Mountain Hydrology of the Semi-Arid Western U.S.: Research Needs, Opportunities and
Challenges
* Bales, R (rbales@ucmerced.edu) , University of California, School of Engineering, Merced,
95344
Dozier, J , University of California, Bren School, Santa Barbara, 93106
Molotch, N , University of Colorado, CIRES, Boulder, 80309
Painter, T , University of Colorado, NSIDC, Boulder, 80309
Rice, R , University of California, School of Engineering, Merced, 95344
In the semi-arid Western U.S., water resources are being stressed by the combination of climate
warming, changing land use, and population growth. Multiple consensus planning documents
point to this region as perhaps the highest priority for new hydrologic understanding. Three main
hydrologic issues illustrate research needs in the snow-driven hydrology of the region. First,
despite the hydrologic importance of mountainous regions, the processes controlling their energy,
water and biogeochemical fluxes are not well understood. Second, there exists a need to realize,
at various spatial and temporal scales, the feedback systems between hydrological fluxes and
biogeochemical and ecological processes. Third, the paucity of adequate observation networks in
mountainous regions hampers improvements in understanding these processes. For example, we
lack an adequate description of factors controlling the partitioning of snowmelt into runoff versus
infiltration and evapotranspiration, and need strategies to accurately measure the variability of
precipitation, snow cover and soil moisture. The amount of mountain-block and mountain-front
recharge and how recharge patterns respond to climate variability are poorly known across the
mountainous West. Moreover, hydrologic modelers and those measuring important hydrologic
variables from remote sensing and distributed in situ sites have failed to bridge rifts between
modeling needs and available measurements. Research and operational communities will benefit
from data fusion/integration, improved measurement arrays, and rapid data access. For example,
the hydrologic modeling community would advance if given new access to single rather than
disparate sources of bundles of cutting-edge remote sensing retrievals of snow covered area and
albedo, in situ measurements of snow water equivalent and precipitation, and spatio-temporal
fields of variables that drive models. In addition, opportunities exist for the deployment of new
technologies, taking advantage of research in spatially distributed sensor networks that can
enhance data recovery and analysis.
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