Return multiplier for L-CV weightings in case of enhanced single site analysis.

        Methodology source: Science Report SC050050, eqn. 6.15a and 6.15b

def _l_cv_weight_factor(self):
        """
        Return multiplier for L-CV weightings in case of enhanced single site analysis.

        Methodology source: Science Report SC050050, eqn. 6.15a and 6.15b
        """
        b = 0.0047 * sqrt(0) + 0.0023 / 2
        c = 0.02609 / (self.catchment.record_length - 1)
        return c / (b + c)