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...不利于烟草公司的裁决可能引发更多的官司。Would it not set a precedent? Would it not open the floodgates?难道它不会成为先例吗?难道它不会引发更多类似的问题吗?