Climate Change and Los Angeles Flooding

The recent rainstorms wreaking havoc across Southern California are waking many people to the fact that floods are not just a nuisance, but that they can be dangerous and life-threatening. A recent study (open access) by researchers at UCLA suggests that climate change is doubling the odds of a megaflood in California that would cost $1 trillion, displace millions and submerge parts of Los Angeles and Sacramento. The scientists estimate that such a flood is likely within the next 40 years, or just over the lifetime of current residents.

This type of flooding can occur from a variety of causes, including dam or levee failures, and overflowing rivers and streams. It can also result from the overflowing of underground pipes and the bursting of street and drain catch basins designed to carry floodwater away from urban areas. Flooding can be local, affecting just a neighborhood or community, or very large, impacting entire river basins and multiple states. The risk of such a disaster is exacerbated by the fact that the development of land can reduce flood-control capacity. In addition, climate change is increasing the intensity and frequency of extreme rainfall events.

If you live in an area that is prone to flooding can LA flood, there are steps you can take to prepare for a flood. Keep materials such as sandbags, plastic sheeting and lumber on hand to help protect your home. Stay tuned to local TV and radio for announcements about hazardous conditions. If you must travel, be extremely cautious and do not drive around barricades that are there for your protection. A foot of water can float vehicles and could quickly sweep you off the road.

A major flood can disrupt or even shut down utilities, emergency services, transportation and the economy, resulting in damage to property and loss of life. Approximately 105,574 properties in the City of Los Angeles are at a moderate risk for flooding and could be severely impacted within the next 30 years.

The most at-risk neighborhoods are clustered in the tangled jumble of urban neighborhoods intertwined with industrial zones that hug the Los Angeles River, which was excavated and lined with concrete 85 years ago to prevent flooding. But as the region grows and changes, so does the need for an updated river management strategy.

The new research, published in the journal Nature Sustainability, used an innovative computer flood modeling and mapping program called PRIMo to show in house-by-house detail the effects of a massive deluge on aging drainage systems throughout LA County. The UCI study team included UC Irvine scientists Jochen Schubert, Steven Davis and Daniel Kahl; grad student Nicola Ulibarri; and other university colleagues in Florida and Ohio.