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In this study, the dissolved oxygen (DO) alteration method (Chlebica and Robbins 2013) is used to evaluate the patterns of flow into and vertically within shallow screened monitoring wells. The method entails bubbling air into a well, followed by conducting DO profiles with time. Tests were conducted in six standard 2" (5 cm) polyvinyl chloride shallow screened monitoring wells at four test sites in Storrs, Connecticut. Test sites vary in formation permeability, flow patterns, and nearby geographic features influencing flow. The method provides a means for groundwater flow characterization and potentially improved interpretation of contamination sampling results in the absence of detailed three‐dimensional hydrogeologic information.

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Determination of vertical flow rates in a fractured bedrock well can aid in planning and implementing hydraulic tests, water quality sampling, and improving interpretations of water quality data. Although flowmeters are highly accurate in flow rate measurement, the high cost and logistics may be limiting. In this study the dissolved oxygen alteration method (DOAM) is expanded upon as a low-cost alternative to determine vertical flow rates in crystalline bedrock wells. The method entails altering the dissolved oxygen content in the wellbore through bubbler aeration, and monitoring the vertical advective movement of the dissolved oxygen over time. Measurements were taken for upward and downward flows, and under ambient and pumping conditions. Vertical flow rates from 0.06 to 2.30 Lpm were measured. To validate the method, flow rates determined with the DOAM were compared to pump discharge rates and found to be in agreement within 2.5%.

Many rural communities depend on bedrock wells as a primary water source, which raises the issue as to whether increasing amounts of salt application are affecting bedrock water quality and to what degree. Through wellbore profiling, this study investigated changes in specific conductance in two crystalline bedrock wells at the University of Connecticut in Storrs, CT, from 2003 to 2016, with particular emphasis on the impacts of increased salt application with a change in deicing practices at the university after 2009. Hourly specific conductance measurements were collected in 2014 to determine how water source may affect wellbore concentrations seasonally. Chloride was found to be highly persistent in the bedrock, with concentrations consistently increasing from 2003 to 2016 despite year-to-year variations in salt application. A dramatic increase in chloride occurred in the wellbores in response to the change in deicing practices, with an immediate response in fractures having a direct connection to the overburden. In light of the long-term implications of road salting on subsurface chloride contamination, this study argues that consideration be given to deicing management strategies to reduce road salt contamination.

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Water resources management is one of the most important challenges worldwide because water represents a vital resource for sustaining life and environment. In the aim of sustainable groundwater management, the identification of aquifer recharge areas is a useful tool for water resources protection. In a well-developed karst aquifer, environmental isotopes provide support for identifying aquifer recharge areas, residence time and interconnections between aquifer systems. This study deals the use of environmental isotopes to identify the main recharge area of a karst aquifer in the Upper Valley of Aniene River (Central Italy). The analysis of 18O/16O and 2H/H values and their spatial distribution in the aquifer, make it possible to trace back groundwater recharge areas based on average isotope elevations. The Inverse Hydrogeological Balance Method was used to validate spring recharge elevations obtained by the use of stable isotopes. Areas impacted by direct and rapid rainfall recharge into the study area were delineated, showing groundwater flowpaths from the boundaries to the core of the aquifer. The results of this study demonstrate the contribution that spatial and temporal isotope changes can provide to the identification of groundwater flowpaths in a karst basin, taking into account the hydrogeological setting

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