Hydrologic Turnover Matters — Gross Gains and Losses of Six First‐Order Streams Across Contrasting Landscapes and Flow Regimes

Abstract

The exchange of stream water with groundwater, and vice versa, is an important driver of stream ecosystem functioning, such as ecosystem metabolism and solute processing (e.g.,

Catchment Properties Shape Seasonal Variation in Groundwater‐Surface Water Interaction—Geogenic Silica as a Proxy for Hydrological Turnover Induced Mixing

“…Since 500 m reaches are larger than comparable setups in the literature (Jähkel et al., 2022; Jimenez‐Fernadez et al., 2021; Payn et al., 2009), we divided the study sites into two equidistant sub‐reaches, resulting in three individual differential discharge gauging experiments. This enabled us to calculate HT parameters for the sub‐reaches A and B and the total reach C separately.…”

“…In the works of Covino et al (2011) and Mallard et al (2014), HT measurements took place between May and September. In other studies, HT measurements were carried out in one catchment during summer baseflow recession (Payn et al, 2009), in four sets under baseflow conditions (Ward et al, 2013), in two short campaigns at baseflow conditions in summer and winter (Jimenez-Fernandez et al, 2021), or in seven campaigns at different streams over one hydrological year (Jähkel et al, 2022). We present a data set where all these periods are covered by measurements during two hydrological years.…”

“…Hence, these processes need to be better understood, supporting the development of improved HT modeling approaches on the catchment scale. Only limited numbers of HT observations have been published in the international literature so far (e.g., Covino et al., 2011; Jähkel et al., 2022; Jimenez‐Fernadez et al., 2021; Mallard et al., 2014; Payn et al., 2009). Most of these studies were either limited in scale with consistent reach segments of about 100 m (Jähkel et al., 2022; Jimenez‐Fernadez et al., 2021) covering two seasons, or observation periods capture 4 months in the same season, respectively (Covino et al., 2011; Mallard et al., 2014; Payn et al., 2009).…”

“…However, the combination of silica with salt dilution gauging based HT measurements opens a different perspective onto HT processes. The tracer injection based measurement approach is up till now, the only available method of quantifying gross gains and losses resulting in HT estimation of larger stream segments (Covino et al., 2011; Jähkel et al., 2022; Jimenez‐Fernadez et al., 2021; Mallard et al., 2014; Payn et al., 2009).…”

Catchment properties shape seasonal variation in groundwater- surface water interaction - geogenic silicate as a proxy for hydrological turnover induced mixing

“…Altogether, these processes induce the spatial and temporal variability of HT processes. However, reach specific features on, i.e hillslope topography, geology, vegetation, and valley bottom structure influence streamflow dynamics and GW-SW interaction (Bergstrom et al, 2016;Jähkel et al, 2022;Jimenez-Fernadez et al, 2021) and studies measuring HT at the reach and catchment scale show that discharge can explain the variance in HT quite well (Covino et al, 2011;Mallard et al, 2014).…”