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

def _lnqmed_corr(self, catchment1, catchment2):
        """
        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
        """
        dist = catchment1.distance_to(catchment2)
        return self._dist_corr(dist, 0.2791, 0.0039, 0.0632)