The impact of snowmelt on stream channel erosion and baselevel adjustments: McGee Creek, eastern California

Keywords: fluvial geomorphology, snowmelt, channel erosion, baselevel
Abstract Type: Poster Abstract

Abstract

Geomorphic processes in lower McGee Creek (eastern California) have been impacted by a century-long history of cattle grazing and loss of native riparian vegetation. Fed by discharge from Sierra Nevada snowmelt coupled with spring-fed groundwater, McGee Creek occupies a portion of the Long Valley Caldera and is characterized by a dominant single channel with a complex meander pattern. Using baseline data collected during drought conditions in spring 2022, this study focuses on monitoring stream channel erosion and changes in floodplain morphology following the significant snowfall of winter 2022/2023. An Unmanned Aerial System (UAS) was used to create a Digital Surface Model (DSM) verified by in-situ field measurements of snow depth and elevation points surveyed by real-time kinematic positioning (RTK) methods. Subsequent UAS flights through spring 2023 together with ground elevation surveys will be used to measure changes in snow depth and the magnitude of stream channel erosion. Prior studies have focused on the role of upstream contributions to discharge from meteoric sources and release of water for pastureland and inflow to neighboring Crowley Lake. This study is the first to assess the contribution of snow cover and spring melt to channel changes in McGee Creek.