How Water Erosion Affects the Earth

Silting

• As water erodes soil away from an area, it carries the dirt particles and deposits them sometimes hundreds of miles away. This silting process can cause major problems for humans. Dams may clog due to silt buildup, making it impossible for water to pass through the dam's water vents. Irrigation canals and other riverside structures may close and become unusable because of silt buildup. On the other hand, the silt also creates nutrient rich farmland, especially in river deltas such as the Mississippi River's terminus in Louisiana. This silt, which slowly builds up as the river flows into the sea, creates rich, valuable land for agriculture.

Rivers

• Over thousands of years, water erosion creates many important landscape features. As water flows, it carves out channels that eventually become vast rivers, such as the Mississippi, the Amazon and the Danube. These rivers host large amounts of life inside the channels cut by the water, and the constant supply of water allows many animals, including humans, to live on the riverbanks. Some rivers erode channels so deep they create spectacular canyons like the Grand Canyon, formed by the Colorado River.

Soil Erosion

• Water erodes soil from farmland, taking it away. The soil taken by the water is often the nutrient rich topsoil, leaving only less useful ground behind. Soil erosion thus poses a serious threat to farmers, who face the possibility that water may erode the very productiveness from their farms. In the developed world, farms must extensively use fertilizers in order to keep up with the loss of nutrient-rich soil. Farmers in the developing world, who have less access to artificial nutrients, instead face less productive farms if they lose their soil to water erosion.

Pollution

• Just as water erosion can take nutrient-rich soils away from one farmer and carry them to a distant location, water can also take the chemicals used to replace the lost soil. Fertilizers, pesticides and other chemical products used during farming can travel long distances in water. This water erosion thus exposes areas to pollution from sources hundreds or thousands of miles away.