Speaker: Raddiete Ghion

Topic: Understanding the nature of stream-aquifer interaction  

Abstract

Understanding the nature of stream-aquifer interaction is important for understanding the degree of hydraulic connection between streams and adjacent aquifers within any given watershed. Such information is necessary before the effects of groundwater pumping on streamflow, or the effects of surface-water runoff on aquifer recharge, can be assessed. Traditional techniques to analyze stream-aquifer interaction are based on digital groundwater flow models; however, aquifer parameters for model calibrations are generally unavailable or difficult and costly to obtain. Recession curve analysis is an alternative approach to determining stream-aquifer interaction.

This study sought to investigate changes in precipitation, streamflow, baseflow, and hydrologic properties of the Pedernales watershed in central Texas, as well as identify the primary aquifer contributing flow to the Pedernales River between 1940 and 2014. The USGS Ground Water Tool Box RECESS program was used to extract meaningful segments of streamflow recession and the slope (K) of such segments (recession curve index, RCI). Man-Kendall Monotonic trend (MK) tests were used to assess changes in climatologic and hydrologic conditions during the study period. The results of annual trend analysis of precipitation, streamflow, baseflow and RCI showed no significant changes over the study period. Results of this study are relevant to water resource management in the study area to satisfy the needs of a growing population while maintaining the ecological integrity of the stream-aquifer system. The approach used in this study is transferable to other watersheds as method requires only streamflow hydrograph and recession analysis.

Bio

Raddiete Ghion is the Geoscience Outreach Coordinator at the Kimbell School of Geoscience. She is the BEST program grant coordinator. The BEST program is an NSF grant funded initiative intended to increase the number of undergraduates at MSU pursuing a geoscience major through authentic, career-relevant experiences. Raddiete earned her B.S. in Biology and an M.S. in Aquatic Resources from Texas State University. During her graduate studies Raddiete investigated groundwater surface water interactions in the Pedernales Watershed for her thesis research. While in graduate school Raddiete interned for the Meadows Center for Water and the Environment, where she gained hydrological field work experience. Raddiete was also a water quality monitor with the Texas Stream Team. Raddiete will present her graduate thesis research, where she will discuss stream aquifer interactions in the Pedernales Watershed.