code: def _lnqmed_corr(self, catchment1, catchment2):
          
          dist = catchment1.distance_to(catchment2)
          return self._dist_corr(dist, 0.2791, 0.0039, 0.0632)
docs: Return model error correlation between subject catchment and other catchment.
  
          Methodology source: Kjeldsen & Jones, 2009, fig 3
  
          :param catchment1: catchment to calculate correlation with
          :type catchment1: :class:`Catchment`
          :param catchment2: catchment to calculate correlation with
          :type catchment2: :class:`Catchment`
          :return: correlation coefficient, r
          :rtype: float