Effects of Floods

Damage from Flooding

• Flooding causes structural and environmental damage to a landscape. Floods erode soil, often on a large-scale basis. This displacement of soil leads to the weakening of structures like houses, buildings and bridges. Flood waters get into homes and buildings, causing damage to the furniture, flooring and walls within. Wood structures become weaker and may rot if the flood water stands for too long. Mold and mildew can grow in the aftermath of a flood.

Health Risks and Contamination

• In populated areas that experience flooding, the water brings with it the increased risk for diseases, infection and other injuries. Anyone caught in a flood runs the risk of drowning, no matter if the person can swim or not. Flood waters may contain sewage waste, making the water extremely unhealthy. Flood waters may contaminate drinking water supplies as well as food, leading to problems like diarrhea, according to the Centers for Disease Control and Prevention. Open wounds exposed to contaminated flood water may become infected.

Flooding and Trees

• Trees caught in flooding often are injured. Some trees have flood tolerance, allowing them to handle a certain level of flooding before injury occurs to the tree. Trees like the red maple or black willow have a higher tolerance for flooding than others. Once a tree reaches its tolerance level for flooding, the tree begins to lose oxygen and become growth restricted. Trees exposed to prolonged flooding may lose their leaves, have leaves that turn yellow or experience crown dieback. A tree standing in flood waters for too long may ultimately die thanks to the rotting or death of the root system.

Long-Term Effects

• Effects of flooding may be felt immediately or on a long-term basis. Tulane University professor Stephen A. Nelson notes that as a result of flooding, rivers may develop new channels while the old channels dry up. The sediment left behind after flooding may be hard to remove from buildings, roads and other areas. Wild animals may lose their homes due to flooding. People may lose their jobs or their homes as a result of structural damage to buildings. Additionally, insurance rates could increase.

Benefits of Flooding

• In agricultural areas, benefits of flooding may outweigh the negatives. When an agricultural area floods, the water distributes displaced sediment around the land. This sediment, rich in minerals and other nutrients, makes for more fertile soil. PBS's Nova website states that this benefit has been observed since the time of ancient Egyptians. The Egyptian farming season revolved around the annual flooding of the Nile River.