As per Kennedy's theory, critical velocity (V_c) in a channel is the mean velocity that is sufficient to prevent the channel from scouring and silting. Any velocity greater than critical velocity causes scouring in the channel and any velocity less than critical velocity causes silting in the channel.
    V_c = 0.55 m D^0.64
    Where m is the Critical Velocity ratio and D is the depth of flow
    Further, the Critical Velocity ratio (CVR) is the ratio of actual velocity (V_a) to critical velocity (V_c) in the channel.
    Now If,
    CVR > 1 i.e. V_a > V_c Scouring will occur.
    CVR < 1 i.e. V_a < V_c Silting will occur.
    CVR = 1 i.e. V_a = V_c There will be no silting and scouring.