California finally has a after three weeks of intense rain brought flooding and disaster declarations across much of the state. All that water is the result of nine 鈥渁tmospheric rivers鈥� 鈥� warm, water-heavy air drawn up from the tropics 鈥� and has taken the edge off a historic drought. But California is still grappling with how to manage the between wet and dry years predicted under climate change.
Even as the rain brought devastating floods and mudslides, leading to at least 20 deaths and possibly more than , it also provided 鈥渁 great elixir for the historic drought we鈥檝e had in California鈥�, says at the University of California, Merced.
The three years since 2020 have been the driest in California in more than a century, with 35 per cent of the state under and more than 80 per cent under severe drought conditions by mid-December, according to the National Integrated Drought Information System (NIDIS).
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With the storms finished as of 19 January, no part of the state was under extreme drought and the portion under severe drought had shrunk in half, according to the NIDIS. Nearly all of the state remained under moderate drought conditions, however.
at the California Department of Water Resources says the NIDIS classification system is based on non-irrigated Midwestern agriculture so doesn鈥檛 accurately reflect California鈥檚 heavily managed water system or snowpack. But she says the storms have improved drought conditions, with total precipitation this year now up to .
That water has brought reservoirs above average for this time of year, though these are kept around half full for flood control purposes during the current wet season. At three California reservoirs, managers are testing ways to rely on improved weather forecasts to safely store more water, says Jones.
The storms also left behind a mammoth snowpack already around a quarter larger than the average high point usually seen in April, though the amount of snow that will become runoff depends on a variety of factors such as the dryness of soil and the weather in 2023, says Jones.
Still, 鈥渇rom a surface water perspective, things are going to be good鈥�, says Abatzoglou. 鈥淲e鈥檙e not going to have a surface water drought this year in California.鈥�
Things are more complicated when it comes to the state鈥檚 groundwater, which has seen huge losses from a combination of drought and a century of over-pumping. 鈥淥ne year, no matter how wet, is not going to recharge those groundwater basins,鈥� says Jones.
There are numerous projects underway to capture more water from storms to recharge those aquifers, but even large-scale improvements probably won鈥檛 be enough to stop some farmland from being taken out of production to balance groundwater budgets, as has been mandated by the state, says at Sustainable Conservation, an environmental nonprofit in San Francisco.
And even with the recent deluge, California remains from the Colorado river, which has been depleted to record low levels due to a megadrought in the US Southwest. Less affected by the atmospheric rivers, the Colorado river basin has still seen above average snow recently, but it is nowhere near enough to fill extremely low reservoirs along the river, says Jones. 鈥淭hat is literally the proverbial drop in the bucket.鈥�
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