Investigation of Groundwater Flow Variations near a Recharge Pond with Repeat Deliberate Tracer Experiments

Abstract

Abstract:Determining hydraulic connections and travel times between recharge facilities and production wells has become increasingly important for permitting and operating managed aquifer recharge (MAR) sites, a water supply strategy that transfers surface water into aquifers for storage and later extraction. This knowledge is critical for examining water quality changes and assessing the potential for future contamination. Deliberate tracer experiments are the best method for determining travel times and identifying preferential flow paths between recharge sites over the time scales of weeks to a few years. This paper compares the results of two deliberate tracer experiments at Kraemer Basin, Orange County, CA, USA. Results from the first experiment, which was conducted in October 1998, showed that a region of highly transmissive sedimentary material extends down gradient from the basin for more than 3 km [1]. Mean groundwater velocities were determined to be approximately 2 km/year in this region based on the arrival time of the tracer center of mass. A second experiment was initiated in January 2008 to determine if travel times from this basin to monitoring and production wells changed during the past decade in response to new recharge conditions. Results indicate that flow near Kraemer Basin was stable, and travel times to most wells determined during both experiments agree within the experimental uncertainty.

Tracer test modeling for characterizing heterogeneity and local-scale residence time distribution in an artificial recharge site

“…Understanding hydraulics entails an understanding of the spatial and temporal distributions of water fluxes around the recharge system and the relationship between the recharge system and the aquifer (i.e., recharge affected area, mixing of recharged and native groundwater, travel times; Clark et al, 2004Clark et al, , 2014Massmann et al, 2008;Bekele et al, 2014). The flux distribution is affected by the complexity and heterogeneity of natural systems.…”

Quantifying Apparent Groundwater Ages near Managed Aquifer Recharge Operations Using Radio-Sulfur (35S) as an Intrinsic Tracer

“…Earlier deliberate tracer experiments demonstrated that a zone of highly transmissive material extends down gradient of Kraemer Basin for more than 3 km [9,37]. Within this zone, linear groundwater velocities are approximately 2000 m/year.…”

“…Groundwater samples (Table 3) were collected from seven monitoring wells (AM-7/1, AM-8/1, AM-48/1, AM-12/1, AM-12/2, and KBS-3/1) and one production well (PW1), all of which were shown to be hydraulically connected with Kraemer Basin using earlier deliberate tracer experiments [9,37]. AM-12/1 and AM-12/2 are at the same location but screened at different depths with AM-12/2 at the deeper interval.…”

Environmental Tracers

“…Three further USA case studies [17][18][19] deploy applied tracers alongside ambient tracers. Cowie et al [17] use a two-tier investigative approach in a flooded, abandoned, underground hard-rock mine system (USA).…”

“…Finally, Clark et al [19] have applied (injected) the environmental gas tracers SF6 and Xe in groundwater to characterise hydraulic connections between recharge facilities and production wells of a Managed Aquifer Recharge (MAR) site. MAR involves a strategy of injecting "surface waters into aquifers for storage and later extraction".…”