compute_IRpop: Compute population living nearest to an intermittent river
In NaiaraLopezRojo/globalIRmap: What the Package Does (One Line, Title Case)

Compute total population and percentage of the world's population which live nearest to a river or stream reach predicted to be non-perennial.

1	compute_IRpop(in_rivpred, inp_linkpop, valuevar)

`in_rivpred`	data.table of model predictions for global river network. output from netpredformat.
`inp_linkpop`	absolute path to table identifying number of people living nearest to each river reach in the global river network.
`valuevar`	name of the column in `in_rivpred` by which to compute percentage of the population (i.e., column name that contains the predicted binary flow intermittence class for each river reach)