Though the water levels cross one section are almost equal , the velocities differ greatly . at the some cross - section , the velocity in the in the quirk may be double as that on the floodplain . the water surface will rise hi the southern branch because of the improper diffluence ratio , if using the designed diffluence col 淮河入海水道河口段水位值橫向分布相差無幾,而流速的橫向變化較大,泓灘平均流速差最大可達一倍以上,在現有的分流口設計條件下,若按設計的南北汊分流比,南分流口有壅水現象發生,如果南汊分流增大到800m ~ 3 / s左右時,則水流較為通暢。