calculate_wrf_mvg Module Function

    module pure elemental function calculate_wrf_mvg(self, h) result(theta_w)
        implicit none
        class(type_wrf_mvg), intent(in) :: self
        real(real64), intent(in) :: h
        real(real64) :: theta_w

        if (h < self%h_crit) then
            theta_w = self%theta_r + (self%theta_s - self%theta_r) * (1.0d0 + abs(self%alpha1 * h)**self%n1)**(-self%m1)
        else
            theta_w = self%theta_s
        end if

    end function calculate_wrf_mvg