Months of heavy rain and snow have greatly improved drought conditions in California.
An October 2022 drought monitor map showed that large parts of California were experiencing an extreme or exceptional drought. The rest of the state was in severe drought, with very small parts in moderate drought or unusually dry.
However, a Feb. 28 map, after torrential rain and snow swept across the state, showed vastly different conditions. Most of the state is now classified as unusually dry, while 16.7 percent of the state is not affected by a drought at all. Some small parts are in moderate to severe drought.
California has been suffering from a drought for two decades. But in late February, heavy snowstorms hit the state, even in areas used to bone-dry conditions. An incredibly rare snowstorm warning was issued in Los Angeles as snow fell on areas of low elevation.
A historic amount of rain also fell on the state between December 26 and January 19, and as a result, many of the state’s reservoirs have experienced rising water levels.
Recent rain and snow has been a welcome source of rainfall for the state and provided some reservoir for its reservoirs.
said hydrologist Roger Bales, a distinguished professor of engineering at the University of California Merced news week: “This heavy snowfall will allow for seasonal storage and release water later in the season, closer to the period when it is needed for irrigation by downstream users. It will also release water after the main rainfall period is over; and for some rivers the large marginal dams may be able to catch some more water and store it for use even later in the season.
Rainfall also helps keep vegetation moist during the drier summer months.
“Once all the snow has melted, the top meter of ground dries up within a few weeks. This longer, wetter period may mean more growth for shallow-rooted undergrowth vegetation, which, if it dries up or dies, provides more fuel for wildfires,” Ballen said. “On the benefit side, this means that the potential stress on deeper-rooted vegetation such as coniferous forest is reduced. So the deep snowpack will mitigate the drought effect in the forest by replenishing the underground water storage reservoir in the soil and weathering bedrock later in the season.”
While rain and snow have been welcome of late, the state isn’t out of the woods just yet.
Although the state’s drought status has improved, it will take years of increased rainfall to completely eliminate the drought status. That’s because the drought has been going on for so long.
“It’s good to remind people that asking if the drought is over may be the wrong question. We welcome average or more rainfall years, with the caveat that large storms, particularly warm atmospheric flows, increase the risk of flooding,” Bales said.
“Also, think of California precipitation as a series of dry to average years interrupted by a smaller number of wet years. Then subtract a constant value from each annual rainfall amount to get a much more variable runoff amount. That means water consumption by spring forests is about the same every year, the rest is runoff. Even a moderately wet precipitation year can only be an average discharge year. Wet discharge years are much less common than dry or average discharge years.
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