Happy Water Year! (The hydrologic, not astrologic, calendar )
Posted by David Brooks | Tuesday, October 1, 2013
I got this message today from the precipitation-watching organization Community Collaborative Rain Hail Snow network - something interesting for those of you tired to ordinary calendars:
October 1st is a special day on the CoCoRaHS calendar. It is the first day of the 2014 Water Year!
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 cultivated 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. When next spring arrives, temperatures will warm again, plants will come back from dormancy and once again evapotranspiration will surge.