A hybrid approach for incorporating high resolution LIDAR DEMs into USGS StreamStats at the state level

Authors: Daniel Warner*, Delaware Geological Survey, Beatrice O'Hara, Delaware Geological Survey, John Callahan, Delaware Geological Survey
Topics: Water Resources and Hydrology, Environmental Science, Transportation Geography
Keywords: watershed, GIS, DEM, topography, streams
Session Type: Poster
Day: 4/4/2019
Start / End Time: 9:55 AM / 11:35 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: Download

The increasing availability of high-resolution LIDAR data across the United States has allowed researchers to examine surface topography with unprecedented detail. This is particularly beneficial for GIS-based surface hydrologic applications, as fine scale elevation data may reveal previously unmapped streams, ditches, and impediments to flow. The Delaware Geological Survey has utilized high resolution LIDAR data collected in 2014 to update USGS StreamStats application for the state of Delaware. USGS StreamStats is a valuable online, map-based tool for water resource management and engineering design, which allows users to obtain peak streamflow statistics at any location along a gaged or ungaged stream.

A “hybrid” approach was employed, combining existing National Hydrography Dataset (NHD) features and LIDAR-derived DEMs. First, the LIDAR DEM was conditioned and enforced to allow flow over erroneous depressions and through culverts. Next, stream derivation algorithms and aerial photographs were used to identify surface drainages that were not included in the NHD. In some cases, these NHD “extensions” extended beyond the previous watershed delineations. Finally, the conditioned DEM and newly derived stream network were put through the StreamStats workflow to delineate new gage basin boundaries. Numerous basin characteristics were derived and used as spatial covariates in StreamStats regression equations to compute peak flow statistics. This project highlights the potential benefits of using a hybrid approach for other states seeking to update their flood statistics in USGS StreamStats, and addresses several obstacles encountered along the process.

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