An Overview
Major: Environmental Science
Academic Affiliation: Haskell Indian Nations University
Biography
Ian Gambill will be a senior in the B.S. of Environmental Science at Haskell Indian Nations University in Lawrence, KS. His past research includes a project where Ian compared two wetland systems using dissolved oxygen as a water quality indicator. In the summer of 2019, Ian participated in the RESESS program where he helped to characterize hyporheic activity in a complex region of a stream system in northern Colorado. He hopes to work on water resource sustainability/remediation and leave a positive impact. Ian also enjoys music, art, film, and literature.
Abstract
Characterizing Hyporheic Extent with Electrical Resistivity and Concentration Breakthrough Curves
Stream-water systems provide complexity and diversity to ecosystems. Large wood (LW) and logjam-dense reaches of a stream have been shown to increase stream complexity, therefore, increasing the potential for biodiversity. The flow of water through a slower-moving segment of a stream increases the potential for nutrient exchange and pollutant transformation. Many of these processes occur in the hyporheic zone, an area of saturated porous media around a stream that provides an interface in which stream-water and groundwater interact. Quantifying the behavior in hyporheic exchange may help us further understand the geochemical and geophysical processes that improve the biodiversity and water quality of an ecosystem. The goal of this research is to further understand and characterize activity in the hyporheic zone. Traditionally, methods to quantify hyporheic activity were cumbersome and insufficient. We utilized geophysical methods including electrical resistivity (ER), to observe subsurface flow, and in-stream electrical conductivity (EC) to monitor a tracer test. We then created breakthrough curves (BTC’s) which were compared and used as a proxy for hyporheic and instream transport behavior in two complex reaches of a stream. Within the ER BTC, asymmetry describes the skewness and the tailing behavior indicates solute retention, therefore, indicating hyporheic activity. The ER BTC displayed stronger tailing behavior than instream measurements which indicate that hyporheic behavior is related to slower movement and longer residence times during solute transport. This study supplies data that demonstrates that ER methods coupled with tracer tests effectively characterize hyporheic activity in complex reaches of a stream.