TITLE OF THE DATA BASE A Coastal Hazards Data Base for the U.S. East Coast CONTRIBUTORS Vivien M. Gornitz National Aeronautics and Space Administration Goddard Institute for Space Studies 2880 Broadway New York, NY 10025 Tammy W. White Oak Ridge National Laboratory Environmental Sciences Division Oak Ridge, TN 37831-6335 SCOPE OF THE DATA The 29 data variables within A Coastal Hazards Data Base for the U.S. East Coast are designed for use by coastal planning, research, and management agencies in combination with appropriate climatological data (e.g., Birdwell and Daniels, 1991). The data base may be used to identify coastal zones that are vulnerable to coastal erosion and inundation from sea level rise or storm surge. This data base is comprised of the following data sets: elevation, bedrock geology, geomorphology, sea level trends, horizontal shoreline movements (erosion/accretion), tidal ranges, and wave heights. For several of these data sets minimum, mean, and maximum data values are available. These data variables may be divided into two basic classes, one that measures erosion potential and one that is related to inundation risk. The inundation risk of a given coastal grid cell may be estimated based on sea level trends and elevations; whereas the erosion risk may be determined based on geology, geomorphology, shoreline displacement, tidal ranges, and wave heights. Seven of the 29 data variables in this data base are classified versions of other variables within this data base. The seven classified risk variables contain "risk values" of one to five for each coastal grid cell in the data base. These risk variables may be used to calculate a Coastal Vulnerability Index (CVI) that may be used to identify areas on the East Coast that are vulnerable to sea level rise or coastal erosion. DATA FORMATS For ease of use, this data base has been divided into four data groups or coverages. The 22 original data variables have been provided in data group ECGRID (files ECGRID.E00 & ECGRID.ASC), the 7 relative risk variables have been provided in data group ECRISK (files ECRISK.E00 & ECRISK.ASC), and the source information for the tide and sea-level-trend data variables have been provided in the supplemental data group ECPOINT (files ECPOINT.E00 & ECPOINT.ASC). In addition, an auxiliary file with a 1:2,000,000 digitized coastline of the U.S. East Coast has been provided in ECOAST (files ECOAST.E00 & ECOAST.ASC). For the data groups identified above, two different data formats were used. Each format provides the data registered to a 0.25 degree latitude by 0.25 degree longitude grid [or in longitude/latitude coordinates in the case of ECPOINT (files ECPOINT.E00 & ECPOINT.ASC) and ECOAST (files ECOAST.E00 & ECOAST.ASC). The first format is designed for use by the ARC/INFO Geographic Information System (GIS). This format stores the data as points, arcs, or polygons (based on the coverage in question). The second format contains comparable data that has been converted into flat ASCII data files for use by raster GISs or non-GIS data base systems. For the data sets that were originally obtained as point data (i.e., sea level trends and tide ranges) the actual data variables, station names/numbers, record lengths, and latitude/longitude locations have been provided in data group ECPOINT. Within data group ECPOINT, data are provided on the basis of the data point, thus allowing the precise location of each station used in calculating the data for the 0.25 degree grid cells contained in ECGRID to be determined. A description of the contents of each of the data groups and files included with this data base follows: (1) ECGRID: Gridded polygon data for the 22 original data variables. Data sets contained in this file include elevation, geology, geomorphology, sea level trend, shoreline displacement, tide range, and wave heights. (2) ECPOINT: Point data for the stations used in calculating the sea-level-trend and tide-range data sets. Data include station names/numbers, record length, latitude/longitude location, and mean and maximum data values (when available). (3) ECRISK: Gridded polygon data for the seven classified risk variables. The risk variables are classified versions of the following original variables: mean coastal elevation, geology, geomorphology, local subsidence factor, mean shoreline displacement, mean tidal range, and the maximum significant wave height. (4) ECOAST: 1:2,000,000 digitized coastline of the U.S. East Coast. The coastline was extracted from a digitized map of the United States compiled by the U.S. Geological Survey. To improve the portability of the information in the data files, FORTRAN 77 input/output routines (*.FOR) and SAS input/output routines (*.SAS) have been included with this data base for each of the flat ASCII data files. These input/output routines are intended to be used to read/write the data values contained in the flat ASCII data files [containing the gridded data base, the original point data (for sea level trends and tide range), and the digitized coastline]. The FORTRAN 77 input/output routines were written to run on a SUN SPARC workstation under UNIX using SUN FORTRAN Version 1.3. Slight modifications to the routines may be