An Operational Coupled Modelling and Observing System Testbed to Assess Water Quality in the Lake George, New York Watershed

Abstract:

Lake George is a glacial, oligotrophic water body of unusually high clarity in upstate New York. It has experienced ecological changes recently with the influx of invasive species, increasing levels of salt from road de-icing agents as well as nutrient loading from storm water runoff, and the accompanying deterioration of water quality.

To study these changes, we developed a system to observe and model the atmospheric, hydrological, hydrodynamic and ecological aspects of the lake and the surrounding region. This capability is an operational testbed for addressing related issues in lake watersheds, estuaries and similar ecosystems. It includes real-time access to over 500 sensors that support adaptive sampling driven by forecasted conditions from the models. These data are used for model verification, and to improve model initial conditions via data assimilation. To enable data sharing and software reuse, community data models have been adopted, which also drive geometric modelling to enable fixed and interactive visualizations.

The modelling starts with numerical weather prediction to 333m horizontal resolution for forcing lake circulation and runoff models using the community WRF-ARW model. To address hydrological forcing of the lake, the community WRF-Hydro model is used employing gridded stream routing at 41m resolution. The model has been extended for the transport of dissolved salt.

For lake circulation, a community hydrodynamic model, SUNTANS, has been deployed with variable horizontal resolution from ~27m to ~70m. It forces a simple ecological model, which considers nutrients, phytoplankton, zooplankton, small and large detritus, and oxygen to evaluate relative growth of phyto- and zoo-plankton.

We will present an overview of the models and the observing system along with the results to date. This will include extensions to other lake watersheds and evaluating signatures for harmful algal blooms.