By Harry Cooper
Erosion is the process of earthen materials being broken down into smaller particles and moved to another location. This process has helped shape the world as we know it today by moving Earth and shaping the landscape in different ways.
Is Erosion Caused By Nature Or By Humans?
The process of erosion is carried out by several different natural forces that help move these particles, such as wind, water, gravity, and ice. These agents of erosion breakdown and move earth around in different ways, creating different landforms and natural phenomenon.
But, while erosion is an important part of the natural world, human activity has caused erosion to get out of hand. Harmful agricultural practices and human development have led to erosion being much more powerful in some places, causing soil degradation, air and water pollution, and a host of environmental issues.
What is Erosion?
Erosion functions as particles of the Earth’s surface are slowly weathered away into tiny particles and transported somewhere else. This process is responsible for many different types of landforms and phenomena found in the world today.
Water erosion has helped carve out canyons and river valleys. Wind erosion is responsible for sand dunes and other desert features. Ice and glaciers helped form the massive fjords of the north. But regardless of by what means erosion occurs, the movement of earth particles has a tremendous impact on the landscape.
Agents of Erosion
Ice Erosion
Ice erosion mainly occurs when glaciers slowly move across the landscape. As glaciers move they slowly dislodge and move the rocks beneath them. While glaciers only move about a foot a day, overtime glacial erosion can have enormous impacts, carving out very distinctive landforms like fjords and valleys in their wake.
Gravity And Mass Movement
On steep landscapes soil particles can be moved downhill by gravity itself in a process called mass movement. There are several different types of mass movement processes depending on the conditions.
When slopes are less steep, mass movements occur in the form of soil creep, whereby soil moves downhill at an imperceptible rate, that can only be seen in tilted infrastructure and a wrinkly texture at the bottom of the hill. A more dramatic form of mass movement are landslides and debris flows. Landslides occur when a hill or cliffside suddenly gives way to gravity, causing the side of the slope to rapidly fall away.
Wind Erosion
Wind is a very powerful erosional agent. Wind erosion, or aeolian erosion occurs when strong winds knock soil or rock particles loose and blow it somewhere else. This types of erosion is responsible for creating landscape features such as sand dunes, ventifacts, and desert varnish.
While most desert environments around the world owe some of their most stunning features to when wind erodes rock, wind erosion can have some harmful effects. When the wind is strong enough and soil particles are loose enough, wind erosion can cause massive destructive dust storms. However, these primarily only occur in drought conditions usually caused by agricultural mismanagement.
Water Erosion
Water is arguably the most powerful agent of erosion. Not just because it is capable of dislodging and carrying so many soil particles, but because it can occur in so many different places in a variety of ways; rivers, streams, ocean waves and rain can all be agents of water erosion. Whether it occurs on coastlines, rivers, or wherever it rains, water is one of the primary ways that earthen materials get moved from one spot to the other.
Splash Erosion
One type of water erosion occurs when rain hits the earth called splash erosion. Raindrops create splash erosion by striking the ground hard enough to dislodge soil particles. If these particles are on a hill, they will very likely fall down to the bottom.
Sheet Erosion
Sheet erosion is a specific type of water erosion that occurs when rainfall intensity is greater than the soil’s ability to intake water. This causes a sheet of water to form on the soil’s surface that uniformly removes the top layers of soil as it moves.
Coastal Erosion
Coastal erosion occurs along coastlines as waves dislodge sand and rock particles to be transported out to sea by an ocean carry. While this is normally a very mild process, during storms and floods waves erode a much higher quantity of sediment which causes serious damage to coastal environments and infrastructure.
Human Impacts and Erosion
While erosion is a natural process that has been essential in shaping the natural geographic landscape, human activity, primarily from the agricultural sector, has impacted some of the major agents of erosion, causing it to become more extreme in some places. This exacerbation of erosion has had some serious environmental consequences, impacting ecosystems and environmental health across the globe.
Erosion and Agriculture
One of the biggest impacts on erosion is agriculture. When land gets set aside for commercial farming, it must be altered to suit the needs of whatever crop is being grown. When land is altered in this way it transforms from being a biodiverse natural environment to a uniform plot of land called a monoculture, dedicated to growing only one species.
