Snowfall, accumulation and melt are important hydrological processes in watersheds at high altitudes or latitudes. In many western states, snow melt accounts for a large percentage of the spring runoff that serves as water supply to reservoirs, urban populations and agricultural activities. Our group is pursuing new methods for incorporating snow hydrology into distributed models over complex terrain through theoretical developments, model development and testing with field and remote sensing data sets. Snow hydrology is quite complex and involved both mass and energy balance calculations over a time-varying snow pack which is influenced by spatial location in the watershed, interaction with vegetation and redistribution by winds. We seek to accurately capture snow dynamics at a point and over a domain as the spatial pattern of snow cover area is readily observable from remote sensing.  
     
   
 
  Our study area is located in the Jemez Mountain of northern New Mexico which includes the Valles Caldera National Preserve. The 65 km2 reserve has been the site of a varied history, including cattle ranching, logging and geothermal development. Jemez Mountain is an extinct and massive rhyolitic volcano with its collapsed caldera and interior resurgent domes. Ecosystems in the Valles Caldera consist of ponderosa pine, mixed conifer, montane grasslands and high altitude wetlands which co-exist over short distances. During the winter season, high snowfall amounts lead to well established snowpacks and snowmelt runoff serving as perennial baseflow to the Jemez River. Snow hydrology in the Valles Caldera is studied through in-situ measurements, field sampling campaigns and numerical modeling. The snow accumulation, and melt occurring in the Valles Caldera are representative of the southern Rocky Mountains.  
     
 
  In order to properly simulate mountain hydrological processes during the winter season, our group is constructing a distributed snow module for the tRIBS model. A hierarchical approach is being taken with models of different complexity, ranging from a restricted-degree day method to a full energy balance approach. The distributed snow accumulation, drift and melt module will incorporate explicit interactions with the unsaturated zone, vegetation, and runoff production mechanisms. The snow component will allow modeling the springmelt runoff in the basin, and can be validated streamflow observations, snow depth and density measurements and with remote sensing observations of the snow cover area.  
     
 
               
       
Snow hydrology hydrology in interior of the Valles Caldera, Jemez Mountain.
 
Spatial map of root-zone soil moisture derived from preliminary simulations in the Jemez River and Upper Rio Puerco.