FEMA - Harvey Flood Depths Grid

This resource describes a dataset of gridded depth at horizontal resolution of 3 meters, published as an Esri ArcGIS geodatabase on November 15, 2017 by FEMA. This dataset is no longer accessible from FEMA, but is now uploaded to this HydroShare resource in the contents list. This product utilized Triangulated Irregular Network (TIN) interpolation, four quality assurance measures (identifying dips, spikes, duplication, and inaccurate/unrealistic measurements). High Water Marks were obtained from the Harris County Flood Control District (HCFCD), US Geological Survey (USGS), and other inspection data. Elevation data comprised a mosaic of 3 meter resampled elevations from 1M & 3M LiDAR, and IFSAR data. One section of the IfSAR data was found to be erroneous, and replaced with a blended 10 meter section.
[This method description was from correspondence January 22, 2018, from Mark English, GeoSpatial Risk Analyst, FEMA Region VIII, Mitigation Division.]

See FEMA's Natural Disasters data site [1] for additional HWM-based depth grids and inundation polygons:
- Harris County Areas of Interest (AOIs) and Inundation Boundaries
- Harris County Depth Grids
- Aransas, Nueces, and San Patricio Coastal Depth Grids and Boundaries

Some of the data available below in the contents list is from the FIMA NHRAP program, which is no longer available from FEMA, as of the summer of 2019.

FEMA notes on these Modeled Preliminary Observations:
o Based on observed Water Levels at stream gauges interpolated along rivers, downsampled to 5m resolution DEM
o Depth grids updated with new observed peak crest as they become available
o Will include High Water Mark information as it becomes available
o Extents validated with remote sensing
o Use for determining damage levels on specific structures

References:
[1] FEMA Harvey data [https://disasters.geoplatform.gov/publicdata/NationalDisasters/2017/HurricaneHarvey/Data/] [link is no longer accessible]