Flooding can kill trees, it is depend on how deeply and how long they remain submerged in the water. It can cause can cause root rot that leads to the death of the tree. It can cause poor soil aeration, that leads to poor plant growth. It can cause the soil to become more acidic. It can also lead to soil erosion and soil contamination from such man-made pollutants as oils on roadways, fertilizers in yards and farms and paints.Flooding can cause traffic problems because of some collapsing overpasses and bridges and causing traffic-light failures.Cars can float and can even be carried off by flood waters. Flood waters interrupt gas, electricity and water services and contaminates the water supply, making drinkable water unavailable. Transportation systems may go off-line because buses, trains and cabs can't travel the high water. Food from farms and markets can't be transported into flooded areas, creating food shortages. People can die in floods when their autos and homes are overtaken quickly by fast-rising flood waters. Homes, personal belongings and businesses can be damaged or lost entirely as a result of very destructive flooding. People may be unable to get to work, creating loss of income and a lack of services they would provide. It damage farmland
by burying crops in silt, uprooting crops by the force of the water or drowning crops. Flood waters can drown livestock as well. Flooding devastates wetlands and other wildlife habitats by depositing massive amounts of silt or leaving behind toxic substances such as petroleum products, fertilizers and pesticides and other man-made chemicals. This can kill animals and lead to water and land pollution. Flooding increases human exposure to dysentery and other diseases. Flooded sewage treatment plants contaminate drinking water supplies.Contaminated drinking water is a greater problem in developing countries.
Although flood is very damaging and disastrous, there are all some good effects that it may lead. Floods contribute to the health of ecologically important wetland areas. Healthy wetlands promote healthy water supplies and even affect air quality. Floods inundate wetlands with fresh waste. They also carry and deposit nutrient-rich sediments that support both plant and animal life in wetlands. Flooding also adds nutrients to lakes and streams that help support healthy fisheries. Floods distribute and deposit river sediments over large areas of land. These river sediments replenish nutrients in topsoil and make agricultural lands more fertile.
The populations of many ancient civilizations concentrated along the floodplains of rivers such as the Nile, the Tigris and the Yellow because periodic flooding resulted in fertile, productive farmland. The construction of the Aswan High Dam prevented the Nile from flooding major population centers downriver, but it also depleted once fertile agricultural lands along the banks of the river. Soil deposited by floodwater prevents erosion and helps maintain the elevation of land masses above sea level.The rapidly receding land of the Mississippi River delta is a direct result of man-made flood controls and levees that prevent topsoil-replenishing sediments from being deposited in the delta.