sˈɪns ðiːz kˌælkjʊlˈeɪʃənz ɪnvˈɑːlv mˈɛni ɐsˈʌmpʃənz, ðeɪ tˈɛnd təbi mˈoːɹ ˈækjʊɹət fɔːɹ ˈiːðɚ smˈɔːlɚ wˈɔːɾɚʃˌɛdz ɔːɹ wɛn ɛkspɹˈɛst æz lˈɔŋɡɚ pˈiəɹɪəd ˈævɹɪdʒᵻz.
Since these calculations involve many assumptions, they tend to be more accurate for either smaller watersheds or when expressed as longer period averages.