Debris Flow Mitigation Master Plan: 5 Watersheds Study Montecito, California

The January 9, 2018 debris flows devastated the community of Montecito resulting in 23 fatalities, destroying or damaging over 400 homes, and closed Highway 101 for twelve days.  A community member and survivor of the debris flows, Curtis Skene promoted the idea of developing debris basins to protect the community.  He shepherded the development of the Randall basin concept by bridging the Randall Road neighborhood with the County of Santa Barbara Flood Control and rallied support from County Supervisors.  Mr. Skene founded the Partnership for Community Renewal, a non-profit organization that will fund the mitigation study with the objective to develop a master plan and partner with the community and government to mitigate another 1-9 type event.

The debris flow mitigation study consists of geomorphic, hydrologic, hydraulic, sedimentation, and mudflow analyses of all five Montecito watersheds to identify sites for development of debris basin systems and sites for creek channel mitigation to improve flow conveyance.  Recommended debris basin structures will capture and retain the coarse boulder and vegetative debris.  By removing the coarse fraction of debris from the flows, the finer fraction of sediment can be conveyed with less impacts to downstream residential structures.

Preliminary analyses using GIS software tools includes construction of 3-D hillshade maps for mapping of geomorphology; detection of ground surface changes comparing historical LiDAR with the 2018 LiDAR; and construction of creek channel thalweg profiles to assess past and present creek gradients.  Preliminary findings confirm that the location of the Randall Road basin is an ideal site on San Ysidro Creek based on thalweg gradients and historical impacts.  Integrating GIS and spatial data analyses into the study facilitates the identification of debris deposition sites, potential debris basin locations, and creek channel mitigation sites.

Track A
Location: ASC 140 "Viz Hall" Date: December 6, 2019 Time: 10:30 am - 11:00 am Larry Gurrola, Ph.D.