Interactive Map of Streams Intersecting Tuscarora Formation


       This map shows NHD flowline segments that intersect the Tuscarora Formation. This geologic formation has been shown to be susceptible to atmospheric deposition due to extremely low buffering capacity of parent material (Kirby et al., 2008). Streams in drainages < 20 sq. mi. are also at increased risk for atmospheric deposition. The map shows both the Tuscarora Formation and stream segments symbolized by size (less than /greater than 20 sq. mi.).
       This map is intended to aid data collection. Small streams underlain solely by the Tuscarora Formation are anticipated to be at increased risk for impairments due to atmospheric deposition.




Literature Justification

  • A study of atmospheric deposition in the ridge and valley province in central Pennsylvania determined that streams draining the Tuscarora Formation had inferior buffering capacity, lower pH, and higher dissolved aluminum concentrations compared to adjacent sandstone formations (Kirby et al., 2008).


  • The 2020 Integrated Report Viewer https://www.depgis.state.pa.us/IRViewer2020/ was accessed to download metatdata for all stream segments that are currently impaired for source ‘Atmospheric Deposition’ and all causes. This resulted in 1,540 stream segments that ranged in drainage area from 0.001 – 68.8 mi2, with a median of 0.5 sq. mi. The 99th percentile of drainage sizes for this population of streams was 19.4 sq. mi., meaning streams less than ~ 20 sq. mi are at the highest risk for impairments due to atmospheric deposition.


  • Kirby et al. (2008) found evidence that limestone gravel roads that run parallel to streams may potentially increase pH alkalinity of adjacent streams. This evidence was not conclusive in their study, but the mechanism has a solid foundation and should be examined further in future data collections and analysis.



Analytical Methods


  • The geology (bedrock) layer from GNET was accessed and a definition query was established where NAME = ‘Tuscarora Formation’.
    • This resulting shapefile was exported and used in the interactive map above.
  • The NHD flowline from GNET was added to the ArcMap project, and stream segments were selected when a segment intesected the Tuscarora Formation
    • This resulted in a selection of 1,038 stream segments, which was exported as a new shapefile. The result is included in the map above
  • The NHD Plus HR ‘Permanent_Identifier’, ‘StreamOrde’, ‘TotDASqKM’, ‘MaxElevSmo’, ‘MinElevSmo’, and ‘Slope’ attributes associated with each stream segment were joined to the above selection, and are included in pop-up boxes that are shown in the above map to aide data collection.
    • Attributes from 9 stream segments were not available from the NHD Plus HR dataset.



Utility

       The map included herein will serve as a valuable screening tool to identify locations where data collection is warranted to refine Pennsylvania’s atmospheric deposition source/cause determination protocol (Friday, 2000).



Literature Cited

Driscoll, C.T., G.B. Lawrence, A.J. Bulger, T.J. Butler, C.S. Cronan, C. Eagar, K.F. Lambert, G.E. Likens, J.L. Stoddard, and K.C. Weathers. 2001. Acidic Deposition in the Northeastern United States: Sources and Inputs, Ecosystem Effects, and Management Strategies. BioScience 51(3):180-198.

Friday, M. 2000. Acid Precipitation Source and Cause Determination Method. Chapter 6, pages 6-10. In Shull, D. R., and M. M. Pulket. (editors). Assessment methodology for streams and rivers. Pennsylvania Department of Environmental Protection. Harrisburg, Pennsylvania.

Kirby, C.S., B. McInerney, and M.D. Turner. 2008. Groundtruthing and potential for predicting acid deposition impacts in headwater streams using bedrock geology, GIS, angling, and stream chemistry. Science of the Total Environment 393:249-261.