on the subject of the Flood, it must be said, there are INNER evidences in the Bible itself that the flood was a local event, and yet I think that it was the only one that was able to destroy an entire branch of humanity (the "sons of God", i.e. adamites) in a while.
If you look into your Bible, the book of Genesis clearly states that the Nephilim survived the Flood. Since the Nephilim are "sons of man" and "sons of God" they are nothing but humans with different characteristics then the "sons of God" themselves, yet they belong in the human race. The Bible clearly states the Nephilim (=giants) were "heroes of old" probably admitting that they inspired the pagan pantheons for the future generations, and there's also written that they survived the Flood, or better is assumed in the words of Moses:
The Giants were on the earth in those days. And also after that, when the sons of God came to the daughters of men, and they bore sons to them, the same were the mighty men who were of old, the men of renown.
The same David will deal with Giants. Since only eight people were saved on the Ark (Noah and his family); since the Nephilim were not animals but humans, so they couldn't be included in the list of the creatures saved by God; and since a global flood assumes that every single peace of dry land was submersed in water, we must conclude that the flood wasn't global and that the Giants lived outside of the area invaded by the waters.
I also can prove you that one of the earliest exegetes of that biblical passage, Flavius Josephus, who has largely been used by the Church Fathers as a source of information on Jewish history, used to prove the authenticity of the Deluge with a passage from Nicolaus of Damascus dealing with a tradition that some survivors of the flood who found refuge on the mountains encountered a man who saved himself and his family abord an ark.
There is a great mountain in Armenia, over Minyas, called Baris, upon which it is reported that many who fled at the time of the deluge were saved; and that one who was carried in an ark came on shore upon the top of it; and that the remains of the timber were a great while preserved...
If your problem is the fact that these flood legends are present all around the world, my personal answer (not by authority, but by judgment) is that the Earth was highly damaged by the effects of the last Ice Age, when the ices melt and many local floods destroyed entire civilizations over a period of 3000-4000 years. All these episodes, connected with each other by the same cause (the melting of the ice and the consequent climatic change) were thus absorbed into the Genesis narrative taking the episode experienced by Noah as a type of all the quasi-simultaneous (well, on a geological scale) megafloods of his time. Although I classify myself as a Biblical literalist (that is I believe in every single episode of the Holy Scriptures as history) I know that God on purpose
used a language that can be generalized and allegorized so that we can understand spiritual truths, such as the symbology of the Ark which is a figure for Christ and the Church. Take it like these: there were hundreds of Noah all around the world, nevertheless all human civilizations were wiped out, one after the other, by the same climatic change.
Anyway, if your church - or better your spiritual father - demands from you that you take these episodes as literally as possible, you could and should; nevertheless, there are valid reasons to try and explain the Biblical events (in which, I repeat, I trust) in the light of archeological discoveries.
In Christ, Alex