The Ultimate Guide to Soil Erosion: Causes, Types & Effective Control Solutions

Soil erosion affects the entire built environment. This natural process weakens roads, compromises drainage systems, delays construction projects and can create safety hazards. However, these delays and complications can be prevented by developing a soil erosion plan.

To create a soil erosion plan, we must first understand what erosion is, what causes erosion and the various types of erosion. This comprehensive understanding can save you thousands of dollars and weeks of work on a project.

What Is Soil Erosion?

Soil erosion is the breakdown and movement of earthen materials. It is typically caused by wind, water, animal activity and manmade projects like roads or buildings. You can see active soil erosion in your backyard, in the middle of a desert or at the top of a mountain. It occurs at varying rates, depending on an area’s climate and topography.

Soil erosion is often equated with weathering. Though they are related, they are not identical.

Weathering vs. Soil Erosion

Weathering breaks a substance down, and soil erosion transports the broken pieces. 

Take a landslide, for example. Landslides are an extreme form of erosion, where rocks, soil and other materials rapidly descend a slope after becoming loosened or weakened. These materials are first weakened and broken apart by the weathering process.

Together, weathering and soil erosion shape the natural landscape.

Physical vs. Chemical Erosion

There are two forms of erosion: physical and chemical. Here’s how they differ.

• Physical Erosion: This form of erosion is a gradual wearing away of rock or soil particles. Physical erosion occurs when water, wind or other forces detach or break a material. This type of erosion directly affects stormwater systems.
• Chemical Erosion: A material is chemically eroded when it reacts with another material and breaks down. Oxidation is an example of chemical erosion. During this process, iron-rich rock is weakened by reactions with oxygen and water, leaving a rusty overlay on affected rocks. Another example is karst landscape that is water soluble and may lead to sinkholes.

Understanding the Different Types of Soil Erosion & What Causes Them

There are numerous types of erosion, each presenting a different challenge for human construction and transportation. Though soil erosion is typically a gradual process, it can cause catastrophic consequences if not properly managed.

Understanding the many forms of soil erosion will help you avoid severe damage to underground pipes, stormwater systems, building foundations and more.

Water Erosion

Water erosion is the transfer of soil after rain or snowmelt. Certain environmental conditions result in higher degrees of water erosion. Barren locations, like those in desert climates, often lack vegetation to absorb and slow-moving water, as well as root systems to anchor the soil. Without these natural buffers, water may continue moving freely, taking soil with it.

Areas prone to hurricanes and heavy rains also experience high degrees of water erosion. It’s important to account for your climate when assessing the potential effects of water erosion.

Types of Water Erosion

• Sheet Erosion: Raindrops can dislodge soil particles and transport them in thin layers, also known as sheets. This form of water erosion tends to remove nutrient-rich topsoil, making it a serious issue for farmers. Sheet erosion can be difficult to detect because it moves tiny soil layers rather than big chunks of soil. 
• Rill Erosion: Rill erosion occurs when concentrated water flow creates small channels in rock and soil. Rills often form on slopes and hillsides, gradually deepening and expanding if left unaddressed.
• Gully Erosion: Gully erosion is a more advanced stage of rill erosion. When water flow is strong and persistent, it carves deep channels into the soil, further widening and deepening existing rills. This process can be intensified by torrential rain or flood. In some cases, man-made drainage lines may also be eroded and expanded by gully formation, leading to increased land degradation and infrastructure damage. 
• Bank Erosion: Bank erosion is the widening and eroding of riverbanks because of excess or powerful water flow. Bank erosion can compromise man-made drainage systems, waterside properties and farming systems.

What Causes Water Erosion?

Water erosion is all about the speed and volume of water flow. Certain environmental factors can limit or increase water flow, including: 

• Rainfall Intensity: When rain falls for a long period of time or at a heavy rate, it tends to create a stronger water flow. In turn, the rate of water erosion will likely increase. 
• Soil Condition: Nutrient-rich, well-structured soil is more likely to absorb water and reduce the rate of water erosion versus dry and compacted soil.
• Slopes: Steeper slopes increase the speed of water flow,  carrying more sediment than water flowing across a flat surface. 
• Vegetation: A plant’s roots will absorb as much water as possible and help anchor the soil. As a result, areas with more vegetation will likely experience lower degrees of soil erosion compared to barren or sparsely vegetated regions.

