Capturing tributary input dynamics in an oligotrophic lake using an autonomous surface vehicle

Tributary inputs alter physical and chemical lake characteristics through acting as a major source of external loading. These inputs vary temporally due to weather and seasonality, and spatially due to surrounding land use. The temporal and spatial constraints of traditional limnological point sampling methods make it difficult to capture fine-scale patterns in tributary input dynamics. However, advancements in autonomous surface vehicle (ASV) technology facilitate spatial mapping of plume boundaries in relation to tributary inflows, increasing our capacity to capture and evaluate patterns in tributary inputs. Using an ASV, Catabot, we captured tributary plume dynamics across summers 2021, 2022, and 2023 in the upper arms of oligotrophic Lake Sunapee (New Hampshire, USA). Surface surveys of water quality parameters collected during ASV deployments throughout each summer allowed us to quantify the distance and magnitude of tributary inputs, in relation to precipitation events and drought. We observed spatial gradients in specific conductance with higher concentrations located in proximity to tributary inflows; steeper gradients during mid-to-late summer co-occurred with periods of heightened precipitation. Specific conductance was highest in 2023, the wettest summer, and lowest in 2021, the dryest summer. Preliminary attempts to quantify the reach of tributary inputs, the distance to which the tributary plume extends into the lake, indicate that increased precipitation may have a larger influence on reach than prior drought occurrence.

Primary Presenter: Quin Shingai, Dartmouth College (quin.k.shingai.gr@dartmouth.edu)

Authors:

Quin Shingai, Dartmouth College  (quin.k.shingai.gr@dartmouth.edu)

Elizabeth Berendsen, Dartmouth College  (elizabeth.berendsen@gmail.com)

Tehya Kloster, Lake Sunapee Protective Association  (klostertr@gmail.com)

Emily Arsenault, College of Environmental Science and Forestry, State University of New York  (emarsena@esf.edu)

Jessica Trout-Haney, Dartmouth College  (jessica.volan.trout-haney@dartmouth.edu)

Mingi Jeong, Dartmouth College  (mingi.jeong.gr@dartmouth.edu)

Monika Roznere, Dartmouth College  (monika.roznere.gr@dartmouth.edu)

Kizito Masaba, Dartmouth College  (kizito.masaba.gr@dartmouth.edu)

Bethel Steele, Cary Institute of Ecosystem Studies  (steeleb@caryinstitue.org)

Alberto Quattrini Li, Dartmouth College  (alberto.quattrini.li@dartmouth.edu)

Kathryn Cottingham, Dartmouth College  (kathryn.l.cottingham@dartmouth.edu)