Randall Debris Basin
Channel: Sean Anderson
Date: 2024-02-26

The Randall Debris Basin in Montecito, California, serves as a critical infrastructure component for managing debris flow and flood risks in the lowlands of Montecito, particularly in the aftermath of future wildfires. Montecito, in southern Santa Barbara County, is particularly susceptible to mudslides and debris flows during periods of heavy rainfall (especially when we get more than 1" of rain in an hour) following wildfires that devegetate the hillsides.

On January 9, 2018 Thomas Fire-impacted hillsides combined with an atmospheric river to create historic debris flows which destroyed 6 of 7 homes in the 600 block of Randall Road and killing two people as San Ysidro Creek suddenly swelled with the flows.

This Randall Debris Basin is part of the region's larger flood control system implemented beginning in 2021 to mitigate these risks. Debris basins like Randall are strategically placed in areas prone to debris flows to capture sediment, rocks, and other debris carried by stormwater, preventing it from reaching downstream communities and infrastructure. 

The Randall Debris Basin features a large catchment area designed to intercept and trap debris-laden runoff from the adjacent hillsides during heavy rainfall events. Debris racks (brown metal structures perpendicular to the main channel) slow down and capture the large items (boulders, tree trunks, etc.) caught up in the flow while allowing water to gradually discharge downstream. Periodically these debris basins must be manually cleaned out to make room for future debris captures.