CoreLogic has estimated that 5,895 single and multifamily residential properties with a combined reconstruction value (RCV) of $2.88 billion are at risk of flooding following the Pajaro River in Central California overflowing its levee.
On March 10, the water level in the Pajaro River surpassed its levee, leading to a breach and a partial collapse that resulted in the flooding of homes and agricultural lands in Pajaro and Watsonville, California.
According to CoreLogic, the elevated risk scores in Pajaro as well as southern and eastern Watsonville are due to the flat landscape of the floodplain surrounding the Pajaro River.
The firm notes that historically, Pajaro and Watsonville have been protected by earthen levees on the left and right banks of the Pajaro River, which were constructed in 1949, as per the U.S. Army Corp of Engineers National Levee Database.
The levees have been tested on several occasions since construction, having only failed once due to flooding in 1995. However, during each test, significant bank erosion occurred. In 1995, floodwaters seeped through the levee, causing erosion of the sides and eventually flowing over the levee.
CoreLogic’s estimate accounts for all at-risk homes and does not represent the number of homes that were actually flooded.
Single-family homes include standalone residential structures of less than four stories, mobile homes, duplexes, manufactured homes and cabins, while multifamily homes include apartments, condominiums and multi-unit dwellings with more than four units.
CoreLogic has additionally observed NOAA data that reported seven-day rainfall totals from March 8 through March 15 exceeded 20 inches in certain areas along the California coast and the Sierra Nevada Mountains.
Almost 10 inches of rain has fallen near San Luis Obispo and Santa Cruz, California, while approximately five inches of rain has fallen in San Francisco and Los Angeles.
CoreLogic states that heavy rainfall in urban environments often leads to flash flooding when wastewater management systems are overwhelmed.
Further, the continuous rainfall has saturated soils across the state, increasing the risk of landslides.
The firm writes, “Heavy and continuous rainfall in the more mountainous regions of California is especially dangerous due to recent wildfire activity since wildfire burn scars strip the plant matter that provides soil cohesion.
“When the soil in burn scars is saturated, the risk of landslides increases. Residents living downslope of recent wildfire burn scars should be on alert for potential landslides.”
