Date of Award:

12-2009

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Dr. Tamao Kasahara

Abstract

Mountain headwater catchments in the semi-arid Intermountain West are important sources of surface water because these high elevations receive more precipitation than neighboring lowlands. The hydrology of these mountain catchments is especially important as the region faces water shortages and conflicts. Conifer encroachment on aspen stands has been observed across the western US and can result in a decline in water yield. The overall objective of this study was to further our understanding of hillslope-stream connectivity in a headwater catchment of Northern Utah and any observable differences in this connection between aspen and conifer hillslopes. Hillslopes are the fundamental unit of a watershed. Therefore understanding processes at the hillslope scale is pertinent to managing valuable water resources. However, hillslope hydrology is understudied in the snow-driven, semi-arid west, leaving a gap in our knowledge of how watersheds function. This thesis focuses on how and when hillslope water contributes to stream water: hillslope-stream connectivity. Its specific objectives are (1) to compare peak snow accumulation under aspen and conifer stands, (2) to determine if shallow soil moisture shows organized patterns, indicating hillslope-connectivity and compare these patterns between vegetation types, (3) to examine hillslope-stream connectivity within deep layers of the soil profile and compare times of connectivity between vegetation types and (4) to find any thresholds past which hillslope-stream connectivity begins.

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