Groundwater response to serial stream stage fluctuations in shallow unconfined alluvial aquifers along a regulated stream (West Virginia, USA)

Groundwater response to serial stream stage fluctuations in shallow unconfined alluvial aquifers along a regulated stream (West Virginia, USA) | Réponse des eaux souterraines à des fluctuations hydrologiques d’un cours d’eau au sein d’aquifères alluviaux libres peu profonds le long d’un cours d’eau régulé (Virginie occidentale, Etats-Unis d’Amérique). Respuesta del agua subterránea a una serie de escenarios de fluctuaciones de una corriente en acuíferos aluviales someros no confinados a lo largo de una corriente regulada (West Virginia, EEUU) (美国西佛吉尼亚州)沿管控河流区域浅层非承压冲积含水层地下水对连续河水位波动的响应 Resposta das águas subterrâneas a uma série de estágios de flutuação em aquíferos aluviais rasos não confinados ao longo um rio regulado (Virgínia Ocidental, EUA)

2016

Groundwater response to stream stage fluctuations was studied in two unconfined alluvial aquifers using a year-long time series of stream stages from two pools along a regulated stream in West Virginia, USA. The purpose was to analyze spatial and temporal variations in groundwater/surface-water interaction and to estimate induced infiltration rate and cumulative bank storage during an annual cycle of stream stage fluctuation. A convolution-integral method was used to simulate aquifer head at different distances from the stream caused by stream stage fluctuations and to estimate fluxes across the stream–aquifer boundary. Aquifer diffusivities were estimated by wiggle-matching time and amplitude of modeled response to multiple observed storm events. The peak lag time between observed stream and aquifer stage peaks ranged between 14 and 95 hour. Transient modeled diffusivity ranged from 1,000 to 7,500 m²/day and deviated from the measured and calculated single-peak stage-ratio diffusivity by 14–82 %. Stream stage fluctuation displayed more primary control over groundwater levels than recharge, especially during high-flow periods. Dam operations locally altered groundwater flow paths and velocity. The aquifer is more prone to surface-water control in the upper reaches of the pools where stream stage fluctuations are more pronounced than in the lower reaches. This method could be a useful tool for quick assessment of induced infiltration rate and bank storage related to contamination investigations or well-field management.

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