2.2 Hydrometric Field Measurements and Conservative Tracer
Injection
At all eleven sites, we monitored water level at 15-minute intervals
from May 01, 2018 through September 30, 2018 using either TruTrack
Capacitance Rods or HOBO U20L Pressure Transducers. To capture relative
stage dynamics, we standardized mean daily stage as a z-score by
normalizing mean daily stage by the seasonal (i.e., May-September) mean
and standard deviation of water levels across the period of record at
each individual site. Precipitation (2018 water year total: 645 mm) and
snow water equivalent (2018 peak: 401 mm) records were obtained from the
Wild Basin SNOTEL, #1042, (2914 m), located within the watershed.
To determine how river-floodplain connectivity changed as a function of
streamflow we conducted instantaneous NaCl injection experiments at high
(June 13, 2018) and low flows (July 30, 2018). We injected NaCl into the
main stem of the river, 125m upstream from Inflow, and monitored the
change in specific conductance (SC) over time (i.e., the breakthrough
curve, BTC) at six downstream locations (Table 1) using Campbell
CS547A-L conductivity loggers. We calculated modal velocity
(Vm) as the time to peak (TTP) divided by the flow path
distance from the injection site (DISTf) to the
monitoring site.