Determine the correct water year based on a calendar date.
Usage
calcWaterYear(dateVec)
Arguments
dateVec
vector of dates as character ("YYYY-DD-MM"),
Date, or POSIXct. Numeric does not work.
Value
numeric vector indicating the water year
Details
This function calculates a water year based on the USGS
definition that a water year starts on October 1 of the year before,
and ends on September 30. For example, water year 2015 started on
2014-10-01 and ended on 2015-09-30. See the USGS definition at
https://water.usgs.gov/nwc/explain_data.html.