Riparian Function Assessment: Running the Tool
Tool Summary
Inputs:
- Stream Reach feature class with or without waterbody merged (Use same input at the last two steps; StreamReach + inHUC or StreamReachWB + inHUC) (Required)
- Riparian Catchments (RiparianCatchments + inHUC) (Required)
- Height Above Channel raster (HAC + inHUC) (Required)
Outputs:
- Riparian Function Assessment table (RiparianFunction + inHUC)
Denitrification Potential Rank
The classification of riparian zones based on width of low-lying land characterizes the natural capacity for a riparian zone to provide water-quality benefits through denitrification. Riparian zones with a wide zone of low-lying land present opportunities to consistently influence groundwater with a widened buffer that includes deep-rooted vegetation, leading to this classification of riparian sites.
High: Low-lying land (<1.5m height above channel) extends on average to distances greater than 50 meters from the stream
Medium: Low-lying lands extends on average to distances between 25 and 50 meters from the stream
Low: Low-lying land extends on average to distances less than 25 meters from the stream
Runoff Delivery Rank
The classification of riparian zones based on local runoff delivery identifies where a significant potential for runoff contribution exists, to show where buffer vegetation should be widened to at least 10 meters, and to include stiff-stemmed grasses to effectively intercept runoff, leading to this classification of riparian sites:
High: Riparian zones that have the greatest potential to receive overland flow, and that would convey half the surface runoff from the watershed that contribute to the stream, if all areas were to generate runoff equally. Riparian management in these sites should often be extended to include conservation treatments on ephemeral waterways that are up-gradient.
Medium: Riparian zones where a buffer occupying 2 percent of the mean flowpath length (size of riparian catchment/straight line length of riparian segment) is greater than 10 meters.
Low: A 10-meter-wide (or narrower) buffer provides the minimum recommended buffer area ratio of 0.02. In this class, the buffer widths required for bank stabilization and for runoff interception are similar.
Once the cross-classification is applied, buffer widths are recommended for each riparian design ranging in size from 6 meters wide to 50 meters.
Riparian Function Table Attributes
| Attribute | Description |
|---|---|
| Riparianid | Unique identifier x_y_z designating stream reach (x), riparian segment counter along to the reach (y), and side of stream (z) |
| Wdthlt1_5 | Average width of low height above channel elevations (<1.5 meters) within the riparian zone of each riparian catchment |
| len_met | Actual length of the stream (in meters) along each unique riparian section of the stream reach. |
| sl_len | Straight line distance (in meters) along each unique riparian section of the stream reach |
| Ratio_10m | Ratio of the area of a 10-meter buffer (2500 m^2) divided by local runoff. NRCS guidelines suggest an area/runoff ratio of at least 0.02 and wider buffers are suggested for ratios <0.02 |
| RunoffRank | Runoff Delivery Rank: High, Med, or Low |
| DenPotRank | Denitrification Potential Rank (based on width of low-lying land): High, Med, or Low |
| Function | Riparian Buffer Design Type |
| NRCSWidth | Suggested buffer width according to the NRCS (in meters) |
| BuffWidth | Suggested buffer width using ACPF guidelines (in meters) |
For more information on running this tool, please watch this video.
Runtime: 6:20