The flooding now occurring in Louisiana and Mississippi is a stark reminder of how disruptive and potentially dangerous floods can be. Today the National Oceanic and Atmospheric Administration (NOAA) launched a new simulation tool – the National Water Model (NMW) – running on NOAA’s new Cray XC40 supercomputers that greatly extends and enhances NOAA’s ability to forecast river flooding.
The new model uses data from more than 8,000 U.S. Geological Survey gauges to simulate conditions for 2.7 million locations in the contiguous United States. The model generates hourly forecasts for the entire river network. Previously, NOAA was only able to forecast streamflow for 4,000 locations every few hours.
“This is our first foray into high performance computing and it’s a very big step for us,” said Thomas Graziano, director of NOAA’s new Office of Water Prediction at the National Weather Service. “We’re able to get much higher fidelity of the models as well as the range.” For comparison, there are thirteen regional centers tracking ‘catch basin’ flow, and on average the resolution for their models is about 420 square miles while NWM is able to achieve roughly one square mile granularity.
The underlying technology for the model was developed by the National Center for Atmospheric Research (NCAR). NOAA developed and implemented the model along with NCAR, the Consortium of Universities for the Advancement of Hydrologic Sciences, the National Science Foundation, and federal Integrated Water Resources Science and Services Consortium partners, said Graziano.
In January NOAA deployed two new Crays – nicknamed Luna and Surge – each with 2.89 petaflops capacity. The new model runs on one at a time, depending on availability. “Currently we reserve about eight percent of the Cray’s capacity for our work,” said Graziano. The new model allows NOAA to issue forecasts for coastal areas as well as inland.
Initially, the model will benefit flash flood forecasts in headwater areas and provide water forecast information for many areas that currently aren’t covered. As the model evolves, it will provide “zoomed-in,” street-level forecasts and inundation maps to improve flood warnings, and will expand to include water quality forecasts. Longer term, said Graziano, NOAA plans to connect the NMA system with a similar system monitoring estuary conditions.
“With a changing climate, we’re experiencing more prolonged droughts and a greater frequency of record-breaking floods across the country, underscoring the nation’s need for expanded water information,” said Louis Uccellini, Ph.D., director of the National Weather Service. “The National Water Model will improve resiliency to water extremes in American communities. And as our forecasts get better, so will our planning and protection of life and property when there’s either too much water, too little, or poor water quality.”