Soil water program
Soil water from three soil profiles (called the S-transect) located 4, 12 and 22 m from the C2 stream have been monitored 5-12 times per year since 1995 for water isotopes and water chemistry (Nyberg et al. 2001; Bishop et al., 2004; Lidman et al. 2017, Blackburn et al. 2017). The S-transect is aligned based on topography, following the lateral flowpath of groundwater. Each profile consists of measurements at six soil depths between 5 and 90 cm using ceramic suction lysimeters (P100). Soil water content using Time-domain reflectometry (TDR) and soil temperatures are measured at the same depths. A similar setup was installed in one of the wetland soils upstream of C4 to monitor soil water chemistry since 1997 using 12 nested wells extending to different depths, ranging from 25 to 350 cm below the ground surface (Lidman et al. 2013; Sponseller et al. 2018). ). In 2007, the Riparian Observatory of Krycklan, a complementary set of transects to represent a range of topographic situations was also established (Grabs et al., 2012).
Ten pairs of DRIP (Discrete Riparian Inflow Point) and non-DRIP well transects were established in 2015 in riparian zones in central KCS streams (Fig. 1d). Each pair is located adjacent to each other and therefore experience comparable environmental conditions, except for in the groundwater hydrology. DRIP sites are located on the receiving end of converging groundwater flow paths, and are characterized by shallow water tables, often reaching the soil surface before converging with streams (see Leach et al. 2017). Non-DRIP sites are situated in more elevated, drier riparian areas. Each transect is equipped with three fully screened groundwater wells, situated in riparian (0-3 m distance from the stream), transition (10 m distance from the stream), and upland (20 m distance from the stream) areas (Ploum et al. 2020).