Coastal Shoreline Condition (Southeast Blueprint Indicator)

Reason for Selection Human development along shorelines, along with jetties, groins, seawalls, revetments, and other structures, provide a measure of overall habitat alteration and shoreline condition. Human infrastructure along shorelines generally stabilizes barrier islands, impeding natural beach migration and barrier island rollover processes. Groins, seawalls, jetties, and revetments have resulted in narrowing of beaches, or greater beach loss, compared to unstructured beaches (Dugan et al. 2008, Hall and Pilkey 1991, Mohanty et al. 2012, Pilkey and Wright III 1988). Jetties also alter sand transport and may result in downdrift erosion (Bruun 1995). Hardened structures landward of tidal wetlands can cause “coastal squeeze” by accelerating erosion during storms and preventing inland migration in response to sea-level rise (Gittman 2015). In addition, hardened shorelines, particularly seawalls, generally support lower levels of biodiversity (Gittman et al. 2015, 2016). Studies funded by NOAA’s National Centers for Coastal Ocean Science found that shoreline hardening has a negative impact on amounts of submerged aquatic vegetation (SAV) and on fish density and egg-laying (NOAA NCOS 2015, 2013). Input Data * National Oceanic and Atmospheric Administration (NOAA) [Environmental Sensitivity Index] (ESI) [National Shoreline dataset]: This dataset classifies shorelines into types of natural habitat and hardened structures to identify coastal resources that are at risk if an oil spill occurs nearby. * Spatial designations of the [Coastal Barrier Resources System] (CBRS), as a result of the Coastal Barrier Resources Act (1982) and subsequent amendments (last updated 3-15-2019), accessed 1-31-2022 The CBRS was used to set boundaries of relatively undeveloped coastal areas that are more difficult to develop. The Act incentivizes the conservation of mostly intact coastal barrier landforms—such as barrier islands, beaches and dunes, fringing mangroves, and others—to protect valuable natural resources and minimize the loss of human life and property due to hurricanes. It restricts federal expenditures that encourage development in these areas, such as flood insurance. * [Base Blueprint 2022 extent] * [Southeast Blueprint 2023 extent] Mapping Steps * Convert the CBRS polygons to a 30 m raster. Partially armored and natural shoreline pixels will receive a bump in their score if they fall within a CBRS polygon. * From the ESI data, extract saline estuarine shorelines, where LINE field is not ‘H’ and ENVIR field is ‘E’. * The GENERALIZED_ESI_TYPE field contains 1-3 shoreline types, listed landward to seaward. If the field contains only ‘1: Armored’, consider it fully armored and assign it the lowest value (0) in the indicator. * If GENERALIZED_ESI_TYPE contains multiple shoreline types and any of them are armored, consider it partially armored. Assign these pixels a value of 1 (if they are outside the CBRS) or 2 (if they are inside the CBRS) in the indicator. * Consider all other GENERALIZED_ESI_TYPE fields as natural shoreline. Assign them values of 3 (if they are outside the CBRS) or 4 (if they are inside the CBRS) in the indicator. * Convert the entire ESI linework to a 30 m raster. * Clip to the spatial extent of Base Blueprint 2022. * As a final step, clip to the spatial extent of Southeast Blueprint 2023. Note: For more details on the mapping steps, code used to create this layer is available in the [Southeast Blueprint Data Download] under > 6_Code. Final indicator values Indicator values are assigned as follows: 4 = Natural and harder to develop 3 = Natural 2 = Partially armored and harder to develop 1 = Partially armored 0 = Armored Known Issues * This indicator overestimates shoreline condition in areas near hardened structures. It only predicts low values in places that are currently hardened and not in nearby areas that can also be impacted by that hardening. * This indicator overestimates shoreline condition in areas with active beach renourishment. Beach renourishment negatively affects some beach and dune species but is not captured by this