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Characterization of Pre and Post Re-Naturalized Surface Water/Groundwater Exchange, Jocko River, Flathead Indian Reservation, Montana

by Pete, Shandin Hashkeh

Abstract (Summary)
ABSTRACT Pete, Shandin, Hashkeh, M.S., December, 2006 Geology Characterization of Pre and Post Re-Naturalized Surface Water/Groundwater Exchange, Jocko River, Flathead Indian Reservation, Montana. Chair: Dr. William Woessner Construction of flood protection levees in the 1950s resulted in channel incision of 2200 ft of the Jocko River. Resulting floodplain water table lowering is thought to have altered surface water/groundwater interactions, impairing riparian habitat and trout fisheries. The objective of this research was to establish the hydraulic link between the stream and floodplain under pre-restored/re-naturalize conditions; assist the Confederated Salish and Kootenai Tribes in design and implementation efforts to re-naturalize the Jocko River. The Jocko River was instrumented with 11 staff gauges to establish river stage. Monthly water level monitoring of ~50 shallow monitoring and domestic wells along with continuous water level recorders were used to establish the pre- and postrestoration water table position. Grain size analyses, falling head slug tests, seepage runs, mini-piezometers and streambed temperature profiles were used to define the direction and magnitudes of channel-groundwater exchange. Study results show the upper 6400 ft of the river in the study area is primarily a losing reach, whereas the lower portion is a gaining reach throughout the year. Seasonally, the transition point between gaining and losing sections migrates (~3000 ft) upstream. The floodplain aquifer hydraulic conductivities range from 7 to 280 ft/day whereas, riverbed vertical hydraulic conductivities range from 0.1 to 187 ft/day. Initial channel restoration increased the riverbed elevation (~ 3 ft). A correlation exist between river discharge and water table elevation changes near the river whereas, water table elevations further from the river are not correlated. Floodplain water table elevations increased (~0.5 to 1.8 ft) near the restored reach. Streambed vertical hydraulic conductivity and grain size distributions showed minimal changes. Vertical hydraulic gradients in the restored reach showed significant deviations (~0.4) from the pre-restoration established values and patterns. In June 2005, a runoff event exceeded a 20-year flood recurrence interval that may have reduced the ability to measure changes in surface water/groundwater exchange. The transient nature of this river and groundwater system calls setting clear quantitative restoration goals and objectives. Continued long term monitoring will allow for accurate assessment of the overall success of this restoration effort.
Bibliographical Information:

Advisor:Dr. William W. Woessner; Dr. Scott Woods; Dr. Johnnie Moore

School:The University of Montana

School Location:USA - Montana

Source Type:Master's Thesis

Keywords:geoscience

ISBN:

Date of Publication:03/02/2007

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