Rivers have played a key role in human history: they provide food, freshwater, and fertile land for growing crops. Water can also be a destructive force of nature too. When rivers overflow, they become a natural disaster, and the effects can be catastrophic, devastating cities and fields where crops are grown. The aftermath can bring waterborne diseases, starvation, loss of land and enormous economic consequences.
On the other hand, some ecosystems thrive on seasonal floods as part of their natural ecological process. Agriculture was developed in ancient civilizations, as in Egypt, along deltas of rivers like the Nile, which depend on seasonal floods to provide deposits of sediments and nutrients, making fertile soil for farmland allowing populations to survive along these areas.
