Date of Completion
Martin A. Briggs, Amvrossios Bagtzoglou, Jason Vokoun
Field of Study
Master of Engineering
Rising summer stream temperatures threaten the habitat of cold-water fishes globally. Streams with cold groundwater seeps can provide thermal refuge, however natural groundwater discharge is often patchy throughout watersheds, impacting habitat connectivity. This research was undertaken to evaluate the potential to engineer (active pumping) thermal refuge that mimic cold groundwater seeps under a range of natural streamflow conditions and varying cold-water injection rates. Natural groundwater averaging 10 °C was pumped into the river channel behind a removable baffle, used to inhibit mixing and dispersal of the groundwater plume. A fiber-optic distributed temperature sensing cable was deployed above the streambed, downstream of the injection point. Visible light and thermal infrared images were collected of the water surface. The goal of this research was to collect data at high, medium, and low natural stream discharges in the Fenton River near the University of Connecticut in Storrs, CT, USA, as well as test high, medium, and low injection rates relative to typical monitoring well pump rates. The range of cold anomalies monitored by the FO-DTS cable indicated a -0.09 °C temperature drop between the surface water and minimum temperature in the cold-water plume at high flow stream discharge, -0.31°C temperature change for medium discharge, and a -1.1°C temperature decrease for low stream flow discharge. The three varied rate pumping tests indicated that an increase in pumping rate creates a slightly cooler plume, but does not make a substantially large difference at an overall stream discharge rate of 0.42 m3/s at the Fenton River.
Thielman, Rebekah, "Evaluation of Engineered Thermal Refuge in Streams as a Climate Warming Mitigation Strategy for Fish Populations Experiencing Thermal Stress" (2020). Master's Theses. 1531.