Final answer:
Significant Nile floods with substantial effects on the irrigation systems occurred in the 15th century, including a low flood in 1200 CE and an early flood in 1479 CE.
Step-by-step explanation:
Floods in the Fertile Crescent were a common occurrence due to the unpredictable nature of the Tigris and Euphrates rivers. However, the floods mentioned in the provided excerpts primarily refer to those that affected the Nile in Egypt. Notable floods that took place include the disastrously low flood of 1200 CE, the unusual flood of 1479 CE arriving early, and floods in the 15th century that were significant for their impact on the irrigation systems.
These systems became impaired due to decaying and silting, leading to mismanaged water distribution, and ultimately, to agricultural failures. The frequent floods and their management challenges greatly influenced the development of governance and organizational structures in ancient civilizations.
One of the most renowned instances is the Mesopotamian flood, which influenced ancient narratives like the Epic of Gilgamesh, reminiscent of the biblical flood story. In conclusion, the Fertile Crescent's history is marked by a cyclical pattern of floods, shaping the region's agriculture and societies while leaving an indelible mark on cultural and historical narratives.