The predicted consequences of global climate change continue to grow.
This concern is acute in arid and semi-arid regions of the world,
where competition for limited quantities of available fresh water
can lead to conflict. Coupled models of the atmosphere, land surface
and subsurface systems provide the prospect for accurate water resources prediction. This is possible because feedback between these systems is included in the coupled models. At the same time, increased spatial and temporal resolution is needed to determine the effects of land use and local impacts of climate variability on hydrologic response.
Los Alamos National Laboratory is developing a coupled modeling system for regional consequence assessments of climate variability. The components of the system include the Regional Atmospheric Modeling System (RAMS), which provides meteorological variables and precipitation to a high resolution land surface model, 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 routed through a river channel model, and a subsurface hydrology model is linked to the land surface and river flow model components to simulate saturated and unsaturated flow and changes in the groundwater.
The design and development of the modeling system will be described. This includes the software engineering tools necessary to identify model component interactions and their implementation on parallel processing computers. Key issues are 1) synchronizing the computations given differences in the rates of various processes, e.g. precipitation versus groundwater flow; 2) allocating processors and memory to pass information efficiently among the codes; and 3) flow of data between the components. The rationale and methods to upscaled or downscaled data passed between components are also discussed.
Model testing will be conducted over the Rio Grande Basin
which is characteristic of rivers in arid and semiarid environments.
This river system provides an essential water supply for the flora, fauna, and human populace along its course. The waters of the Rio Grande are strongly influenced by regional climate and could be vulnerable to climate variability. Data from the Rio Grande Basin are being collected into a data base to support model initialization and testing activities. Preliminary results from the coupled modeling system will be presented.