This writer offers an excellent analysis of the argument between a local and global flood. Old earthers argue that if there even was a flood, it was a minor local flood in the Mesopotamian valley. You can see from the critique below, that this local flood view is in direct conflict with scripture and the evidence seen today
From the article:
In sum, believe the local flood theory faces many more practical issues than the global view, not the least of which is the lack of support from Scripture.
Any support found for the local view seems to be based on spurious hermeneutics and fallacious exegesis, and the same is true of passages leveled against the global view. Further, as we saw, the local view faces what I think to be insurmountable difficulties both Scripturally and scientifically, and the assumptions involved are the real crux of the matter.
Once we abandom uniformitarian assumptions, the global view is not only possible, but seems to best and most reasonably explain the data from science, Scripture, and even culture.
I therefore conclude that, with respect to the Noachian Deluge, Scripture emphatically says “global!”