Runoff - non-unique weights between sites and huc

calculate_geometric_runoff() assumes there is always one site with a maximum overlap with a huc, but sometimes sites tie in their degree of overlap (perhaps due to gages being retired and replaced?). This sets off an assertion in the function that .max() will return only one row. We need to figure out how to deal with gages that have the same weight (and data for both?).

example huc08:

'02070009'