Intrastream variability in solute transport: Hydrologic and geomorphic controls on solute retention

摘要: [1] Hydrologic fluctuations and geomorphic heterogeneity are expected to produce substantial variability in solute transport within rivers. However, this has not been sufficiently explored due the limited availability of injection data most Here, we analyzed 81 tracer breakthrough curves (BTCs) along Stringer Creek, a 5.5 km2 watershed Montana. BTC measurements were obtained for three baseflow conditions at 27 reaches 2600 m stream channel. BTCs upstream (first 1400 m) had receding tails with shallow slopes, indicating high retention. Conversely, downstream (1400 2600 m) steeper low retention relative reaches. Difference channel coincided changes morphology bedrock geology. Specifically, slope increases from 5–6% (upstream) 9% (downstream), sinuosity decreases maximum 1.32 1.02 underlying sandstone granite-gneiss (downstream). Importantly, intrastream differences distinctly observable only during two lowest conditions. Spatial tail-slopes was sensitive local discharge flow, flow. varied temporally velocity reaches, but These results suggest that interactions between vary hydrologic conditions, becomes more homogeneous higher discharge.