Pertanyaan

The following text is for questions 1 to 4. Flood is an overflow of water that soaks or covers land. Floods are the most frequent type of natural disaster worldwide. It can be caused by several things, naturally and form the effect of human behavior. The most common cause is because of the over capacity of the body of water, e.g. river or lake. As a result some of the water flows outside of the body of water. It can also occur in rivers, when the strength of the river is so high that it flows right out of the river channel. A flood from sea may be caused by a heavy storm, a high tide, a tsunami, or a combination the three. Soil and vegetation absorbs most of the surface water, floods happen when there are lack of trees and the soil alone cannot absorb all the water. The water then runs off the land in quantities that cannot be carried in stream channels or kept in natural ponds or man-made reservoirs. A flood can also be caused by blocked sewage pipes and waterways, such as the Jakarta flood. There are several types of flood. Periodic floods occur naturally on many rivers, forming an area known as the flood plain. These river floods usually result from heavy rain, sometimes combined with melting snow, which causes the rivers to overflow their banks. A flood that rises and falls rapidly with little or no advance warning is called a flash flood. What is the cause of periodic floods?