merge flow variable into analysis data frame and update iSpec with variable name
.mergeFlow(ct1 = ct1, iSpec = iSpec, gageID = gageID,
hydro.var = hydro.var, flow.detrended = flow.detrended)
analysis data frame
iSpec
"q" + USGS gage ID
averaging windows
data generated by detrended.flow. Default = flow.detrended.