Appendix D.History:The original RMA macro was written in 1998 and modified through 2002 by specialists in GIS, Botany and Hydrology. The final macro was titled RMA123 and was written in Arc Macro Language (AML). Changes in GIS software resulted in the model being rewritten in the scripting language Python and the original rationale revisited.Model ComponentsIn general the RMA direction states that the mapped RMA is the âgreatest of flood plain, riparian vegetation or soils or soils, riparian associated wetland fens or 1xx feet (the height of one site potential tree)â the site potential tree height varies by site and is tied to the stream process group. Streams supporting anadromous and resident fish (AHMU Classes 1 and 2) fall under the provisions of the Tongass Timber Reform Act (TTRA) and have a âNo Cutâ or TTRA buffer of 30 meters. In most cases, the mapped RMA is greater than 30 meters due to the site potential tree height provision. The model applies a buffer perpendicular to the stream line (assumed to be the stream centerline) to a distance that varies by its process group and AHMU class. The distance by which each classified channel is mapped is listed in a lookup table that is carried within the SEAKHydro Geodatabase. The lookup table (TLMP_StrmBuf) includes separate columns showing the buffer distance from channel centerline to the bank margin, side-slope length, TTRA buffer, no-cut buffer distance, and wind firm buffer distance.The soils layer has a lookup table that includes a riparian component. Riparian soils are flagged and added directly to the model output. Lakes greater than 3 acres in size are buffered by 30 meters.
Data and Resources
Start Date: 2013/08/12
End Date: 2013/08/27
Forest Fish, Hydrology Staff