stormevents - extract out storm events based on user supplied thresholds

This function will identify and extract storm event flow rates using HYDSEP
techniques (local minimum). The user needs to provide a time series of data,
the drainage area associated with the time series, a set of peak flow rates
to use, and a tolerance of the peak flow rate to be used. The original
usage of HYDSEP was meant to be used on daily mean flow rates, this
function uses maximum daily flow rates instead.

This function is dependant on two other functions I wrote you can download from Mathworks User community.

Further detail can be found in the function comments.