I previously stated my personal theory on the whole Noah and the flood matter and I am equally at peace with those who take the story literally and those who take it as allegorical/metaphor.
But let me play devil's advocate here.
1. All the science in the world cannot be certain of what the climate or temporary state of the world was at the time of Noah. And while the scientific consensus would be that a global flood was unlikely, at least the third day of Creation in Genesis 1, we can be sure that there were floods that to the unscientific eye and mind would look like they went on forever.
2. The issue of whether all the critters on Earth at that time could have fit on the Ark and whether there would have been room for feed for all of them is moot since with God, all things are possible.
3. The issue of whether a global flood of Biblical proportions would have contaminated all the arable land with salt is also moot because a) it was God's flood and therefore He would dictate whether it would or would not do harm and b) the seas might not have been so salty at that time. Or c) crops then might have been more salt resistant--there is scientific research going on right now to develop large scale commodity crops (wheat, corn, barley) that would thrive when irrigated with undiluted sea water. There are already crops that thrive using diluted sea water.
It is inevitable that as the global population continues to increase, the time will come that we will need fast, effective, economically feasible ways to produce potable water from the oceans.
In other words, it is interesting to think about, even to debate the pros and cons of it all, but there is plenty of argument and thought on both sides that we need not think poorly of the other person and/or his argument on the topic.