If events open the floodgates to something, they make it possible for that thing to happen much more often or much more seriously than before.
例句
A decision against the cigarette companies could open the floodgates to many more lawsuits...不利于煙草公司的裁決可能引發更多的官司。Would it not set a precedent? Would it not open the floodgates?難道它不會成為先例嗎？難道它不會引發更多類似的問題嗎？