necessary if running these codes on different platforms or under different operating systems. The data groups in this data base are available as exported ARC/INFO coverages (Version 6.0.1). The export files must be read into an ARC/INFO GIS using the IMPORT command with the COVER option after uploading the files onto a computer. These files are in a GEOGRAPHIC projection, which means the coverages are projected in a spherical reference grid using latitude and longitude coordinates that are stored in decimal degrees (DD). The flat ASCII files contain an identical version of this data base. The gridding method used in this data base consists of 7,040 0.25 degree latitude by 0.25 degree (o) longitude grid cells. These cells cover the area defined by the following coordinates: 85W, 24N; 85W, 46N; 65W, 46N; and 65W, 24N. The origin of the grid is at 85W, 24N, and grid identifiers increase from left to right, bottom to top. The data contained within each grid cell is valid for the entire grid cell. The data for a grid cell should not be construed as being representative of a "point" in the cell -be it the lower-left corner, upper-left corner, center, etc. The flat ASCII versions of the files have been provided to allow use of these data by users who do not have access to ARC/INFO. The format and contents of each of the flat ASCII files are described in the following section (the ARC/INFO coverages have the same variables and general format as described herein for the ASCII files). A line/arc version of the data in ECGRID and ECRISK is also provided here as an ARC/INFO coverage (i.e., ECLINE.E00). Coverage ECLINE contains 29 variables for each line segment in the coverage; these line segments average 4.5 km length, and when plotted, are equivalent to those found within the auxiliary file ECOAST. DATA GROUP ECGRID: This data group contains gridded polygon data for the 22 original data variables. These data variables are from the seven data sets and area as follows: minimum, mean, and maximum elevation, and the number of 5' grid cells used in deriving the data values; geology; geomorphology; relative sea level trend, long-term geologic-trend, corrected sea level trend, local subsidence trend, and the years of record of the gauge stations used in calculating these values; mean, minimum, and maximum shoreline displacement, and the number of 3', 7.5', or 15' grid cells used in deriving the data values; mean tide level, mean and maximum tidal range, and the number of tidal stations used in calculating these values; maximum significant wave height and the 20 year mean wave height and its standard deviation. The names of the ARC/INFO coverage and flat ASCII file in which these data variables reside are ECGRID.E00 and ECGRID.ASC, respectively. The file ECGRID.ASC is formatted as follows: 10 READ (5,100,END=999) ID, WHAVG, WHMAX, WHSD, ERAVG, 1 ERMAX, ERMIN, ERNUM, ELAVG, ELMAX, ELMIN, ELNUM READ (5,110) GM, GL, TRMAX, TRAVG, TRLVL, TRNUM, 1 SLR, SLG, SLC, SLS, SLYR 100 FORMAT(I5,6F8.2,I4,3F8.2,I4) 110 FORMAT(2I5,3F8.2,I4,4F8.2,I4) The variables in data group ECGRID (file ECGRID.ASC) are shown in Table 9 and are listed as they appear in the file. Table 9. Variable formats for ECGRID.ASC. Variable Column Variable Variable name start end type description ------------------------------------------------------------------------------ ID 1 5 Integer System variable - grid cell identifier WHAVG 6 13 Real Data variable - 20-year mean wave height experienced within each 0.25o grid cell; values in meters WHMAX 14 21 Real Data variable - maximum significant wave height for each 0.25o grid cell; values in meters WHSD 22 29 Real Data variable - standard deviation of the 20-year mean wave height experienced within each 0.25o grid cell; values in meters ERAVG 30 37 Real Data variable - mean long-term erosion trend for given 0.25o grid cell; values in meters ERMAX 38 45 Real Data variable - maximum long-term erosion trend for a given 0.25o grid grid; values in meters ERMIN 46 53 Real Data variable - minimum long-term erosion trend for a given 0.25o grid cell; values in meters ERNUM 54 57 Integer Data variable - number of 3', 7.5', or 15' grid cells used in calculating ERAVG, ERMIN, and ERMAX for a given 0.25o grid cell ELAVG 58 65 Real Data variable - mean elevation of all nonnegative 5' by 5' grid cells within a given 0.25o grid cell; values in meters ELMAX 66 73 Real Data variable - maximum elevation of all nonnegative 5' by 5' grid cells within a given 0.25o grid cell; values in meters ELMIN 74 81 Real Data variable - minimum elevation of all nonnegative 5' by 5' grid cells within a given 0.25o grid cell; values in meters ELNUM 82 85 Integer Data variable - number of 5' by 5' grid cells used in calculating ELAVG, ELMIN, and ELMAX for a given 0.25o grid cell --------------- SECOND LINE READS AS FOLLOWS ----------------- GM 1 5 Integer Data variable - ordinal value indicative of the type and susceptibility of the landforms within a given 0.25o grid cell to inundation and erosion GL 6 10 Integer Data variable - ordinal value indicative of the type and resistance of the rocks within a given 0.25o grid cell to erosion TRMAX 11 18 Real Data variable - maximum tide range measured for all