ˌʌnɪmpˈɛɹd ɹˈʌnɔf, ˈɔːlsoʊ nˈoʊn æz fˈʊl nˈætʃɚɹəl flˈoʊ, ɪz ɐ haɪdɹˈɑːlədʒi tˈɜːm fɚðə nˈætʃɚɹəl ɹˈʌnɔf əvə wˈɔːɾɚʃˌɛd ɔːɹ wˈɔːɾɚbˌɑːdi ðæt wʊdhɐv əkˈɜːd ˌʌndɚ kˈɜːɹənt lˈænd jˈuːs bˌʌt wɪðˌaʊt dˈæmz ɔːɹ daɪvˈɜːʒənz.
Unimpaired runoff, also known as full natural flow, is a hydrology term for the natural runoff of a watershed or waterbody that would have occurred under current land use but without dams or diversions.