The best way to handle channel floods is do the following command:
/mode #channel +KRMNb p:*!*@*
these modes will nullify any flood attempt further from this point, the only " last flood " they can do is by parting or by quitting the server.
if your unsure on these modes then seek help in #ophelp - while your there it maybe also in your best interest that you seek chanop and ircop help against the flood.