Evaluation and Development of National Aeronautic and Space Administration's (NASA) Experimental Advanced Airborne Research Light Detection and Ranging (LiDAR) (EAARL) for Accurate Representation of High Resolution Channel Bathymetry for Hydraulic Mod
This Science and Technology (S&T) Program research project would focus on Reclamation's need for hydraulic and physical habitat modeling to effectively address surface water operations for reliably delivering water and power while simultaneously ensuring compliance with environmental and Endangered Species Act (ESA) regulations. Accurate representation of three-dimensional (3D) channel topography is essential for hydraulic modeling and assessment of aquatic habitat.
NASA's EAARL is an emerging technology using a wavelength of laser light that is capable of mapping terrain both above and below the water surface. This technology efficiently maps large areas of channel networks with high resolution, precision, and accuracy. However, EAARL is currently configured for deep marine surveys. In streams with shallower water depths, LiDAR reflections become convolved. This research project investigates methods to separate surface and bed reflections in the full waveform EAARL data to improve the accuracy and representation of the channel topography for simulation applications.
Need and Benefit
Development of advanced surface water management tools is paramount to Reclamation's ability to reliably deliver water and generate power as effectively as possible. Reclamation's mission is to also understand the impacts of its project operations and resulting water quality implications to the surrounding ecosystem, particularly as it relates to threatened or endangered species.
Currently, existing commercial LiDAR and surveying methods (SHOALS) are insufficient in that they do not adequately produce representative topographic mapping of the river channel and terrain. The technology available is either capable of producing high resolution mapping of above water terrain or deep water bathymetry. However, commercial tools and technology are currently incapable of adequately representing both river channel and surrounding flood plain topography in a contiguous manner. The EAARL technology holds promise in being able to cost effectively and efficiently map large areas of river terrain in an effort to incorporate this information subsequently into management and decisionmaking type tools.
The EAARL technology uses an array of four high speed waveform digitizers connected to an array of four sub-nanosecond photo-detectors. The illuminated laser spot diameter on the surface is 20 centimeters. The SHOALS system uses a 2 meter diameter spot, one order of magnitude larger. EAARL's smaller surface diameter minimizes the reflecting water surface area as well as minimizes the broadening of the bed return pulses for a better bottom signal (indicating terrain). The other important feature of the EAARL technology is the Airborne LiDAR Processing System (ALPS) software. The ALPS is an open source programming tool that performs post-flight processing. Unlike SHOALS, this particular software has specialized algorithms, enabling it to produce bare Earth elevations necessary for developing modeling tools.
A specific test case for this LiDAR methodology is the Boise and Payette System, where approximately 146 river miles of EAARL data will have been collected. Populations of bull trout use Reclamation's reservoirs and the river systems within the Boise Project (which include the Boise River and Payette River basins). The U.S. Fish and Wildlife Service (USFWS) issued the Biological Opinion (BiOp) for Operations of Reclamation's Upper Snake River Projects in March 2005. The BiOp outlines monitoring requirements and associated Terms and Conditions that Reclamation must implement in order to ensure compliance with the ESA.
Reclamation will apply this methodology first on the Deadwood Reservoir Project, located on the Payette River system. River channel as well as water surface elevation surveying and habitat delineation will be performed in the field as part of this project to provide information necessary to improve the software algorithms for waveform delineation. The Boise River test case is specifically designed for simulations of water delivery and flood control operations within urban areas. Additionally, this information will be used to improve the EAARL instrumentation and data acquisition technology. Once this technique has been developed, it can be easily transferred to other basins for use. This proposal is also designed to expand upon previous work completed by Reclamation as part of an earlier S&T proposal identifying sources and magnitude of errors affiliated with commercial LiDAR technology compared to other traditional means.
Once the ALPS software has been improved and the topographic mapping completed for the riverine reach, a one-dimensional (1D) hydrodynamic model with a water quality module and aquatic habitat model will be developed for the purposes of testing the processed data as a means of evaluating the accuracy of the methodology under the various operational scenarios.
U.S. Geological Survey, Department of the Interior
Independent Peer Review
The following documents were reviewed by qualified Bureau of Reclamation employees. The findings were determined to be achieved using valid means.
Evaluation of LiDAR-Acquired Bathymetric and Topographic Data Accuracy in Various Hydrogeomorphic Settings in the Deadwood and South Fork Boise Rivers, West-Central Idaho, 2007Scientific (interim, PDF,
By Mr. Kenneth Skinner
Report completed on June 15, 2012
Evaluation of LiDAR-Acquired Bathymetric and Topographic Data Accuracy in Various Hydrogeomorphic Settings in the Lower Boise River, Southwestern Idaho, 2007Scientific (final, PDF,
By Mr. Kenneth Skinner
Report completed on June 15, 2012
Concurrently with the EAARL data co