Soaⁿ-niā (山岭), iā thang kóng pun-chúi (分水), sī hun-kheh kīn-oá liû-he̍k ê tē-lí ê chū-jiân kài-soàⁿ. Soaⁿ-niā tû-liáu sī tē-lí-siōng ê kài-soàⁿ, iā tiāⁿ-tiāⁿ sī chèng-tī-siōng ê hun-kài-soàⁿ.