Quantifying vegetation transpirational controls on streamflow in the Lehman Creek watershed to estimate potential effects of anthropogenic climate change
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Authors
Hedge, Christine
Issue Date
2014
Type
Thesis
Language
Keywords
Climate change , Evapotranspiration , Great Basin , Lehman Creek watershed , Streamflow , Transpiration
Alternative Title
Abstract
While a number of studies have documented the occurrence of climate change in the Western U.S., no studies have used modern instrumental climate data to quantify the potential effect of climate change-induced increases in transpiration on streamflow (Q) in the Great Basin. We hypothesized that an increase in plant transpiration in the Lehman Creek watershed in Great Basin National Park, as a result of anthropogenic climate warming, may result in a measurable reduction in Q. We sought to quantify: (1) evapotranspiration (ET) controls on Q in the Lehman Creek watershed and how variations in ET would affect Q, and (2) how projected climate changes would impact transpiration and thus Q. Using data from the Parameter-Elevation Regressions on Independent Slopes Model, USGS, and nearby SNOTEL and weather stations, we calculated seasonal and annual ET using a general watershed balance equation. Linear regression analysis of time series data were used to evaluate short and long term patterns in climate, and to quantify relationships among precipitation, ET, Q, and air temperature. We also calculated the effects of simulated climate-induced increases in ET of 10-50% on Q. Snow water equivalent was the strongest determinant of annual ET and Q on an annual scale; however, early season air temperature was also a strong modulator of ET and Q. Years of warmer, faster, and earlier starts to early season air temperature resulted in earlier and higher early season ET, and thus lower Q. Small to moderate increases in simulated ET of 10-20% resulted in significant reductions (mean 5-10%) in Q with a 1.5-3 week extension of the growing season for drier years. Results demonstrate the risks to surface water flows in watersheds of the Great Basin and western U.S. that may result from earlier starts to the growing season, longer growing seasons, or growing seasons with higher amounts of transpiration that may result if the climate of the Great Basin continues to warm.
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In Copyright(All Rights Reserved)