This past August, three of us (Mark Fonstad, Aaron Zettler-Mann, and James Major) spent three days on the lower Sandy River between Mt. Hood and Portland. We were performing an experiment: how many river miles is it possible to float in a few days while at the same time flying a drone to collect very high resolution imagery from which channel sediment data and morphology can be extracted? We took the department’s cataraft, and while it is the ideal platform for this kind of work, the water levels in the Sandy River were low, and there was a fair amount of boat-dragging necessary. Nevertheless, we were able to cover about 40 km in those three days, and we collected 2-cm resolution imagery over almost every river bar along this section of the river. The Sandy River is geomorphically highly active, and is well known for the Marmot Dam removal higher in the watershed several years ago.
PhD Student Aaron Zettler-Mann has received a Doctoral Dissertation Improvement Grant from the National Science Foundation. Aaron’s dissertation is entitled “Lateral Channel Confinement and its Impact on Channel Morphology”, and this grant (for $15,912) will allow Aaron to conduct fieldwork and analysis of the Rogue River and the influence of lateral sediment supply on channel morphology. Aaron has extensive experience on extracting 3D data and orthophotographs from imagery, and these skills will allow him to produce sediment maps throughout the river system through automated feature extraction from imagery techniques. Aaron hopes to test the applicability of the sediment links theory concept to the Rogue River and extend the concept to sediment sources from hillslopes in addition to the traditional tributary sources. Aaron’s advisor is Mark Fonstad.
This summer Aaron Zettler-Mann conducted the first of two years of National Science Foundation funded dissertation work on the Rogue River in southern Oregon. Aaron is taking a riverscapes approach to examine how lateral channel constrictions such as roads, railroads, levees and bridge abutments impact channel morphology variables, including channel width, depth and the particle size distribution of river bars. This field work will also be used to further test the “Sediment Links” theory which suggests that patterns in channel width, depth and grain size are linked to the presence of tributaries. Field work for Aaron consisted of rafting over 60 kilometers, taking photographs from UAVs and a camera-on-a-pole of gravel bars, photographing the river banks and measuring channel depth. Below, pictures from the Rogue River. Clockwise from upper left: black bear sightings, UAV based image acquisition in the Recreation Section, battery charging and swimming at camp, camera-on-a-pole image acquisition in the Wild and Scenic section, on the water, and (center) gravel bar orthophoto ready for particle size distribution mapping.
In early June, doctoral candidate Aaron Zettler-Mann and recent baccalaureate graduate James Major spent three days flying a UAV on the Middle Fork of the John Day. The object of the project was to produce an orthophotograph of floodplain vegetation along a 2.5 kilometer by 0.5 kilometer section of the Middle Fork Valley Floor. The orthophoto will be used to map distinct vegetation species on the floodplain, with species identification occurring in the field. The resulting floodplain vegetation maps will be compared to previous field surveys of floodplain vegetation dating back as far as 1996. Additionally, this map will serve as baseline vegetation data going forward. Active channel restoration occurred beginning in July of 2017 and the vegetation map will allow future monitoring of floodplain vegetation communities which are a good indicator of changes to ground water flow. Below, the orthophoto compose for the study area and some pictures from the ground of vegetation and floodplain terrain.