Streamflow Response to Atmospheric Rivers in California's Russian River Basin

This study aims to better understand the variance within the streamflow response to atmospheric rivers (ARs) in California’s Russian River basin by extending earlier work on the hydrometeorological impacts of ARs. ARs can provide up to 50% of water year (WY; October 1 – September 30) precipitation in California and are associated with many of the large, damaging flood events in the western U.S. The Russian River basin, with unregulated inflow from Austin Creek, is a prime study area due to the wide array of observing systems including atmospheric river observatories, rain and streamflow gauges, a booming agricultural industry and the presence of coastal mountains enhancing precipitation effects in this area. For WYs 2008 – 2016, 96-hour composite time series of Austin Creek streamflow were analyzed to better understand the relationship between stream volume and the integrated upslope water vapor flux at Bodega Bay, CA. By evaluating the effects of 116 AR events by duration and runoff intensity, this study shows that shorter duration AR events (8-15 hours) were more likely to be preceded or followed by another short duration AR compared to longer duration (greater than 24 hour) events. These families of ARs, or successive AR events, enhanced the streamflow response of these individual storms, ultimately being of the order of magnitude of the average, single longer duration, AR event. We expect by exploring the large-scale dynamical aspects of extreme, greater than 28 cms, discharge rate events, preferences in the atmospheric set up were favorable to families versus single ARs and large versus small streamflow response ARs.