Riparian hydraulic gradient and stream‐groundwater exchange dynamics in steep headwater valleys

摘要: [1] Patterns of riparian hydraulic gradients and stream-groundwater exchange in headwater catchments provide the hydrologic context for important ecological processes. Although controls are relatively well understood, their dynamics during periods change is not. We investigate over three different time scales two steep, forested, Oregon (WS01 WS03) to determine potential reach-scale valley slope cross-sectional geometry. Groundwater stream stage data collected at high spatial temporal resolutions a period encompassing 1.25 year storm subsequent seasonal baseflow recession indicate that both aquifers exhibit strong persistence down-valley dominance. Responses rainfall do not support simple conceptual models increased gradient toward streams. Hydraulic response WS01 suggested exchange, but there was less evidence this WS03. Results from four constant-rate tracer injections each showed baseline level overall, slight increase (WS01) decrease (WS03) intrusion tracer-labeled water as discharge receded. These results steep floors host extensive very little table 3 orders magnitude discharge.