Coastline Analysis by Subregion and Subbasin: The coastline is a difficult feature to maintain in the NHD. In the Gulf coast area, every hurricane that blows through the area rearranges the coastline, sometimes dramatically! In addition, most of the coastline in the NHD has not been updated to newer imagery, rather most coastlines in the NHD are represented as shown on the older topographic maps. In some cases this information may be 20 – 25 years old. The following calculations were generated using ArcMap version 9.3, service pack 1. NHD data was downloaded from the USGS High Resolution FTP download site (). The NHD data was loaded into a new ArcMap session, the NHDFlowline table was opened, and a query was built searching for every feature representing a coastline. The selected features were then queried through a field named ‘LengthKM’ to determine the total length of the coast in each subregion and in each subbasin. Subbasins that did not contain any coastline features are not listed. The conversion factors used: 1.609 km/statue mile and .6214 statute mile/km. In all cases, a Geographic project in North American Datum (NAD) 1983 was used to calculate all distances and areas. This is the native projection/datum for NHD. 0317 – Pascagoula Coastline features LengthKM Statute Miles 1,364 1,050.041 km 652.495 miles 03170006 Coastline features LengthKM Statute Miles 32 25.2 km 15.659 miles 03170009 Coastline features LengthKM Statute Miles 1,332 1,024.841 km 636.836 miles 0318 – Pearl Coastline features LengthKM Statute Miles 17 15.778 km 9.804 miles 03180004 Coastline features LengthKM Statute Miles 17 15.778 km 9.804 miles 0808 – Louisiana Coastal Coastline features LengthKM Statute Miles 692 841.417 km 522.856 miles 08080101 Coastline features LengthKM Statute Miles 142 154.723 km 96.145 miles 08080102 Coastline features LengthKM Statute Miles 128 65.276 km 40.563 miles 08080103 Coastline features LengthKM Statute Miles 384 446.043 km 277.171
Coastline Analysis by Subregion and Subbasin: The coastline is a difficult feature to maintain in the NHD. In the Gulf coast area, every hurricane that blows through the area rearranges the coastline, sometimes dramatically! In addition, most of the coastline in the NHD has not been updated to newer imagery, rather most coastlines in the NHD are represented as shown on the older topographic maps. In some cases this information may be 20 – 25 years old. The following calculations were generated using ArcMap version 9.3, service pack 1. NHD data was downloaded from the USGS High Resolution FTP download site (). The NHD data was loaded into a new ArcMap session, the NHDFlowline table was opened, and a query was built searching for every feature representing a coastline. The selected features were then queried through a field named ‘LengthKM’ to determine the total length of the coast in each subregion and in each subbasin. Subbasins that did not contain any coastline features are not listed. The conversion factors used: 1.609 km/statue mile and .6214 statute mile/km. In all cases, a Geographic project in North American Datum (NAD) 1983 was used to calculate all distances and areas. This is the native projection/datum for NHD. 0317 – Pascagoula Coastline features LengthKM Statute Miles 1,364 1,050.041 km 652.495 miles 03170006 Coastline features LengthKM Statute Miles 32 25.2 km 15.659 miles 03170009 Coastline features LengthKM Statute Miles 1,332 1,024.841 km 636.836 miles 0318 – Pearl Coastline features LengthKM Statute Miles 17 15.778 km 9.804 miles 03180004 Coastline features LengthKM Statute Miles 17 15.778 km 9.804 miles 0808 – Louisiana Coastal Coastline features LengthKM Statute Miles 692 841.417 km 522.856 miles 08080101 Coastline features LengthKM Statute Miles 142 154.723 km 96.145 miles 08080102 Coastline features LengthKM Statute Miles 128 65.276 km 40.563 miles 08080103 Coastline features LengthKM Statute Miles 384 446.043 km 277.171
GulfCoast_NHD_Assess_27May2010.docx