When the water level of a stream or river exceeds its natural banks, it has reached its

When the water level of a stream or river exceeds its natural banks, it has reached its flood stage. This is a real panic stage for people living nearby the rivers and streams that has overflowed its natural banks. This flood situation can destroy any city or village and also drastically impact the financial situation of the area. Most cities and states move their citizens away from the river banks before it reaches this danger stage. Before the emergence of technological advancement, historical evidence proves that many great cities were destroyed due to such situations. 

Answerseasonal dry and wet winds this answer is right outta of the book