Submitted to: Trans American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 11/7/2005
Publication Date: 12/15/2005
Citation: Bales, R.C., Molotch, N.P., Marks, D., and Small, E.E. 2005. Integrated snow, soil and water-balance measurement strategy for multi-scale environmental observations in mountain areas. abstract H34D-04, Eos, Transactions of the American Geophysical Union, 86(52):F829
Technical Abstract: The building of multiscale environmental observatory networks is a critical step in addressing the woefully inadequate observational infrastructure and understanding of mountain water balances. These networks will support science questions that need estimates of water reservoirs and fluxes at the point, hillslope, headwater catchment and basin scales. This strategy will necessarily integrate both ground- and space-based data, using a coherent approach to measure fluxes of water and nutrients from bedrock to boundary layer. At the point scale multiple strategies can provide accurate estimates of rainfall, snow depth and soil moisture; though snow water equivalent and snowmelt remain challenges, in part due to the spatial heterogeneity of the energy balance, topography, and interactions between vegetation, snow and soil. The spatial distribution of snow is perhaps the best understood, measurable quantity at hillslope to headwater catchment (> 1 km2) and at basin scales (>100 km2) using a blended satellite and ground-based measurement strategy, though significant measurement challenges remain at intermediate scales. Comparable understanding for soil moisture, rainfall and water use by vegetation have yet to emerge, however we are testing approaches that build on what we have learned from prototype snow, soil moisture and sap-flow arrays. For example, the gap between the scale of a ground-based array and that of visible/infrared satellite data (0.25-1.0 km2) is one that is amenable to various interpolation methods in complex terrain; however satellite-based information on soil moisture is generally available only at a much coarser resolution (>100 km2). A coherent, integrated measurement system with carefully placed instrument clusters that measure atmospheric fluxes, snow depth, energy, and melt, soil moisture, and groundwater fluxes will provide information on how these processes are coupled, and how they vary with topography, vegetation, and soil characteristics. Extending these sites across a range of elevations in transects will provide information on how to scale snow and hydrologic processes from hillslope to larger scales. Within each cluster, randomly placed nodes to measure these properties at the same point provide an indication of how these quantities vary with slope, aspect, location in canopy, and soil characteristics. At larger scales, measurement sites should include end-member conditions to capture the heterogeneities that can lead to hydrologic extremes.