TY - JOUR
T1 - Unravelling groundwater contributions to evapotranspiration and constraining water fluxes in a high-elevation catchment
AU - Ryken, Anna C.
AU - Gochis, David
AU - Maxwell, Reed M.
N1 - Funding Information:
We gratefully acknowledge Billy Barr (Rocky Mountain Biological Laboratory) for the Billy Barr Station precipitation data as well as Peter Blanken and Sean Burns, and Marcy Litvak for the Niwot Ridge and Valles Caldera evapotranspiration data, respectively. Funding for the AmeriFlux core site US‐NR1 data was provided by the U.S. Department of Energy's Office of Science. We gratefully acknowledge Tetsu Tokunaga for the soil moisture data from the well located near the flux tower in the East River Catchment. This work was supported by the U.S. Department of Energy Office of Science, Biological and Environmental Research (BER) grant number DE‐SC0016491.
Funding Information:
We gratefully acknowledge Billy Barr (Rocky Mountain Biological Laboratory) for the Billy Barr Station precipitation data as well as Peter Blanken and Sean Burns, and Marcy Litvak for the Niwot Ridge and Valles Caldera evapotranspiration data, respectively. Funding for the?AmeriFlux core site US-NR1 data was provided by the U.S. Department of Energy's Office of Science. We gratefully acknowledge Tetsu Tokunaga for the soil moisture data from the well located near the flux tower in the East River Catchment. This work was supported by the U.S. Department of Energy Office of Science, Biological and Environmental Research (BER) grant number DE-SC0016491.
Publisher Copyright:
© 2021 John Wiley & Sons Ltd.
PY - 2022/1
Y1 - 2022/1
N2 - Despite the importance of headwater catchments for the water supply of the western United States, these regions are often poorly understood, particularly with respect to quantitative understanding of evapotranspiration (ET) fluxes. Heterogeneity of land cover, physiography, and atmospheric patterns in these high-elevation regions lead to difficulty in developing spatially-distributed characterization of ET. As the largest terrestrial water flux behind precipitation, ET represents a significant fraction of the water budget for any watershed. Likewise, groundwater is the largest available freshwater store and has been shown to play a large role in the water balance, even in headwater systems. Using an eddy covariance tower in the East River Catchment, a Colorado River headwaters basin, we estimated water and energy fluxes in high-elevation, complex systems to better constrain ET estimates and calculate overall water and energy budgets, including losses from groundwater. We used the eddy covariance method to estimate ET from years 2017 through 2019 at a saturated, riparian end-member site. Owing to complexities in near surface atmospheric structure such as stable boundary layers over snowpack and shallow terrain driven flow from surrounding landscape features, energy flux and ET estimates were limited to the warm season when energy closure residuals from the eddy-covariance system were reliably less than 30%, a threshold commonly used in eddy covariance energy flux estimation. The resulting ET estimations are useful for constraining water budget estimates at this energy-limited site, which uses groundwater for up to 84% of ET in the summer months. We also compared East River ET magnitudes and seasonality to two other flux towers (Niwot Ridge, CO and Valles Caldera, NM), located in the Rocky Mountains. These data are useful for constraining ET estimates in similar end-member locations across the East River Catchment. Our results show that groundwater-fed ET is a significant component of the water balance and groundwater may supply riparian ET even during low-snow years.
AB - Despite the importance of headwater catchments for the water supply of the western United States, these regions are often poorly understood, particularly with respect to quantitative understanding of evapotranspiration (ET) fluxes. Heterogeneity of land cover, physiography, and atmospheric patterns in these high-elevation regions lead to difficulty in developing spatially-distributed characterization of ET. As the largest terrestrial water flux behind precipitation, ET represents a significant fraction of the water budget for any watershed. Likewise, groundwater is the largest available freshwater store and has been shown to play a large role in the water balance, even in headwater systems. Using an eddy covariance tower in the East River Catchment, a Colorado River headwaters basin, we estimated water and energy fluxes in high-elevation, complex systems to better constrain ET estimates and calculate overall water and energy budgets, including losses from groundwater. We used the eddy covariance method to estimate ET from years 2017 through 2019 at a saturated, riparian end-member site. Owing to complexities in near surface atmospheric structure such as stable boundary layers over snowpack and shallow terrain driven flow from surrounding landscape features, energy flux and ET estimates were limited to the warm season when energy closure residuals from the eddy-covariance system were reliably less than 30%, a threshold commonly used in eddy covariance energy flux estimation. The resulting ET estimations are useful for constraining water budget estimates at this energy-limited site, which uses groundwater for up to 84% of ET in the summer months. We also compared East River ET magnitudes and seasonality to two other flux towers (Niwot Ridge, CO and Valles Caldera, NM), located in the Rocky Mountains. These data are useful for constraining ET estimates in similar end-member locations across the East River Catchment. Our results show that groundwater-fed ET is a significant component of the water balance and groundwater may supply riparian ET even during low-snow years.
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U2 - 10.1002/hyp.14449
DO - 10.1002/hyp.14449
M3 - Article
AN - SCOPUS:85123804044
SN - 0885-6087
VL - 36
JO - Hydrological Processes
JF - Hydrological Processes
IS - 1
M1 - e14449
ER -