gauge stations that occurred within a given 0.25o grid cell in 1988 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters TRAVG 19 26 Real Data variable - average of the mean tide range for all the gauge stations that occur within a given 0.25o grid cell (mean tide range is the difference in height between mean high water and mean low water in 1988); values in meters TRLVL 27 34 Real Data variable - the average of the mean tide levels of all the gauge stations that occur within a given 0.25o grid cell (mean tide level is a plane midway between mean low water and mean high water in 1988). Values were reckoned from chart datums (i.e., Gulf Coast Mean Low Water Datum was used for the Florida Keys; the Atlantic Coast Mean Low Water Datum was used for the rest of the East Coast) TRNUM 35 38 Integer Data variable - number of tide gauge stations used in calculating TRAVG, TRMAX, and TRLVL for a given 0.25o grid cell SLR 39 46 Real Data variable - relative sea level trend within a given 0.25o grid cell; values in mm/year SLG 47 54 Real Data variable - long-term geologic-trend derived from 14C data for each 0.25o grid cell; values in mm/year SLC 55 62 Real Data variable - corrected sea level trend. Tide-gauge data (i.e., SLR) corrected for geologic trends (i.e., SLG) for each 0.25o grid cell SLS 63 70 Real Data variable - the local subsidence trend. Tide-gauge data (i.e., SLR) corrected for the regional eustatic rate of sea level rise (i.e., 1.25 mm/year) SLYR 71 74 Integer Data variable - years of record used in estimating the sea level trend for each 0.25o grid cell ------------------------------------------------------------------------------ Within ECGRID missing data values are indicated as follows: 9999.99 - A grid cell with real data values that is missing data for a given data variable. 9999 - A grid cell with integer data values that is missing data for a given data variable. A value of 0.0 is a valid value for all variables. For the elevation variables 0.0 m indicates that land occurs within the given grid cell, but the maximum elevation of this land is < 1.0 m. If the data variables in a given data set, such as elevation, contain data and the "number" variable is set to zero (i.e., ELNUM, ERNUM, TRNUM, or SLYR), then the data variables for the given 0.25o grid cell have been estimated on the basis of the methods discussed in Part 1 of this document. DATA GROUP ECPOINT: This data group contains the point data for the stations used in calculating the relative sea level trend, long-term geologic-trend, corrected sea level trend, local subsidence factor, mean tide range, maximum tide range, and mean tide level variables contained within data group ECGRID. Data include station names, station number, record length, latitude/longitude location, and data variable values. The names of the ARC/INFO coverage and flat ASCII file are ECPOINT.E00 and ECPOINT.ASC, respectively. A summary of the format used for file ECPOINT.ASC follows: 10 READ (5,100,END=999) ID, SLLONG, SLLAT, SLR, SLG, 1 SLC, SLS, SLYR, SLNAME READ (5,110) TRLONG, TRLAT, TRAVG, TRMAX, TRLVL, 1 TRID, TRNAME 100 FORMAT(I5,6F8.2,I4,A38) 110 FORMAT(5F8.2,I5,A45) The variables listed in Table 10 are listed as they appear in data group ECPOINT (file ECPOINT.ASC). Table 10. Variable formats for ECPOINT.ASC. Variable Column Variable Variable name start end type description ------------------------------------------------------------------------------ ID 1 5 Integer System variable - Point identification number SLLONG 6 13 Real Data variable - longitude of the tide- gauge station used in determining the sea level trends SLLAT 14 21 Real Data variable - latitude of the tide- gauge station used in determining the sea level trends SLR 22 29 Real Data variable - relative sea level trend measured for each tide-gauge station; values are expressed in mm/year SLG 30 37 Real Data variable - long-term geologic-trend derived from C14 data; values are expressed in mm/year SLC 38 45 Real Data variable - corrected sea level trend. Tide-gauge data (i.e., SLR) corrected for long-term geologic-trends (i.e., SLG); values are expressed in mm/year SLS 46 53 Real Data variable - local subsidence trend. Relative sea level trend corrected for the regional eustatic rate of sea level rise (i.e., 1.25 mm/year) SLYR 54 57 Integer Data variable - years of record of the tide-gauge station used in determining the sea level trends SLNAME 58 95 Char Data variable - name of the tide gauge used for determining the sea level trends ----------------- SECOND LINE READS AS FOLLOWS -------------------- TRLONG 1 8 Real Data variable - longitude of a tide-gauge station used for determining the tide range variables TRLAT 9 16 Real Data variable - latitude of a tide-gauge station used for determining the tide range variables TRAVG 17 24 Real Data variable - difference between mean high water and mean low water for 1988; values in meters TRMAX 25 32 Real Data variable - maximum tide range, maximum measured range for the gauge station in 1988 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters TRLVL 33 40 Real Data variable - mean tide level, a plane midway between mean low water and mean high water in 1988. Values are reckoned from chart datums (i.e., Gulf Coast Mean Low Water Datum is used for the Florida Keys; the Atlantic Coast Mean Low Water Datum is used for the rest of the East Coast) TRID 41 45 Integer Data variable - station number (used in the 988 Tide Tables) of a tide-gauge station TRNAME 46 90 Char Data variable - name of a tide-gauge station (from the 1988 Tide Tables) ------------------------------------------------------------------------------ Within this data file, missing data values are indicated with one of the following values: 0.0 or 0 - A tide range or sea-level station that has not been assigned data for the variable in question. In this data group the sea level variables and tide range variables are mutually exclusive (i.e., if tide-range data are present, then the sea-level data are missing or vice versa). DATA GROUP ECRISK: This data group contains gridded polygon data for the seven classified risk variables. The risk variables are classified versions of the following original variables: mean coastal elevation, geology, geomorphology, local subsidence trend, mean shoreline displacement, mean tidal range, and maximum significant wave height. The names of the ARC/INFO coverage and flat ASCII file are ECRISK.E00 and ECRISK.ASC, respectively. A summary of the format used in file ECRISK.ASC follows: 10 READ(5,100,END=999) ID, 1 ERR, LSR, WHR, ELR, GMR, GLR, TRR 100 FORMAT(I5,7I4) The variables in data group ECRISK, listed in Table 11, are shown as they appear in file ECRISK.ASC. Table 11. Variable formats for ECRISK.ASC. Variable Column Variable Variable name start end type description ------------------------------------------------------------------------------ ID 1 5 Integer System variable - grid cell identifier ERR 6 9 Integer Data variable - classified version of the mean erosion/accretion variable (i.e., ERAVG) LSR 10 13 Integer Data variable - classified version of the local subsidence trend variable (i.e., SLS) WHR 14 17 Integer Data variable - classified version of the maximum significant wave-height variable (i.e., WHMAX) ELR 18 21 Integer Data variable - classified version of the mean elevation variable (i.e., ELAVG) GMR 22 25 Integer Data variable - classified version of the geomorphology variable (i.e., GM) GLR 26 29 Integer Data variable - classified version of the geology variable (i.e., GL) TRR 30 33 Integer Data variable - classified version of the mean tide range variable (i.e., TRAVG) ------------------------------------------------------------------------------ Values of Zero are used in risk variables to identify grid cells that are missing data for a given data variable. If several "no data" values occur within the same grid cell, then any calculated coastal vulnerability index that uses these relative risk factors may not accurately represent the risk of the given coastal area to sea level rise or coastal erosion (unless some type of corrective action is taken). Grid cells that are not in the coastal zone, or are totally ocean bound, have values of zero for all seven derived risk variables. AUXILIARY DATA GROUP, ECOAST: Auxiliary data group ECOAST (files ECOAST.E00 & ECOAST.ASC) contains a 1:2,000,000 digitized coastline of the U.S. East Coast. Data in this coverage were extracted from a digitized map of the United States (originally compiled by the U.S. Geological Survey). This coastline may be overlaid onto any of the three data groups previously discussed to provide locational information when plotting any or all of the data variables. Unlike the other data groups within this data base, this coverage contains line segments (or arcs) that describe the U.S. East Coast. The coastline provided has no attribute values associated with the line segments. However, such overlay commands as UNION, INTERSECT, and IDENTITY in ARC/INFO (or other GISs) may be used to transfer the gridded data values to the coastal segments, thus simplifying the interpretation of any derived indices. The name of the ARC/INFO coverage where the coastline resides is ECOAST.E00, and the flat ASCII data file with this same information is in ECOAST.ASC. Since this file is line based, the data values in ECOAST.ASC contain the line segment name, and a listing of the points that describe each line, for all 934 line segments that define the East Coast. The flat ASCII version of this file contains a listing of the line segments (or arcs) that describe the coast. An example of the format for this file is shown in Table 12. Table 12. Sample of the vector format used for ECOAST.ASC. Name, Number of points ------------------------------------------------------------------------------ "1", -5 -Vector 1 uses 5 points to describe the line -71.0812,45.1245 -Start at 71.08oW Longitude, 45.30oN Latitude -70.6414,45.4167 -70.9824,45.5545 -71.0035,45.6234 -71.0334,45.7834 -End of arc "2", -13 -Vector 2 uses 13 points to describe the line -71.0334,45.7834 -Start of next line -71.2267,45.7734 -71.2946,45.7948 ... -Continued ------------------------------------------------------------------------------ ARC/INFO is a registered trademark (TM) of the Environmental Systems Institute (ESRI), Inc., Redlands, CA 92372. SAS is a registered trademark of the SAS Institute, Inc., Cary, NC 27511-8000. END OF FILE