The Sensitivity of a Coupled Atmosphere-Hydrology Model at Lake George, NY to Changes in Land Surface Model Configuration and Stream Celerity

he Jefferson Project at Lake George, NY is a collaborative effort by IBM, Rensselaer Polytechnic Institute and The FUND for Lake George. Lake George is a narrow, dimictic lake of unusually high clarity and has been experiencing ecological changes in recent years with the influx of invasive species, increasing levels of salt from road de-icing and an anoxic zone within the lake is not fully understood. A core component of the project is to develop a system capable of real-time observations and interactive modeling of the atmosphere, watershed hydrology and lake circulation. Here we present recent results from a coupled atmosphere-hydrology model comprised of a configuration of the WRF-ARW model and a highly detailed stream network model derived from 2-m proprietary terrain data. Given the complexity of surface and subsurface water generation (especially when snow is present), we force the stream network model with output from a land surface model (LSM).

Local rainfall and stream gauge observations from individual rainfall events and extended periods are used to evaluate the accuracy of the coupled model. Runoff event timing is generally well predicted, however significant opportunities exist to improve the simulation of peak flow rates and total runoff volumes. Towards this end, we attempt to quantify the sensitivity of surface and subsurface water generation by the Noah LSM to variations in key parameters, and extend the analysis to the more sophisticated Noah-MP LSM. We also analyze how changes to the celerity of the >10,000 individual stream segments in the stream network control flow through the system and at stream gauge locations.