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Study on El Nino, Sierra Nevadas and rain could help guide Arizona water management

By Nicholas Gerbis
Published: Thursday, December 14, 2023 - 1:33pm
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Water management in the drought-stressed West is complicated by the interplay between mountains and the El Niño-Southern Oscillation (ENSO).

Now, new research in the journal Nature Water clarifies how ENSO affects the West differently in the south than in the north.

The warming of waters in the central and east-central equatorial Pacific known as El Niño tends to bring wetter winters to Arizona and New Mexico but drier ones to Utah and Wyoming.

But how do the Sierra Nevadas — which tend to wring air dry as it climbs their western slopes, soaking California and leaving lee-side states with the dregs — mitigate ENSOs effects?

Using more than 150 years of river gauge data tied to elevation, the paper in shows southwestern winter wetness varied with El Niño intensity, like a volume knob.

But northern states, with their more complex topography, either saw changes or didn’t, like a light switch, regardless of the ENSO’s strength.

The findings could help guide water management in Arizona and the West in general.

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