Great Lakes Observing & Forecasting Systems

Improving Runoff Estimates in the Great Lakes Basin

Overview and Objectives

GLERL and CILER provided support, from 2012-2014, to the International Joint Commission (IJC) during the final phases of the International Upper Great Lakes Study (IUGLS) on calculating historical Great Lakes basin runoff estimates, and for establishing a cornerstone for future (post-IUGLS) research on improving those estimates. In addition to serving as an integral component of the Great Lakes water balance, runoff estimates serve as the backbone for regional ecosystems research.

As an extension of that work, GLERL and CILER continued to support the IJC’s need for understanding future water supplies in the Great Lakes by working to develop a new historical record of monthly runoff, over-lake evaporation, over-lake precipitation, and connecting channel flows. The primary objective of this work is the continued development of a new statistical model, which has been previously drafted strictly for Lakes Superior and Michigan-Huron and the time period 2005-2014, and extension of that model across all of the Great Lakes.

For this project, we characterize the relationship between runoff estimates and the other components of the water budget – precipitation, evaporation, channel inflows and outflows, diversions, and change in lake storage of water. We develop new estimates of runoff with respect to those variables, and quantify the uncertainty for those estimates.

We intend on extending the draft statistical model across all Great Lakes, and generating monthly estimates with quantified uncertainty for the period 1950 to present. The resulting database would be the first ever to effectively close the Great Lakes water balance while also reconciling different sources of data.


Gronewold, A.D., J. Bruxer, D. Durnford, J. Smith, A. Clites, F. Seglenieks, T. Hunter, S. Qian, V. Fortin. 2016. Hydrological drivers of record-setting water level rise on Earth’s largest lake system. Water Resources Research, 52(5), 4026-4042.

Gronewold, A.D., A.H. Clites, J. Bruxer, K. Kompoltowicz, J.P. Smith, T. Hunter, C. Wong, 2015. Great Lakes water levels surge. Eos, Transactions of the American Geophysical Union, 96(1), 14-17.


Gronewold, A.D. Great Lakes water levels, ice, and climate change: practical application of models. Presented at the School of Natural Resources, University of Michigan. Ann Arbor, MI (USA). January 2016

Gronewold, A.D., J. Bruxer, J. Smith, T. Hunter, V. Fortin, A.H. Clites, D. Durnford, F. Seglenieks. Aggregating hydrometeorological data from international monitoring networks across Earth’s largest lake system. December 2015. American Geophysical Union Fall Meeting, San Francisco, CA (USA).

Gaborit, E., B. Tolson, V. Fortin, A.D. Gronewold, L.M. Fry, T. Hunter. The Great Lakes Runoff Intercomparison Project (GRIP): Phase II, Lake Ontario. December 2015. American Geophysical Union Fall Meeting, San Francisco, CA (USA).

Gronewold, A.D. Data analysis, inference, and model development for improving water resources management. November 2015. North Carolina State University, Department of Civil and Environmental Engineering Seminar Series. Raleigh, NC (USA).

Hunter, T. J. Smith, S. Qian, Gronewold, A.D., May 2015. Improving the historical record of the Great Lakes water budget. 2015 Annual Conference on Great Lakes Research, Burlington, Vermont (USA).

Principal Investigator(s):
Tom Johengen (CILER)

NOAA Technical Lead(s)
Andrew Gronewold (NOAA-GLERL)