The Oroville dam in California has been the cause of much concern over the past week, with torrential rain pushing it to its’ limits, leading authorities to evacuate over 180,000 people whose homes could be destroyed by a potential failure of the dam’s spillway system. Whilst the Oroville dam held-fast and the risk of a failure is considered to have waned, scientists have begun looking at the factors that started the situation in the first place.
Atmospheric rivers, which can be hundred kilometers wide and stretch across thousands of kilometers from the tropical oceans to the poles, and have been known to carry twenty times more water than the Mississippi River. These skyward rivers can release enormous amounts of water given the right conditions – like in the Oroville dam’s catchment zone. Apart from discharging large volumes of water, the rivers are responsible for some serious weather, including heavy winds, which have been known to cause even more damage than the rainfall itself.
In California, these atmospheric rivers account for almost half the state’s total annual rainfall, but do so in small bursts like the one witnessed earlier this week, making them a known event across the meteorological community. That being said, dam reservoir levels are meant to be kept at a manageable level in case of an atmospheric river event, but due to their unpredictable nature and scientists’ inability to accurately track them, situations like that at the Oroville dam are at risk of repeating themselves.
Hope isn’t lost though, researchers are currently exploring the connections between atmospheric river events and other climatic fluctuations such as El Niño / La Niña and the Madden-Julian oscillation, which can help make long-range, seasonal forecasts. Whilst these scientists are coming close to identifying potential markers, they warn that events of this kind could become more serious and more predominant as climate change worsens. It is expected that if the climate should continue its current trend, atmospheric rivers will hold more water and have worse environmental ramifications, making the display in California more of a warning sign of what is to come more so than anything else.