Modeling Transport of Oil from the Refugio Beach Oil Spill

Abstract

2017-288 ABSTRACTThe Refugio Beach oil spill originated from a pipeline break on 19 May 2015 near Refugio State Beach, which is located approximately 20 miles west of Santa Barbara, California. An estimated 500 barrels (21,000 gallons) of crude oil flowed from the shore side of Highway 101 into the Pacific Ocean. Trajectory and fate modeling of the oil were provided to the Incident Command to support the response. Several factors were particularly challenging for oil spill modeling in this incident. The spill entered the ocean through the surf zone, a distinct dynamical region with variability on small spatial and temporal scales, which coastal circulation models generally do not resolve. The regional winds were also highly variable and in some locations forecast models did not reflect the on-scene observations. A final complication was the presence of numerous natural oil seeps in the region. This posed challenges both for model initialization and validation of modeling results.In the days following the spill, above-background levels of tarballs were observed coming ashore on various beaches remote from the spill. Chemical analyses indicate that some of the tarballs likely originated from the spill. Hindcast modeling of the spill was conducted to examine transport between these locations and the spill source. Modeling simulations showed regional connectivity in approximately the correct time frame between the spill site and beaches in Ventura County and Santa Monica Bay.