Far-Field Interactions Between a River and an Aquifer Due to Regulated and Natural Floods

This project seeks to analyze and interpret how hydropeaking along the Lower Colorado River (LCR) at Hornsby Bend, TX, will impact physical and chemical properties of a nearby aquifer. The LCR has been the focus of several studies investigating how hydropeaking and natural floods affect and promote connectivity and exchange among the LCR, the hyporheic zone, and riparian zone aquifer. However, these studies have mostly concentrated on processes occurring in the bed and the first few meters (~ 5 m ) of the bank. We expand on these studies. The heavy rains received throughout central Texas during hurricane season causes more frequent, prolonged dam releases, and flooding that result in a dramatic rise in the LCR, with floods reaching heights of more than 5 m at times. These floods and rain result in an influx of water into the aquifer, but the biochemical alterations and residence times of this water is unknown. Multiple piezometers ranging between 10 and 50 m from the bank of the LCR will be monitored over the course of several months using pressure, temperature and conductivity transducers. Some groundwater and river water samples will be collected simultaneously. The resulting data will be used to understand how the water table changes with flood events and how long the influx water stays in the outer regions of the river banks.