Cumulative Risk of Flow Alteration from Impervious Surfaces in the SARP Region

The SARP Flow Alteration Assessment provides a regional characterization of the distribution and risk of flow regime impairment of streams and rivers by anthropogenic sources at the NHD+ segment scale. This map illustrates the cumulative risk of flow alteration (RFA) due to runoff from impervious surfaces for the 14-state SARP region.  The amount of impervious surface is based on 2006 National Land Use/Land Cover dataset.  The risk is based on the percentage of the catchment land surface covered by impervious surfaces (100 x impervious surface area / watershed surface area):

Risk of flow alteration categories:
                            ZERO -      0% land covered by impervious surface
                            LOW -    < 5%
                            MEDIUM - 5-20%
                            HIGH -       >20%
 


The map is scaled to illustrate larger rivers at the regional scale.  Zoom in to add small and medium rivers at the state scale and all streams and rivers at the county scale.
 
The Flow Alteration Assessment was developed in collaboration with regional aquatic ecologists from the South Atlantic and Gulf Coast Prairie LCCs.  For more information about the risk of flow alteration assessment and how this map was developed for the Southern Instream Flow Network (SIFN), go to the SIFN Instream Flow Resources web page.  For state summaries of flow alteration by river size class, see the attachment tab below.
 
Your comments about this map and the databases are welcome.  Please send comments to the map author using the Comment tab below.