Flood is usually an overflow of an expanse of water that submerges land and the inflow of tide onto land. Floods are the most frequent and costly natural hazards, causing almost 90 percent of all the damage related to natural disasters. Floods usually cause large-scale loss of human life and wide spread damage to properties. This damage is known as flood damage. Unimaginable damage will be caused to agriculture, thereby affecting the United State's planning and this will upset its financial budgeting, thereby slowing down the economy as a whole.

The effects of flood damage can be categorized into three types, namely, primary, secondary and tertiary. The primary effects of flood damage include physical damages like damage to bridges, cars, buildings, sewer systems, roadways, and even casualties like people and livestock death due to drowning. The primary effect of floods is due to direct contact with the flood waters. The velocity of water tends to be high in floods and consequently, discharge increases as velocity increases. Because of excess rainfall, the rivers and streams flow with higher velocities wherein they are able to transport larger particles like rocks as suspended load. Such large particles include not only rocks and sediment but during a flood it could also include large objects such as automobiles, houses and bridges. Massive amounts of erosion during the floods can undermine bridge structures, levees, and buildings causing their collapse.

During floods, water will also enter human built structures causing water damage. The flood damage to houses include ruining of furniture, damage to the floors and walls of the house and damage to any other item that comes in contact with the water. Automobiles on the roads get stranded in the floods and they get carried away by the flood waters or water enters into the automobile, which results in damage that cannot be easily repaired. The flood water carries sediment as suspended load. As the flood waters recede, the sediments get deposited and things and structures including the interior of buildings usually get covered with a thick layer of stream-deposited mud. Farmlands affected by floods face a huge loss as they usually result in crop loss. Livestock, pets, and other animals are often carried away by the strong currents of the flood water. Humans who get caught in the high velocity flood waters often get drowned.

Among the secondary effects of flood damage are the disruption of many essential services like gas and electricity. Flood damage also includes the contamination of the drinking water supply, if sewage treatment plants are flooded. This poses a greater threat because this may result in disease and other health hazards, especially in under developed countries. The public transportation systems may also be disrupted during floods, resulting in shortages of food and other supplies.

Tertiary effects of flood damage are generally long-term effects like the location of river channels that may change because of flooding; fewer new channels will develop, leaving the old channels dry. Farmlands with crops get destroyed by the sediment deposition caused by the floods. People may not be able to make it to their workplace due to disruption of services. The floods may also result in destruction of wildlife habitat.

Although floods have some advantages, if we look at it in a broader perspective we can conclude that largely, floods cause havoc to life and property of mankind. By following various preventive measures the effects of flood damage can be reduced to a great extent.