In a river valley system floods can be expected, right now Louisiana in the USA is experiencing serious flooding.
But in pre-history there may well have been catastrophic floods that affected our primitive ancestors. Melting ice as ice-age epochs (never mentioned in the Bible-ever wondered why?) came to their end and the ice melted must have killed whole areas of early humans.
Another theory, that accounts for the flood memories of West Asian peoples is now known as the Black Sea Deluge hypothesis. In brief (from the National Geographic web-site) states:
Quote:" Columbia University geologists William Ryan and Walter Pitman wondered what could explain the preponderance of flood legends. Their theory: As the Ice Age ended and glaciers melted, a wall of seawater surged from the Mediterranean into the Black Sea.
• During the Ice Age, Ryan and Pitman argue, the Black Sea was an isolated freshwater lake surrounded by farmland.
• About 12,000 years ago, toward the end of the Ice Age, Earth began growing warmer. Vast sheets ofice that sprawled over the Northern Hemisphere began to melt. Oceans and seas grew deeper as a result.
• About 7,000 years ago the Mediterranean Sea swelled. Seawater pushed northward, slicing through what is now Turkey.
• Funneled through the narrow Bosporus, the water hit the Black Sea with 200 times the force of Niagara Falls. Each day the Black Sea rose about six inches (15 centimeters), and coastal farms were flooded.
• Seared into the memories of terrified survivors,the tale of the flood was passed down through the generations and eventually became the Noah story.
Reference: http://www.nationalgeographic.com/blacksea/ax/frame.html - if this concept is of interest, there are more pages to explore.