Would the amount of rain in the Carolina’s this past week be enough to end the California Drought? Not even close!
Several recent news reports have stated that the rain that fell over North and South Carolina this past week would be enough to erase the California drought. this was based on comparing an estimated 11 trillion gallons that the Carolinas received this past week to an amount from a NASA study that also used an 11 trillion gallon figure needed for California. However the numbers don’t add up.
It’s been estimated that the average rainfall that fell across the Carolinas was 10.4 inches. With a total area for North and South Carolina of about 85,000 square miles that actually equates to about 15.5 trillion gallons. [Specifically 1” of water over 1 sq. mile= 17,378,560 gallons; times 10.4” of rain, times 85,839 sq. miles equals 15,514,285,403,136 gallons]
Now, looking at California. The statewide average rainfall for California is about 24 inches, and in round numbers the 4-year rainfall deficit is approximately a year’s worth of rainfall. Given the total California area of over 163,000 square miles that’s a phenomenal 68 trillion gallon deficit, or over four times the rain that fell on the Carolinas! [Specifically 1” over 1 sq. mile= 17,378,560 gallons, times 24” of rain, times 163,694 sq. miles equals 68,274,384,015,360 gallons]
Some of the confusion arises from last December's NASA study that had a headline of "Needed: 11 Trillions Gallons to Replenish California Drought". However, reading the entire article reveals the 11 trillion gallon amount was for only the Sacramento and San Joaquin river basins. And finally, it should be noted that to "end the drought" in some areas of California it may take more than a year's worth and in other areas less.
Update (10/9): Please note the rainfall amounts for California (above) are only to make up the deficit. To "end the drought" we would need to make up most of teh deficit, PLUS the normal rainfall of the winter of 2015-16, or another 24 inches. Bottom line, we would be looking at as much 8 times the rains that flooded the Carolinas.
Jan Null, CCM
Golden Gate Weather Services