Date of Award

2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

P. J. Gerla

Abstract

During the last three decades, there has been much research on ground water/surface water interaction and hyporheic zone processes in natural rivers and streams. Research into natural systems has revealed significant ground water/surface water interaction and a complex variability that depends primarily on surface conditions, subsurface composition, and seasonal influences. Hyporheic zone interaction is an important factor contributing to water quality of both surface water and ground water systems.

This research expands on the concept of using heat transport, as revealed by temperature variation, as an analogue for water movement within a surface water/ground water system to include the man-made drainage ditch environment. The goal of this research is to use vertical temperature profiles as a means to identify locations along the drainage ditch where surface water/ground water exchange takes place within the hyporheic zone. To achieve this, an array of temperature data loggers was installed in a reach of Judicial Ditch #66 (JD66), within The Nature Conservancy's Glacial Ridge Project, a large-scale prairie/wetland restoration, approximately 24 km (15 miles) east of Crookston, Minnesota.

To characterize the hyporheic zone along the ditch, statistical analyses were conducted on the temperature data collected during the study. The two statistical tests used include a one-way analysis of variance (ANOVA) and a Tukey's test. The trajectory of ground water/surface water interaction, in-flow or out-flow of water from the channel, can be determined by comparing the results from a set of these statistical analyses. The resulting groups generated by Tukey's tests were reviewed for anomalous results. Locations that fall within an anomalous group suggest the occurrence of surface water-ground water exchange at that point along the ditch. By reviewing the characteristics of the anomaly, the direction of water exchange across the hyporheic zone can be inferred.

The methodology developed during this project may best be applied to processing large data sets generated from data logger instrumentation. The resulting analyses indicate the directionality of hyporheic exchange, if it is occurring at an instrumented location. Because of its ease and low cost, the methodology developed might best be used as a reconnaissance tool to identify areas along a ditch or stream reach for further instrumentation and research.

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