Unpaved roads can be the dominant source of land-use related sediment pollution in forested landscapes in the U.S. with impacts to water quality and aquatic biota. NetMap Portal contains a series of analyses that help identify which road segments are most likely to create sediment pollution and deliver it to the channel network. The new Road Erosion and Sediment Delivery Index model is used in NetMap; for additional information, go here.

 

If these attributes are not available for your own watershed, please contact us.

 

Using information on road-stream crossings and natural drainage points (e.g., low spots along roads), and in certain applications, GPS points for all engineered drains, and information on road surfacing types (paved, gravel, native soil), READI is used to predict sediment production on the road and more importantly sediment delivery. NetMap uses a dimensionless index for erosion and sediment delivery rather than units of mass per time (tons per year) given the great uncertainty in predicting erosion. The aim is to identify those road segments with the greatest potential to deliver sediment to streams, for prioritizing road maintenance and improvements. For additional information, go here.

 

 

 

Figure 1. READI conceptual framework is based on a design storm with an assigned duration and intensity that produces road runoff (carrying sediment) that either is delivered directly to a stream at a road-stream intersection or indirectly to a stream via the forest floor at a natural or engineered drain location.

 

 

 

(Left) Predicted sediment production - all unpaved road surfaces produce sediment. (Right) Only a small percentage of road segments delivers sediment to streams, with the red lines being the most significant. This prediction could be used to prioritize road maintenance and improvements.