Graduation Year

2009

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Geology

Major Professor

Mark Cable Rains, Ph.D.

Keywords

Hydrogeology, Groundwater, Temperature, Anadromous, Land use

Abstract

Temperature is an important physical characteristic of headwater streams that controls the presence and health of juvenile salmonids. Surface water temperature is controlled by many factors including exchanges with groundwater. A study of the hydrology of wetlands associated with headwater streams on the Lower Kenai Peninsula was conducted to determine the effect of geomorphic setting on groundwater discharge to streams and ultimately on in-stream water temperature. Attention was focused on drainage-way and discharge slope wetlands as two end-members of the geomorphic settings of the study area. Data were collected at 18 study reaches spanning four major watersheds in the study area. Surface water temperature and geochemical data were collected at all sites, while water levels were recorded at two heavily instrumented. Data showed discharge slopes had lower summer temperatures and more diffuse groundwater discharge than drainage-ways, though geochemical data showed the proportion of groundwater flowing through stream reaches was the same in both geomorphic settings. Thus, surface water temperature is influenced by groundwater discharge at the local scale, but not at the basin scale. Once groundwater emerges and becomes part of the surface water reservoir, it exchanges heat with the new environment and loses its temperature moderating properties, though it retains its geochemical signature.

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