Rivers pose one of the most challenging environments to quantify as they contain elements of both land and water. Their dynamical scales are small in size relative to traditional ocean processes, and are ever-changing in their position and character. To compound the problem, many riverine environments of interest to the US Navy are inaccessible or denied and typically have very little, if any, known information.

To address the operational needs of the Navy in rivers, a River Simulation Tool (RST) is being developed that brings together satellite imagery, hydrodynamic and hydrological modeling. One component of the RST requires estimation of upstream discharge. To do this we use NASA's Land Information System (LIS) to generate the surface runoff and subsurface baseflow. We force the land surface model within LIS using satellite-derived precipitation. Finally, we generate the upstream discharge by routing the runoff and baseflow using a river routing model from the University of Washington. While this approach has been demonstrated on a large scale (0.5 deg resolution) for the combined Ganges/Brahmaputra River Basin on the Indian Sub-Continent (Brown, 2007), our challenge here is to apply these techniques to a small scale regime (~1 km). As a first test case we chose the local Pearl River (Mississippi/Louisiana) watershed. Preliminary results will be shown.