2020 Local Hazard Mitigation Plan

City of Irvine

Drought

Physical Threat

Since the primary threat from drought is reduced water supply and availability, there are no foreseeable threats to any of the physical assets in the City. It is possible that any water delivery infrastructure is not used or used less than usual may fall into some degree of disrepair if maintenance is deferred. Lower water pressures may cause some aged water pipes to release rust particles into the water supply.

Social Threat

Droughts are unlikely to cause serious social threats to households in Irvine, though residents and business owners in the City may experience financial costs associated with water conservation efforts. Those who have less access to financial resources, such as low-income households or seniors, could be harder hit if higher water fees are imposed during a severe drought event.

Other Threats

A typical drought is not anticipated to lead to any outages in service in Irvine. An exceptional drought, however, may lead to restricted water use for residents or businesses in the City. Trees that are not properly adapted to lower levels of irrigation could perish, which would alter the City’s aesthetic appearance. For more specific information on tree health, please refer to Tree Mortality discussion under Diseases and Pests. Any open spaces with extensive lawns may start to die, turning brown in color, which could discourage residents from using these parks and open spaces.

Flooding (Sea Level Rise)

Physical Threat

Portions of the City are located within the 100-year flood zone (1.0% Annual Chance of Flooding) and the 500-year flood zone (0.2% Annual Chance of Flooding). Any physical assets located within these mapped boundaries can expect to be inundated if enough precipitation were to fall exceeding the storm drain infrastructure design capacity in these areas. Electronic or mechanical equipment on the ground could become waterlogged and nonfunctional. The City has several key underpasses beneath major freeways and rail lines, that if flooded, could impact circulation throughout the City. In addition, the City has key locations along Sand Canyon Avenue, Jamboree Road, Culver Drive, and Jeffrey Road that require pump stations to ensure these underpasses do not fill with water. Figure 4-4 identifies the 100-year and 500- year FEMA flood zone designations. Table 4-5 identifies the physical assets in Irvine located within the 100-year flood zone. Assets include 55 bridges and 3 City Recreation Support facilities. Potential losses associated with this flood zone could amount to over $130 million. This estimate also includes three assets that have the potential to be impacted by 1 meter of sea-level rise. These three bridges are located along San Diego Creek and have a replacement value of over $40 million. In addition, Table 4-6 identifies the additional assets located within the 500-year flood zone, which account for six CFs and two FOC that account for over $12.5 million in additional assets exposed to flooding within the City.

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