indicator. * This indicator does not take into account protected natural areas (e.g., National Wildlife Refuges such as St. Marks in Florida) that are unlikely to be developed but are not within the CBRS. * In areas where source data is outdated, this indicator sometimes overestimates shoreline condition because it does not capture more recent shoreline alteration (such as the addition of new residential docks and boat slips along the Texas coast). This dataset is a compilation of individual state inputs that vary in age, ranging back to 1996. Some states, like Florida and Texas, maintain their own ESI data separate from the national NOAA ESI, but differences in data structure and formatting made it difficult to combine those with the national ESI data this year. We hope to incorporate more recent state data in future Blueprint updates. Disclaimer: Comparing with Older Indicator Versions There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email [hilary_morris@fws.gov]). Literature Cited Bruun, P., 1995. The development of downdrift erosion. J. Coast. Res., 1242-1257. [[https://www.jstor.org/stable/4298427]]. Dugan, J.E., Hubbard, D.M., Rodil, I.F., Revell, D.L., Schroeter, S., 2008. Ecological effects of coastal armoring on sandy beaches. Marine Ecology 29, 160-170. [[https://onlinelibrary.wiley.com/doi/full/10.1111/j.1439-0485.2008.00231.x]]. Gittman, R.K., Fodrie, F.J., Popowich, A.M., Keller, D.A., Bruno, J.F., Currin, C.A., Peterson, C.H. and Piehler, M.F. (2015), Engineering away our natural defenses: an analysis of shoreline hardening in the US. Frontiers in Ecology and the Environment, 13: 301-307. [[https://doi.org/10.1890/150065]]. Gittman, Rachel K., Steven B. Scyphers, Carter S. Smith, Isabelle P. Neylan, Jonathan H. Grabowski, Ecological Consequences of Shoreline Hardening: A Meta-Analysis, BioScience, Volume 66, Issue 9, 01 September 2016, Pages 763-773. [[https://doi.org/10.1093/biosci/biw091]]. Hall, M.J., Pilkey, O.H., 1991. Effects of hard stabilization on dry beach width for New Jersey. J. Coast. Res., 771-785. [[https://journals.flvc.org/jcr/article/view/78532/75937]]. Mohanty, P.K., Patra, S.K., Bramha, S., Seth, B., Pradhan, U., Behera, B., Mishra, P., Panda, U.S., 2012. Impact of groins on beach morphology: a case study near Gopalpur Port, east coast of India. J. Coast. Res. 28, 132-142. [[https://bioone.org/journals/journal-of-coastal-research/volume-28/issue-1/JCOASTRES-D-10-00045.1/Impact-of-Groins-on-Beach-Morphology--A-Case-Study/10.2112/JCOASTRES-D-10-00045.1.full]]. National Oceanic and Atmospheric Administration Office of Response and Restoration, Seattle, Washington. May 2017. National Environmental Sensitivity Index Shoreline: GULF/ATLANTIC ESI: ESI Shoreline Types – Lines. [[https://response.restoration.noaa.gov/esi_download]]. National Oceanic and Atmospheric Administration National Centers for Coastal Ocean Science. August 10, 2015. Hardened Shorelines Make it Hard for Submerged Aquatic Vegetation. [[https://coastalscience.noaa.gov/news/hardened-shorelines-make-hard-submerged-aquatic-vegetation/]]. National Oceanic and Atmospheric Administration National Centers for Coastal Ocean Science. January 23, 2013. Project Finds Fish Prefer Natural Shorelines. [[https://coastalscience.noaa.gov/news/riprap-project-finds-fish-prefer-natural-shorelines-human-response-to-sea-level-rise-at-issue/]]. U.S. Fish and Wildlife Service. March 2019. John H. Chafee Coastal Barrier Resources System Approximate Polygons Vector Digital Dataset. Falls Church, VA. Accessed January 31, 2022. [[https://www.fws.gov/program/coastal-barrier-resources-act/maps-and-data]]. Pilkey, O.H., Wright III, H.L., 1988. Seawalls versus beaches. J. Coast. Res., 41-64. [[https://www.jstor.org/stable/25735351]]. Rice, T.M., 2012a. Inventory of Habitat Modifications to Tidal Inlets in the Continental U.S. Coastal Migration and Wintering Range of the Piping Plover (Charadrius melodus). Appendix 1b, in Comprehensive Conservation Strategy for the Piping Plover (Charadrius melodus) in its Coastal Migration and Wintering Range in the Continental United States. U.S. Fish and Wildlife Service, East Lansing, Michigan.