Julianne Davis (Syracuse University) will present:
“Assessing the Impacts of Beaver Dam Analogues on Channel Morphology in Western Rangelands.”
The loss of beaver in the western US due to trapping and land use changes has reduced former beaver meadows and wetlands to single thread, incised stream channels. In response to this degradation, landowners have begun to implement beaver-inspired stream restoration projects, such as constructed beaver dam analogues (BDAs). BDAs are intended to re-store incised streams by increasing sediment deposition in the channel, promoting ponding and groundwater storage, and improving riparian vegetation health. In spite of a recent surge in enthusiasm for BDAs, research on the impacts of these structures is lacking.
A team from Syracuse University, SUNY ESF and The Nature Conservancy of Wyoming (TNC) is examining the effects of BDA restoration projects in Red Canyon Creek in south-central Wyoming. Five BDAs were installed along a ~500 m reach of Red Canyon Creek in 2018 with the goals of reducing channel erosion and increasing surface water and groundwater storage. This talk will focus on the first restoration goal, discussing the changes in channel morphology that occurred after one year of BDA presence in the creek. Changes in erosion and deposition due to BDA installation were quantified by comparing the 2018 and 2019 digital elevation models (DEMs) generated from visible light images collected during annual unoccupied aerial vehicle (UAV) surveys. An upstream reach without BDAs was also studied to isolate the morphologic changes resulting from BDA installation from natural channel variability. The BDAs promoted extensive changes in channel morphology from 2018 - 2019, with the BDA reach experiencing more deposition and more erosion than the reference reach. These results, as well as the increasing number of BDAs installed in the western US, highlight the importance of continuing to investigate the effects of BDAs and assessing whether BDAs achieve stream restoration goals.
Becky Nesel (SUNY Oswego) will present:
“Grainsize Analysis of Searles Lake, CA”
Extreme drought in southern California has the potential to impact ecosystems and millions of people, but the climate mechanisms that control regional water availability are poorly understood. It is important to understand the causes of ex-treme droughts so they can be better predicted in the future. This is challenging because of complicated physical relation-ships within the climate system and because of a combination of natural and anthropogenic causes. One way to determine past climate events is through the use of lake sediment cores. The sediment that accumulates in lakes is sensitive to water availability. Grainsize analysis can indicate changes in lake levels because mud deposition is often a result of deep water and silts and sands indicate shallower water or dried up lake floor where sediment can be blown across the lake bed or transported by small ephemeral streams. Together, these processes provide a physical link between sediment grainsize and past lake water balances.
One such lake that contains an amazing history is Searles Lake, located in southern California. The lake sediments contain alternating mud and evaporite layers which correspond to wetter and dryer conditions at Searles Lake over the last ~150,000 years. Today, the lake is mostly evaporited. Here, we examine the grainsizes of samples from mud and evaporite layers from drill cuttings between the interval of 258 feet to 440 feet to examine the correspondence of grainsize and physi-cal stratigraphy. Our initial grainsize analysis of mostly evaporites, interpreted as dryer climate, show higher percentages of larger grainsizes compared to the mud samples, mostly muds which correspond with deeper lake conditions. The grainsize analysis from Searles Lake provides an initial framework for further study of the cycles of drought in the desert southwest.
Micah Weisner (Syracuse University) will present:
“'Paleothermometer Calibration in Fayetteville Green Lake”