Final answer:
Flooding can occur when the water level in a stream exceeds its banks, leading to overflow. Various factors such as topography, climate, rainfall patterns, and human activities can contribute to the occurrence of floods.
Step-by-step explanation:
Flooding can occur under various conditions. It can happen when the water level in a stream exceeds its banks, leading to overflow. Floods can also be caused by heavy rainfalls or when rivers experience extreme water levels. Factors such as topography, climate, rainfall patterns, and human activities can contribute to the occurrence of floods. For example, low-lying areas, areas near water bodies, and regions with poor drainage systems are more prone to flooding.