Abstract
WATER RESOURCES RESEARCH,
VOL. 45,
W10413,
13 PP., 2009
doi:10.1029/2009WR007733
On the role of groundwater and soil texture in the regional water balance: An investigation of the Nebraska Sand Hills, USA
School of Natural Resources, University of Nebraska, Lincoln, Nebraska, USA
Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
School of Natural Resources, University of Nebraska, Lincoln, Nebraska, USA
Department of Geosciences, University of Nebraska, Lincoln, Nebraska, USA
Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
Partitioning of precipitation between evapotranspiration and runoff at the basin scale is primarily controlled by climate
and basin characteristics. Here we use the Budyko hypothesis to investigate the impacts of soil texture and groundwater (e.g.,
baseflow) on annual and long-term mean annual water balances of basins in a semiarid region located in and around the Sand
Hills region of Nebraska, USA. Native grasslands are dominant across the study area with soil textures dramatically different
for the Nebraska Sand Hills (primarily sand deposits) and the adjacent regions (mainly less permeable silt loam). For each
basin, long-term hydrologic and meteorological data are obtained, and a baseflow index is calculated using daily streamflow
data to quantify the groundwater contribution to streamflow. We found sound field evidence that suggests the control of soil
texture on mean annual water balance and the impact of groundwater storage on interannual variability of water balance at
catchment scales, which is usually seen at plot scales and in theoretical models. Our results show that compared to the basins
located in the adjacent regions, the Nebraska Sand Hills basins experience much higher long-term mean annual surface runoff
ratios (
/
) and thus lower ratios of (
−
)/
, where
is the long-term mean annual precipitation. The high baseflow index and its positive correlation with the ratio of
/
in the Sand Hills basins illustrate the role of lower (higher) evapotranspiration (recharge) rates. On annual time scales,
the baseflow-dominated basins exhibit a negative relationship between annual (P − R) / P and annual aridity index (i.e., the ratio of annual potential evapotranspiration to annual precipitation), which deviates
from the original Budyko hypothesis. Moreover, with decreasing baseflow index, this negative relationship gradually transits
into a positive relationship that follows Budyko's curves. Our results suggest that soil textural differences may strongly
modify the impact of climate on regional water balance. These findings may have important implications for managing water
resources under a fluctuating climate.
Received 13 January 2009; accepted 4 August 2009; published 9 October 2009.
Citation: (2009), On the role of groundwater and soil texture in the regional water balance: An investigation of the Nebraska Sand Hills, USA, Water Resour. Res., 45, W10413, doi:10.1029/2009WR007733.
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