Lidar and Geomorphic Change Detection: Useful Tools for River Ecosystem Assessment and Restoration Monitoring
Robert Dunn
Geosyntec Consultants
Atlanta, Georgia
Traditional stream survey methods have long been the preferred method for river ecosystem assessment and monitoring, however, topographic surveys, utilizing newer methods (UAVs, ground-based Lidar, survey-grade RTK GPS, etc.) are increasingly becoming more common in river ecosystem assessment and restoration monitoring. UAVs equipped with high-resolution Lidar scanners offer a suite of benefits for river restoration practitioners, including increased spatial coverage and data density, allowing practitioners to repeatedly collect topographic and geomorphic data beyond the traditional reach-scale, with less time than traditional methods. Further, the repeated acquisition of high-resolution topographic surveys over a river ecosystem allows assessment and/or monitoring of geomorphic change to be expanded spatially beyond reach-scale cross-sections and longitudinal profiles.
Employment of Geomorphic Change Detection (GCD) methods to repeat high-resolution topographic surveys of a river system allow practitioners to better understand the geomorphic rate and magnitude of change and how this relates to stream-system processes influencing form and function of a river system, especially in post-restoration scenarios. This presentation will highlight the use of UAVs to collect high resolution aerial data (LiDAR and photogrammetry) during pre- and post-peak flows along 15 river miles to evaluate ecosystem response and impacts. The repeat topographic surveys were used in the GCD software to generate spatially distributed maps of elevation, volume and areal change, which portray a detailed depiction of the magnitude and extents of change at both the reach scale and river scale. The presentation will include lessons learned, successes, and failures in the use of UAVs and aerial data for river ecosystem assessment and monitoring.
About Robert Dunn
Mr. Dunn is a water resource scientist and aquatic ecologist with Geosyntec Consultants out of Atlanta, Georgia. He graduated from Georgia College & State University with a Master’s and Bachelors in Biology and has nearly 6 years of natural resource and ecological consulting experience in streams, rivers, lakes, and coastal ecosystems. Mr. Dunn has applied principles of biology ecology, and natural resource management to a range of projects but his passion lies in ecosystem assessment and restoration, particularly fluvial ecosystems. Mr. Dunn has certifications in geomorphic assessment, characterization, and monitoring (Rosgen Levels 1, II, and III). His Experience in high resolution aerial data, including LiDAR and photogrammetry includes performing geomorphic change detection to assess the geomorphological impacts to streams resulting from proposed operational changes at water diversion facilities, utilizing aerial data to evaluate hydrotechnical hazards to develop design recommendations for pipeline and utility line crossings, and using aerial data for river assessment and monitoring.