Degree Year

2011

Document Type

Thesis

Degree Name

Bachelor of Arts

Department

Environmental Studies

Committee Member(s)

Scott Bailey, Chair
John Petersen
Bruce Simonson

Keywords

Hydropedology, Water sources, Stream chemistry

Abstract

Headwaters are the most ubiquitous stream type worldwide, provide invaluable ecosystem services, and regulate downstream chemistry. These systems have high sensitivity to disturbance, however, and thus are susceptible to change at low thresholds of environmental, climatic or human impact. In this study, we use fine scale sampling to describe spatial and temporal stream chemistry variations in a first order 0.41 km2 headwater catchment at Hubbard Brook Experimental Forest, NH, USA to pinpoint the landscape position and extent of dominant processes and controls on surface water. We discovered a range of stream water chemistry that is as variable as stream chemistry ranges seen at the scale of the entire Hubbard Brook Valley (35 km2). We examined surface and subsurface structure in an attempt to characterize controls on stream chemistry (e.g. upslope accumulated area, soil horizon development, type of parent material). Four potential sources and mechanisms controlling surface water characteristics were identified: discrete soil horizons, drainage from distinct soil type, riparian zone and near stream exchanges, and isolated seeps as distinct groundwater inputs. As water table depth and configuration strongly control soil development and chemistry of groundwater sources to the stream, changes in spatial patterns in stream chemistry may serve as an indicator of the impacts of a changing climate on key hydropedologic processes.

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