Silver Jackets Project - Chattahoochee River in Helen, Georgia (General)

The purpose of this project was to complete Flood Forecast Inundation Mapping (FFIM) for a reach of the Chattahoochee River through the city of Helen, Georgia. The FFIM project submittals include a geo-referenced HEC-RAS hydraulic model and geo-referenced inundation polygons and depth grids. In addition to this main data submittal, base and supplemental data are required to accompany the mapping products for proper documentation and implementation of the flood mapping outputs. The reach was modeled with 1-D, steady flow hydraulic modeling software, utilizing geo-referenced stream parameters and a 2-m LiDAR dataset. These data will be provided to the National Weather Service (NWS) of the National Oceanic and Atmospheric Association (NOAA) for potential implementation onto the Advanced Hydrologic Prediction Service (AHPS) web interface and connected with the river forecast for HDCG1.

The project area is located in the city of Helen, Georgia, which lies in north-central White County and the Chattahoochee River Watershed. The county is bordered by Towns County to the north, Union and Lumpkin Counties to the west, Habersham County to the east, and Hall County to the south. The project area encompasses an approximate 5.25-mile reach of the Chattahoochee River, beginning at a location approximately 7,600 feet upstream of the Helen, GA corporate limits, and ending at a location approximately 5,800 feet downstream of the Helen, GA corporate limits.

NWSLID: HDCG1
Latitude: 34.700833° N, Longitude: 83.729444° W, Horizontal Datum: NAD83/WGS84

本项目的宗旨在于完成乔治亚州海伦市一段查塔胡其河的洪水预报淹没映射（FFIM）。该FFIM项目的提交文件包括一个地理参照的HEC-RAS水力模型、地理参照的淹没多边形和深度网格。除此之外，为了确保洪水映射输出的正确记录和实施，还需提供基础和补充数据。该河段通过一维、稳态流水力建模软件进行模拟，利用地理参照的溪流参数和2米分辨率的LiDAR数据集。这些数据将被提供给国家海洋和大气管理局（NOAA）的国家气象服务（NWS），以供在高级水文预测服务（AHPS）网络界面上的潜在应用，并与HDCG1的河流预报相连接。项目区域位于乔治亚州海伦市，地处白县东北部，查塔胡其河流域。该县北部与汤斯县接壤，西部与联合县和卢姆皮县相邻，东部与哈伯斯姆县相邻，南部与霍尔县毗邻。项目区域覆盖了查塔胡其河约5.25英里的河段，起始点位于海伦市公司界限上游约7,600英尺处，终止点位于海伦市公司界限下游约5,800英尺处。
NWSLID: HDCG1
纬度：34.700833°北，经度：83.729444°西，水平基准：NAD83/WGS84