This alteration causes the environment to lose its ability to regulate erosion. For instance, plant roots help keep soil compact and stable so that if an area has more plant roots soil erosion will be lower. In order to prevent erosion an area needs a large diversity of different kinds of plants. When an area of land with large trees and complex root systems is replaced with fields of cash crops that stay barren for parts of the year, erosion becomes much more likely.
On top of this, most farms till their soils annually. While this is an easy way to plant seeds and control weeds, it loosens the top layers of soil, making it much easier for soil particles to be knocked loose and eroded. When enough land is converted for agricultural use, erosion can cause some serious damage to both the environment and humans.
Impacts Of Erosion
Erosion has tremendous consequences for both the environmental and human worlds. Ironically, one of the biggest impacts is a decrease in agricultural productivity. The top layers of soil are rich in vital nutrients and some of the most important for growing healthy plants and large crop yields. When erosion strips away the top layers of soil, crop yields suffer and farmers are forced to supplement lost nutrients with chemical fertilizers, which cause pollution problems.
Chemical fertilizers used in commercial agriculture have tremendous environmental impacts. While they are only applied to agricultural soil, water erosion carries the fertilized soil into natural water bodies, where it can cause harmful algal blooms that kill off fish and other aquatic life.
This erosion can also have serious impacts on air quality as well. When wind erosion picks up enough soil particles the air becomes filled with dust which can cause asthma and other respiratory health issues. This type of wind erosion can even become so intense that it creates massive dust storms that destroy infrastructure, disrupt transport, and put human lives at risk. In fact, one of the most damaging wind erosion events was the dust bowl of the 1930s, in which over farming on the great plains led to a series of massive dust storms that leveled homes and left dust in the air for days.
Erosion And Religion
Numbers 13:20 – Is the soil rich or poor? Is it wooded or not? And take pains to bring back some of the fruit of the land – Now it happened to be the season of the first ripe grapes.
Rich Soil, As Seen in Eco Bible Volume 2
Moses asks the scouts to report on certain characteristics of the Land of Israel. On the question “is the soil rich or poor?”, Rabbi Chaim ben Moshe ibn Attar (Or HaChaim; 17th–18th century) interprets this question to mean, “Is the soil quality such that one plants one year and then must leave it to rest the second year? Or can you plant year after year without the fruits being diminished?”
Moses’ question about soil quality was deeper than we may think. Only a soil-rich Land of Israel could sustain its inhabitants. In December 2020, the Food and Agriculture Organization of the UN released its first-ever global assessment of biodiversity in the soil. As Science reported, “Soil is a mix of organic material, minerals, gases, and other components that provide the substrate for plants to grow. About 40% of all animals find food, shelter, or refuge in soil during part of their life cycle. ‘You just can’t have a Mars-like soil and expect to maintain the food supply and forests,’ warns Diana Wall, an ecologist at Colorado State University who contributed to the report.”
Today’s agronomists appreciate the importance of evaluating soil quality and learning the best ways to do it. In the words of one expert, “Soil is the basis of agricultural and of natural plant communities. Thus, the thin layer of soil covering the surface of the Earth represents the difference between survival and extinction for most land-based life.”
Studies of soil quality indicate that humans have degraded nearly 40 percent of the world’s agricultural land. This includes human-caused soil erosion, atmospheric pollution, overcultivation, overgrazing, land clearing, salinization, and desertification. A 2021 study indicates that topsoil has been eroded from roughly one-third of the Midwestern Corn Belt, stretching from Ohio to Nebraska and producing 75 percent of the corn grown in the United States. For more on soil pollution, see this post: https://interfaithsustain.com/soil-pollution/.
Ways to reduce soil degradation include reducing ploughing, recycling plant and animal manures, optimizing fertilizer use, increasing plant diversity, and rotating crops.
Soil quality significantly affects water quality. Modern agriculture has almost doubled the rate of nitrogen input to land-based ecosystems over the past 30 years. This has resulted in large increases in the transfer of nitrogen from land to the atmosphere and to rivers, estuaries, and coastal oceans. This is having “grave impacts on biodiversity, global warming, water quality and human health.”
* Featured image source
