This month, California has been ripped by several intense storms and many communities across the state have been flooded out. The L.A. Times reports at least 22 have died as a result of the flooding and landslides. Statewide, California has accumulated around 11.2 inches of rainfall.
These storms are known as atmospheric rivers, or ARs. ARs carry moisture up from the tropics into the atmosphere resulting in heavy rains, wind and flooding when they reach land. ARss occur every year, but it’s uncommon to find them arriving in succession like they have recently on the West Coast.
On an average year, California will receive one or two atmospheric river events. Nine atmospheric rivers have come in from the tropics between the end of December and January this year alone.
The United States Geologic Survey reported that such a storm is not a total surprise. During the winter months of 1861 and 1862, California experienced similar intense flooding, historically known as the Great Flood of 1862.
For decades it was thought an El Niño storm or polar winds caused the flooding, but today’s consensus is that it was likely another series of atmospheric rivers that swept in repeatedly over several weeks. While they could not predict when or where it could happen, it is clear that such storms are possible, and preparation is key.
The rain also comes as a much needed gift to drought stricken lands across the West. In the San Joaquin Valley, the drought has had a significant impact on the surrounding agricultural communities. According to the National Integrated Drought Information System (NIDIS), counties within the valley such as Kern and Tulare have seen an increase in their groundwater reservoirs. Currently, they are experiencing what is classified as a moderate drought.
While the rains have been a temporary boon for communities facing severe drought, it is unlikely to have long lasting benefits.
California will require increased stormwater infrastructure to collect and use the water for irrigation or drinking, something that researchers and scientists claim can help both the flooding and the water crisis.
Water sustainability practices such as permeable pavement or rainwater barrels are some of the popular ways to capture and retain stormwater. Across the state, these practices are starting to be implemented.
The National Oceanic and Atmospheric Administration (NOAA) predicts that climate change will likely cause atmospheric river events to become more common in the future. While they do not have a definitive answer for when or how heavy the next storm will strike, models using data from previous years show that we can expect storms such as these to become more frequent.
