It might be hard to believe that a raindrop can have an adverse impact on the environment. But when you combine one drop with billions and plummet them onto cultivated land, erosion is bound to take place. Although erosion is a normal and natural occurrence, climate change and greenhouse gases have altered weather patterns to produce slower-moving storms that dump rain on regions for extended periods of time. Add the effects of agriculture and development, and unprotected soil doesn’t stand much chance.
As rain falls or moves as part of a storm or the result of flooding, erosion can take many different shapes and forms. Soil erosion caused by water shows up in several types of erosion. Factors that contribute to erosion’s impact may depend on the topography of the area, whether the land is cleared or in consideration of its elevation. As water travels, it churns up the soil it passes over, carrying sediment with it and depositing it in places it wasn’t meant to be. The impact of runoff on rivers and streams, infrastructure and, yes, agriculture are sorely felt when fertile soil is washed away by the ton.
What Is Splash Erosion?
Splash erosion occurs when raindrops dislodge soil particles and move them short distances. Often considered the first part of the erosion process, dive-bombing raindrops kick up the soil structure, sometimes sending it upwards in a horizontal line that can reach heights of 1.5 meters.
As splash erosion displaces the soil it also diminishes infiltration, meaning the water can’t be absorbed into the ground and accumulates on top of the soil. This can set the stage for sheet erosion.
What Is Sheet Erosion?
During the second stage of erosion, referred to as sheet erosion, an abundance of rain bombards the soil and detaches it from its foundation. As water gathers, it skims across the surface in a sheet, rather than traveling through channels that may have been designed naturally or by man to route water runoff. This fast-moving erosion displaces the soil and carries it greater distances.
As loose particles move downhill, tons of soil particles are dislodged and moved downslope. Thick sheets of water travel and take with it a uniform layer of soil as water moves over the surface. Sediment is then accumulated, carried, and deposited.
Sheet erosion most often occurs on plowed land that has few protections from the driving forces of erosion: rain and wind. Microbursts — small but powerful bursts of air — might trigger sheet erosion when an enormous amount of rain falls at a rapid and violent rate. The force alone is enough to cause tremendous damage to the soil and surrounding areas.
Ephermeal Erosion or Concentrated Flow Erosion
The land’s topography has much to do with the impact of soil erosion caused by water. Elevated land or land consisting of slopes or hills might be even more vulnerable to the effects of erosion. As rain travels downhill, it often digs its own channels, referred to as rills. Rills struggle to control the flow while the force of water and its constant flow work to dig those channels even deeper to form gullies.
As gullies are formed from the force of water through rills, erosion becomes much harder to control and combat. The gully’s walls are overwhelmed and begin to cave in and fall to the bottom only to be carried away by moving water. As erosion travels down a slope, it eventually encounters what’s known as a “head cut”, the edge of the gully that forms a ridge. Water accumulates inside the gully to further erode the sides and bottom. The head cut is then pushed forward as water bombards it and spills over the sides and ridge to shove the head cut farther downslope. Natural bodies of water encounter this type of erosion in the form of stream bank erosion.
What Is Streambank Erosion?
Similar to gully erosion, streambank erosion also causes damage to the banks and the stream itself. Although some erosion is natural and necessary, agriculture and human-related practices invite trouble by stripping the land and removing vegetation that naturally protects the soil.
As the force of water travels downstream, and when accumulating water and the force of gravity contribute, the stream’s banks may fail as it is unable to contain and route the onslaught of water. When the banks fail, the sides collapse into the flowing water and further compromise both the stream and its surrounding areas.
Are There Solutions?
Erosion preventatives such as strip farming, terracing, and crop rotation may reduce the damage from soil erosion by working to either cover and protect the soil or attempt to route rainwater to minimize erosion and runoff. As the climate continues changing and storms become more frequent, slower moving, or more intense, combating soil erosion becomes more difficult. Although human activity plays an instrumental role in the cause and effects of soil erosion, it is also human intervention that might stop the tide.
The Journal of Soil and Water Conservation published a study on the effects of soil erosion over time. Their findings concluded that “In the case study of the Lawyers Creek Watershed (Idaho, US), the croplands exhibit much greater erosion rates and sediment yield than the non-cultivated lands. They contribute 95% of the total sediment load while accounting for only 56% of the total area. A reduction in soil erosion up to 40% can be expected when combined erosion control practices are implemented.”
Soil erosion can have devastating effects on agriculture and natural bodies of water, resulting in loss of crops and the degradation of fish and wildlife. Infrastructure such as bridges and roads might be compromised as the land that supports them is carried away. Pesticides, fertilizers, and an overabundance of nutrients disrupt nature’s delicate balance and harm the environment in myriad ways. Human interaction to combat and prevent soil erosion continues to be of high importance and practice. Now is the time to take steps to head off or reduce soil erosion — before the next storm.