We need to step up our game on evaluating drought risk

elevated drought risk impact Feb 20 2022

The Department of Water Resources’ new California Water Watch website is a great new resource, however, the site appears to miss information on the rapidly developing drought.

The website displays statewide precipitation for the water year to date. It also displays a map of “Drought Risk Impacts” based on precipitation being less than 70% of average for the water year to date, and temperatures being greater than the 80th percentile. The map for February 20, 2022 is shown below:

elevated drought risk impact Feb 20 2022

Intuitively, the map appears to underestimate developing drought risk in the state. Climate scientist Daniel Swain explains why in a February 17, 2022 Twitter thread:

Given the kind of water whiplash we have seen this year, it seems essential to look at shorter time frames in evaluating drought risk. Yet the February 4, 2022 California Hydrology Update by DWR’s state climatologist, Michael Anderson, only states,

To date statewide for the current water year (October 1, 2021- September 30, 2022), precipitation is 104% of average, down significantly from the end of December when it was near 150% of average.

If California is going to manage for drought risk, we need to step up our game.

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