Wind Erosion

Wind erosion is the transfer of soil particles through wind. This type of soil erosion usually occurs in climates with dry, loose soils that can easily be carried away.

Types of Wind Erosion

• Surface Creep: Surface creep is the rolling and dragging of larger particles across a soil surface. Though these large particles don’t move very far, they can dislodge smaller particles, which may be carried far distances by high winds. 
• Saltation: Saltation affects medium-sized soil particles, which may be between 0.05 mm and 0.5 mm in diameter. Wind can lift these medium-sized particles into the air, but only for so long. They usually bounce and skip across a surface rather than being suspended. 
• Suspension: Suspension affects tiny soil particles. Most of these particles remain suspended in the air for long periods, forming dust storms and tornadoes. Suspension can carry particles like sand thousands of miles away, potentially transferring soil between continents.

Gravity Erosion

Gravity pulls everything downward, including soil. When soil and rock are heavily eroded, they may lose their stability and eventually collapse. When gravity erosion occurs on a steep slope, such as a mountain, landslides and mudslides become a serious threat.

To mitigate these risks, road officials must implement effective erosion control solutions.

Abrasion and Attrition

Abrasion and attrition describe the process of loose particles wearing down and breaking apart a larger piece of rock or soil. 

For example, consider a tall rock in a desert. If a dust storm occurs, the suspended particles in this storm will batter the rock and slowly break it down. With each dust storm, this rock loses more and more of its original shape.

Uncommon Causes of Soil Erosion in BMP Areas

Without proper drainage and erosion solutions, your stormwater management plan may be disrupted by soil erosion over time. Water erosion and gravity erosion are especially dangerous to stormwater systems, but it’s important to consider some less common and more immediate threats to your equipment and practices. 

Wildlife Activity: Burrowing animals (e.g., groundhogs) and activity from large animals (e.g., deer) can disturb soil stability around stormwater features like wetland edges. Disrupted vegetation, especially with holes, weakens soil’s structural integrity and exposes it to erosion.

Heavy Equipment: Heavy equipment operating near stormwater control measures during maintenance or construction projects can compact soil or damage vegetation, reducing the soil’s ability to absorb water. Compacted soil increases runoff on the surface, leading to soil displacement and erosion.

Invasive Vegetation: Non-native or invasive plants may engulf a stormwater control measure preventing the establishment of beneficial vegetation. Invasive species often eliminate beneficial vegetation, altering the natural treatment and filtration process of stormwater.

Extreme Weather Events: Severe weather events, like hurricanes, often can exceed a stormwater control measure’s original design parameters. The intense rainfall can accelerate runoff leading to soil structure erosion.

Chemical Pollutants: Pollutants like de-icing salts, oils or excess nutrients can impact both the soil and vegetation within stormwater assets. Pollutant-degraded soil reduces infiltration and vegetation loss can increase erosion susceptibility, compromising the soil’s stability.

Improperly Functioning Features: Outlet structures like pipes or culverts may be undersized, poorly designed and/or become clogged. These issues can have cascading effects, ultimately increasing flow velocity in downstream areas, leading to erosion gullies and destabilizing slopes, banks or channels.

Erosion & Sediment Control Solutions With AQUALIS

Soil erosion, when unaccounted for, can seriously damage the built environment. This includes stormwater management systems, which are essential for government compliance and community safety.

AQUALIS ensures that your construction project, facility or property is prepared for the worst. Our stormwater management plans are equipped with top-tier erosion and sediment control solutions, helping you avoid environmental disasters and infrastructure collapses.

Protecting Your Property from Shoreline Erosion

If your property is located beside a river or lake, shoreline erosion is an especially prevalent issue. Water erosion, soil erosion, wind erosion and gravity erosion may encroach from all sides, but AQUALIS’ water engineering plans prevent these issues.

We can help you adapt, providing exceptional shoreline management and sediment reuse strategies to stay profitable, compliant and environmentally responsible. When you take steps to limit soil erosion, you create a safer future for your operations, surrounding ecosystems and local communities.

Contact AQUALIS to learn more about installing quality erosion and sediment controls for your next project.