Forecast Verification of the 2017 Flooding at Lake Oroville Using the National Water Model

Northern California experienced multiple heavy precipitation events in early 2017, which filled the Lake Oroville Reservoir to maximum storage. The National Water Model (NWM) forecasts simulated streamflow nationwide and went operational in August 2016. This research involved testing both versions (1.1 and 1.2) of the model to see if either accurately predicted the flooding experienced at Lake Oroville. Coincidentally, NWM version 1.1 did not have Lake Oroville as a modeled reservoir, whereas version 1.2 included it, providing the opportunity to study how each version captured this event and modulated flow through and downstream of the lake. Comparisons of these model results to recorded streamflow observations and reservoir observations at Lake Oroville will be presented. Questions regarding how the reservoir behaved in the NWM and how said behavior tracked the reality of reservoir operation are explored. Potential insights toward improving the model will be discussed, as will implications of having an accurate model for affected communities and emergency officials.