An Overview
Program: RESESS Boulder
Major: Rockology (Geology)
Academic Affiliation: Louisiana State University
Biography
Rorisang Kgoadi is currently exploring and studying rockology (geology) as an undergraduate at Louisiana State University. He is particularly interested in rift dynamics and plans to look at this subject in graduate school. Among other interests, Rori loves to bake, cook, read, and go out into nature. During the 2023 RESESS program, he will be working on looking at how metals interact with groundwater and surface water in an alpine stream.
Abstract
Groundwater-surface water (GW-SW) interactions have key implications for biogeochemical cycling as well as stream restoration and remediation. They are controlled by a complex web of temporally-variable processes related to geology, geomorphology, and biogeochemistry. Understanding how GW-SW connections function in space and time is important for evaluating current and long-term water quality along with creating and implementing water remediation strategies, whether natural or artificial. Here, we examine a metal-impacted reach of the Coal Creek watershed in Crested Butte, Colorado to determine where GW-SW interactions are present and the possible sources that introduce stream geochemical changes. To do so, we collect stream and groundwater chemistry, pH, temperature, and fluid electrical conductivity data through synoptic sampling and conducted salt tracer injections coupled with bulk electrical resistivity data to map and explore stream GW-SW interactions. These data are compared against the previous year’s data to determine how geochemical conditions evolve over time in the hyporheic zone, the interface between groundwater and surface water where many chemical reactions occur. We expect the reach we study to have little to no connection to the hyporheic zone given the presence of clays, which would indicate that there are minimal GW-SW interactions, limiting the stream’s ability to self-remediate. Our data show some groundwater contributions, likely associated with fractures, and are a part of the long-term transition from a snowmelt-dominated to a groundwater-dominated stream. Determining where GW-SW interactions are present and how they evolve through the year helps determine the type of physical and chemical dynamics Coal Creek displays in this specific reach, and its ability to process metals