  I will prove a recurrence theorem which says that any $H^s$ ($s>2$) solution
to the 2D inviscid channel flow returns repeatedly to an arbitrarily small
$H^0$ neighborhood. Periodic boundary condition is imposed along the
stream-wise direction. The result is an extension of an early result of the
author [Li, 09] on 2D Euler equation under periodic boundary conditions along
both directions.
