FWS_NE_Impoundments_polygons

From the grant report - EasyGrantsID: 42878 National Fish and Wildlife Foundation – Hurricane Sandy Coastal Resiliency Competitive Grants Program 2013 Title: Assessing Coastal Impoundment resilience and vulnerability in the Northeast. November 2, 2015 Refer correspondence to: Nellie Tsipoura New Jersey Audubon Society 11 Hardscrabble Road Bernardsville, NJ 07924 Cell phone (732) 310-1348 E-mail: nellie.tsipoura@njaudubon.org Coastal impoundments can be the first line of defense for communities against coastal storms and sea level rise. Many also provide habitats for important animal populations and communities, such as migratory and breeding birds and breeding and rearing areas for fish and crustaceans. Many northeastern impoundments are no longer able to resist storms and several failed during superstorm Sandy, with catastrophic societal and ecological consequences. This project will categorize all of the Northeastern impoundments in terms of their importance in reducing the risks of inundation to adjacent communities, their ecological value, and their vulnerabilities to future storm events and sea level rise. It will also identify restoration options that will enhance the resilience of vulnerable impoundments to sea level rise and future storm events. Objectives Coastal impoundments are often the first line of defense for adjacent communities in Mid-Atlantic and Northeast coastal areas against the impacts of storms, tidal surges and, most recently, rising sea levels. Without such defenses, as unfortunately demonstrated during superstorm Sandy, local communities across the region could be at far greater risk from rising sea levels and more severe storm events. Furthermore, in addition to protecting human communities, many impoundments are also of great importance for the ecological resources that they sustain. These include populations of breeding and migratory birds, and crustacean and fish spawning and rearing areas. For societal and ecological reasons, therefore, it is vital that we safeguard coastal impoundments in an era of changing climate. Under the rapidly changing circumstances described above, and in the aftermath of superstorm Sandy, it is vital that managers and planners at the federal, state, and local levels benefit from gaining a better understanding of: 1. Which impoundments provide the most protection to coastal communities from storms and sea-level rise 2. Which impoundments sustain significant ecological resources 3. Which are most vulnerable to future damage and failure and which may inevitably transition to different habitats 4. Which should be a priority for restoration and protection, given their risk reduction and ecological values, and the management investment needed to maintain them Approaches To get a better understanding of impoundments and develop the management recommendations, we will develop several products through literature review, mapping, and field measurements. Specific products will include: 1) comprehensive GIS Catalog and map of coastal impoundments from Virginia to Massachusetts. This will detail information such as location, size, elevation, proximity to human communities, and hydrological features of each of the coastal impoundments in the study area. The catalog will also include spatial information from a Societal Risk, Ecological Value, and Climate Vulnerability Assessment 2) Societal Importance, Ecological Value, and Climate Vulnerability Assessment: This will include an analysis of each northeastern impoundment in terms of (a) the protection that it confers on coastal human communities, from storms and sea-level rise (b) its ecological functions and values, and (c) its vulnerability to future storms and sea-level rise. From these data, priority impoundments will be identified based on their ability and/or potential to reduce risk to communities, and to conserve important ecological communities and habitats. The objective of this document is to identify the quality assurance components that are necessary to implement the project activities under the “Assessing Coastal Impoundment resilience and vulnerability in the Northeast”. This objective will be achieved by mapping impoundments, incorporating National Wetlands Inventory data, and other information pertinent to these impoundments, and measuring embankment width, height, and freeboard from Lidar topography and NOAA data, as outlined below. Creating the coastal impoundment catalog, literature database, and map We will compile a complete list of coastal impoundments from Maine to Virginia along with geographic coordinates and attribute information relevant to ecological value, vulnerability, and coastal resiliency. ‘Coastal impoundment’ are defined as an impounded (usually diked) area adjacent to tidal waters, within which water levels are actively managed to benefit wildlife. We will begin our search by systematically browsing through all coastal state wildlife area and National Wildlife Refuge web pages within the study area. This list will be supplemented by conducting a formal literature search in Web of Science, Google Scholar, and Google web search. Any scholarly papers, reports, presentations, or web resources that related to managed coastal impoundments within the study area will be retained. References will be entered into an online RefWorks database, which is exportable to multiple formats, searchable, and organized into folders by and local grouping. Following the information provided, photo-interpreters will locate and delineate each impoundment in ESRI’s ArcGIS 10.1. Mapping will be completed at a scale of 1:8000 with a Target Mapping Unit (TMU) of .25 acres using publically available orthophotos provided by each state. The boundaries of the resulting impoundments will be delineated within ArcGIS, using spatial data from the most recent (2011 or later) National Wetlands Inventory (NWI) as a basis for the boundaries. Boundaries will be manually modified as needed to conform with information from refuge maps or other sources. Methods and techniques utilize protocols developed to update wetland maps for the USFWS’s (NWI). This means all mapping meets or exceeds Federal Geographic Data Committee (FGDC) wetlands mapping standards and protocols (https://www.fgdc.gov/standards). The National Wetlands Inventory data for the area within each impoundment will be extracted as a separate GIS file so that information on features such as wetland type, hydrology, salinity, and vegetation cover would be readily available. Using the sources obtained in the literature search, and existing ecological data such as SHARP, ISS, IWMM, we will compile a variety of ecological, physical, and historical data on each impoundment and cluster of impoundments. We will also conduct interviews using the attached questionnaire (Appendix B) to obtain any additional information from site managers about the impoundments, that may not be available in reports. This information will be spatially linked to and retrievable from each impoundment within the GIS database. Descriptors such as impoundment area will be calculated in the GIS while distances to nearby structures will measured manually. All attributes found in the literature review will be also imported into the GIS and the records added to the appropriate impoundment. Senior PIs will review all maps to confirm and document mapping accuracy and to ensure the final impoundment map meets or exceeds all standards outlined above. Lidar-based vulnerability measurements We will download Lidar-based elevation data for each cluster of impoundments from respective state websites (attached in the references section) in 2-foot contour format, or convert into this format from raster data when provided. Contours will then be converted into TIN (triangulated irregular network) format for analysis. The centerline of each berm adjacent to tidal waters will be digitized as a separate polyline shapefile. Perpendicular transects will be generated along this line using an ArcGIS add-in tool (“Transect 2.0”) with a spacing of 200 m between transects. For berms less than 600 m long, we will measure at least three transects per berm by using a spacing of the berm’s length divided by three. At each transect, we will generate a two dimensional cross-section of the berm based on the TIN surface using the ArcGIS extension “Crossview for ArcGIS”. At each berm cross-section we will measure the top width, defined as the breadth of the flattened top portion of the berm (Figure 1). At the three locations with the narrowest top width for each impoundment we will perform a series of more detailed measurements of the cross-sections. These are: 1) elevation above sea level of the exterior and interior toes of the slopes and the top of the berm, and 2) horizontal width of the exterior and interior slopes (see Figure 1). The average percent slope of the exterior and interior banks will be calculated as follows: [(berm elevation) - (toe of slope elevation)] / (slope width). Freeboard, or elevation relative to mean high water (MHW) rather than to mean sea level (MSL), will be calculated by using a stand-alone program published by the National Oceanic and Atmospheric Administration (“vdatum”) to determine the local difference between MHW and MSL. This difference will be subtracted from berm elevation to obtain freeboard.