Date of Award:

5-2011

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Advisor/Chair:

Bethany T. Neilson

Abstract

The purpose of this study is to investigate variation in water export and instream temperatures throughout the open water season in a beaded Arctic stream, consisting of small pools connected by shallow chutes. The goals are to better understand heat and mass movement through these systems, how this may impact chemical and biological processes, and the resulting shifts with changes in climate. This is accomplished by first examining the extent and variability of water storage and export through qualitative analysis of observational data. Further, heat fate and transport is examined through development of an instream temperature model. The model formulation, a simple approach to model calibration and validation, and information regarding residence and characteristic times of different pool layers are presented. Using temperatures measured at high spatial resolution within the pools and surrounding bed sediments as well as other supporting data (e.g., instream flow, specific conductivity, weather data, and bathymetry), various types of storage within the pools, banks, and marshy areas within the riparian zone, including subsurface flow paths that connect the pools, were found. Additionally, data illustrated that some pools will stay stratified during higher flow periods under certain weather conditions. Through modeling efforts, the dominant heat sources were found to vary between stratified layers. It was also found that potential increases in thaw depths surrounding these pools can shift stratification and mixing patterns. These shifts can further influence mass export dynamics and instream water quality. Given the amount and different types of storage within these systems and the influence of stratification patterns on the residence times in the pools, Imnavait Basin and similar beaded Arctic watersheds will likely experience delayed export of nutrients that are limiting in most Arctic systems.

Comments

This work made publicly available electronically on May 11, 2011.

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