At Los Alamos National Laboratory, we are coupling a series of models that address the multitude of physical processes and temporal and spatial scales necessary to calculate the current and future water resources within a river basin. These models include the Regional Atmospheric Modeling System (RAMS), which provides meteorological variables and precipitation to the Simulator for Processes of Landscapes, Surface/Subsurface Hydrology (SPLASH). SPLASH partitions precipitation into evaporation, transpiration, soil water storage, surface runoff, and subsurface recharge. The runoff is collected within a simple river channel model and the Finite Element Heat and Mass (FEHM) subsurface model is linked to the land surface and river flow model components to simulate saturated and unsaturated flow and changes in aquifer levels. We are currently simulating the upper Rio Grande Basin from its headwaters in the San Juan Mountains of southwestern Colorado to Cochiti Reservoir, near Albuquerque, New Mexico.
The headwaters of the Rio Grande are fed primarily by snowmelt from winter storms, and the lower portions of the river accumulate runoff from thunderstorms of the summer monsoon season. These precipitation processes are tied to the complex topography in and surrounding the basin and, thus, the regional climate strongly influences the flow in the river. Changes to the regional climate could significantly affect water resources in the Rio Grande Basin.
This paper will focus on the evaluation of the precipitation fields predicted by the RAMS model over the coarse of the 1992-1993 water year. The evaluation includes comparing the model predictions to the observed precipitation as reported by Cooperative, SNOTEL, RAWS, and National Weather Service reporting stations. To do this, we interpolate the model fields to the location of each observation. We compare accumulated, water-equivalent precipitation for each month and a time correlation is also performed to determine if the model predicts the precipitation on the same day as was observed. These results will be presented for different areas within the basin and for all seasons.