Happy start to the water year! (I'd never heard of it either)
Posted by David Brooks | Tuesday, October 2, 2012
Oct. 1 was the start of the "water year" - did you celebrate?
As I learned from CoCoRaHS, the crowdsourced precipitation-gathering site that I've been a part of for a year, hydrologists use that rather arbitrary date as the aquatic equivalent of the fiscal year. From the CoCoRaHS blog:
The water year is an approximation for the best consecutive 12 months that span the "water storage/water usage" hydrologic cycle. The water year cycle is particularly obvious in the Rocky Mountains and western U.S. where snow begins to accumulate at high elevations in October and doesn't melt and run off until next spring and summer. But this same important annual cycle takes different forms across the entire country.
Another way to think of the Water Year is the resting/replenishing season followed by the water consuming season where vegetation grows, crops are grown and then harvested. For much of the country, the months of October through March are months where precipitation from the sky exceeds evaporation from the ground. This means that soil moisture and ground water can recharge. The next spring temperatures will warm again, plants will come back from dormancy and once again evapotranspiration will surge.
I'll soon be getting a report about the readings at my house over the past water year, so I can bore you - er, enlighten you - with them one of these days.