A Streamflow Routing Model for the Goddard Earth Observing System Model (GEOS) Climate Modeling System

Yujin Zeng, Goddard Earth Sciences Technology and Research II

The Earth’s nonglacial land surface can be represented as a spatial field of juxtaposed hydrological basins and interbasins (“catchments”) as derived from global, 30 arcsecond topography data. The hydrological catchment is the basic element upon which the land surface model’s physics are designed. At every model time step, the land surface model generates two types of runoffs: surface runoff (representing precipitation water that runs immediately over the surface to streams or somewhat more slowly to the streams via interflow, though that latter delay is not explicitly calculated) and baseflow (representing transport of water from the water table to the streams). The runoff water so generated is the water to be routed through the network all the way to its destination: the ocean or an inland sea. In the current version of GEOS Climate Modeling System, the runoff water is directly added to its destination (i.e., the ocean). That means the routing of the water in the streams is not explicitly simulated and the model cannot output the discharge of streamflow. To improve the model to include the river network system, we intend to design a river routing module and implement it to GEOS Climate Modeling System in this project.