Erosion, in simple terms, is the process by which surface action of wind or water remove dissolved material, rock and soil from one location to another. Typically, wind and water erosion occur on sand, rocks, hilly regions, deserts and along water flow areas. Physical or Mechanical Erosion is said to take place when rock or soil undergo particulate breakdown; on the other hand, when rock or soil are dissolved into a solvent, usually by water, and a flow-away of the solution happens, this is known as Chemical Erosion. In each case, the sediment caused by erosion can travel for thousands of kilometers or just a few centimeters.
Water damage or water erosion happens when flowing water carries with it pieces of dirt, rock and sand. The four major types of water erosion are:
• Sheet erosion – occurs when rainfall and runoff water move loose soil
• Rill erosion – is concentrated in a small area in a landscape and over time becomes a well-defined channel called a rill
• Gully erosion – is the extended form of rill erosion where a rill expands to cause a huge rift in the land
• Bank erosion – is caused by natural flow of water in rivers and streams
These types of erosion are particular to the kind of land that is impacted by water and are the reason for the existence of canyons, cliffs, shorelines and valleys.
Flowing water causes erosion of land by sheer velocity of the water. As rivers and streams flow, they erode soil and carry the sediment far from their original location; the hydraulic action of the flowing water carries small, fast-moving sediment particles downstream slowly chipping at bedrock along the way and causing more erosion.
Along coastlines, waves cause erosion as they are a source of powerful movement and can move debris and sand up and down shorelines during high tides, hurricanes, tropical storms etc. However, according to a study by the University of Oklahoma, erosion caused by waves is actually small as even though they seem impressive the water movement is actually small in comparison and the sand moves in a cyclical pattern. Waves can actually add quantities to amounts of beach sand.
Over the years, human intervention with the environment has increased by nearly 40 times the rate of water erosion; in the US alone nearly 4 billion tones of soil is eroded each year by movement of water. Where jetties, seawalls and other structures are put in place to keep the sea from moving closer to shore, they actually cause the water to head back into the sea with more velocity than normal thereby causing the beach to lose more sand.
Together, wind and water erosion account for nearly 85% of degraded land globally making it a significant environmental problem world-wide.
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