Riverscape and Geophysical Drivers
Physical and geologic covariates we hypothesized drove variation in flow
regimes were collected for each watershed (Table 1). We used the
National Hydrography Database Plus Version 2 data layer in ArcGIS Pro
(ESRI Redlands, CA) to obtain the slope of each stream segment, and the
area and mean slope for the watershed upstream of each site. We used the
USDA Web Soil Survey (NRCS 2023) for McCurtain County to calculate
geological metrics for each watershed, including mean depth to water
table and depth to impermeable layer, because groundwater inputs and
geologic permeability exert influences on streamflow (Costigan et al.
2015; Bourke et al. 2021). Additionally, we calculated the percentage of
each watershed that is forested, because vegetative type and cover
influence water movement, water use and evapotranspiration patterns
(Chappell and Tych 2012; Ellison et al. 2012). We imported a 2020 land
cover type dataset from the LandFire database (LANDFIRE 2020) into
ArcGIS Pro and determined the cumulative percentage of each watershed
that was covered by any category of forest.