Water Erosion Solutions: Methods, Alternatives & Innovative Products

coastline water erosion solutions

In this guide, we discuss the main water erosion solutions and control methods available in the market, including their pros and cons.

Water erosion is a natural geological process that has existed since, for lack of better words, the beginning of time. But, it has become one of the most concerning environmental issues at present, endangering the habitat of humans and other living species. Homeowners, businesses, and governments worldwide are affected by it implicitly or explicitly. 

How has it come to this? When is water erosion a threat? Is your local area or neighbourhood facing this risk at present? If so, what kind of water erosion solutions are effective at mitigating the problem? Let’s talk about it!

What Is Water Erosion?

Water erosion is one of the forms of soil erosion. It refers to the removal of soil and sediment particles from their original location by water, eventually wearing out or “eroding” the land surface. Water can easily wash away loose soil from a place due to the pressure of flowing water or rainy conditions. 

protecting australian shoreline
Protecting coastline environments from erosion is crucial

Water erosion is considered a natural phenomenon, and each soil or land type has its own rate of erosion, which isn’t threatening to the environment around it. However, human activities have accelerated the process of erosion, and have prevented the lands from recovering their quality naturally with time. 

Also, climate change, which has contributed to frequent and irregular rainfall and rise in sea level has also increased the risk of water erosion, especially in coastlines. Water erosion control methods play an essential role in mitigating the impacts of erosion.

Bluemont is a leading supplier of innovative water erosion solutions in Australia, New Zealand, and the Pacific Islands. 

Different Types of Water Erosion

Water erosion occurs in areas such as creek banks, riverbanks, lake beds, coastlines, etc. We can categorise erosion by water into different types based on how sediments are moved from their original location, which helps us map out appropriate water erosion solutions to mitigate damage. Typically, we categorise it as:

Splash Erosion

This is a direct yet less severe type of erosion caused by the impact of raindrops on the soil. It creates a ‘bombardment effect’, where the force of raindrops causes the soil particles to move in different directions. Depending on the rainfall level, the impact on the soil’s surface can be low or high, destabilising the topsoil layer. If your area is subject to frequent rainfall, the effects of splash erosion can be high.

Sheet Erosion

This type of erosion is a result of water flowing over any sloped area continuously. When the rainfall is constant and forceful, it washes away a uniform layer of soil from the surface. As the entire top layer is wiped out, sheet erosion affects soil strength and quality to a great extent. It can also make the area prone to landslides.

Rill Erosion

Rill erosion causes flowing water to carve out small valleys. When water flows rapidly – cutting deep into the soil – it can wash away soil particles and form small valleys. It is more evident in hills and bare farming fields where the soil tends to be loose. With time, the soil layer depletes and becomes thinner, affecting the quality of the land.

Gully Erosion

An extreme situation of rill erosion leads to gully erosion. This is a severe type of erosion that makes it difficult to recover the soil structure if we fail to implement adequate water erosion control methods in time. 

Flowing water creates wide channels by cutting very deep into the soil. It can even affect the water quality as large amounts of sand get mixed and washed away with water. In this case, basic erosion protection methods may not be enough.

Why Is It Important to Prevent Water Erosion?

Water erosion can pose many short-term and long-term negative consequences for the environment and the public. However, the impact depends on the severity of erosion.

Primarily, water erosion destabilises and erodes the topmost soil layer. The topsoil layer then finds it difficult to absorb and retain nutrients, losing its quality and impacting flora and fauna. It will affect the growth of crops and other plants in the surrounding area, and the marine animals in the water source will also be affected due to the mix of chemicals in the water. The disruption of the sediment structure due to soil erosion can lead to waterlogging, floods, and increased pollution.

Erosion from water can also threaten the foundation of buildings, properties, and infrastructure. For example, a bridge that runs over a river is at great risk of damage or failure if it’s prone to erosion. This was the case with Gilbert River Bridge and Kholo Creek Bridge, as their bridge pylons had fallen prey to scour. It can disrupt day-to-day activities and threaten human life.

In coastal areas, a large amount of sand getting washed away can affect the properties and landscape along the line. The devastating Wamberal Beach erosion caught the world’s eye for the sheer destruction it brought about. That’s not it. The Beadon Creek Maritime Facility also struggled to rebuild a shoreline lost to a severe storm. Coastal erosion also affects marine habitats due to the decrease in water quality.

Therefore, awareness about the effect of water erosion and mitigating it in its first stages is critical to minimising the consequences. An understanding of the best water erosion solutions is also equally important. 

What Are the Solutions to Water Erosion?

Here are the best methods to prevent erosion by water. 

Rock Bags

kyowa rock bags in shoreline to stop water erosion
Deploying rock bags to stop erosion

Rock bags are a simple yet very effective mechanism for controlling water erosion. Also known as erosion bags or rock filter units, they are simply large netted bags containing lots of small rocks. It is one of the best water erosion solutions in Australia at present. 

This innovative Japanese technology prevents water erosion and is applicable for various situations both on land and underwater. The netted bag made from 100% recyclable material is long-lasting and environmentally friendly.

How do erosion bags work?

Rock bags control wave action and currents while preventing sand from being washed away by water. The soil layer remains covered by rock bags and is therefore protected. They slow the water flow and minimise the displacement of soil. They are very versatile in application and can be used to build dams or retaining walls by placing one bag on top of the other.

Rock bags are ideal for waterway erosion control, coastal and beach erosion prevention, bridge pier scour prevention, offshore erosion control, berth protection, scour protection, and many other applications.

Advantages of rock bags

The process of filling and deploying these erosion bags is a simple task, done directly on the eroded site. It requires less manpower, and a single excavator is sufficient for average-sized products. The flexible structure is what makes them unique from other water erosion solutions. You can place them anywhere from river banks to shorelines to slopes to subsea.

The lifespan of the rock bags is 50+ years. Plus, they promote the growth of vegetation on land. They also thrive well underwater and are great for seabed erosion. The gaps between small rocks act as a safe habitat for marine life. Over time, you won’t even notice their existence. Another major benefit of erosion bags is they are a cost-efficient choice.

Rock bags are a better alternative to other water erosion solutions like rip rap because the bag holds the rocks in place. So they won’t be washed away due to water or wave pressure. They are more long-lasting.

Disadvantages of rock bags

In all honesty, we still can’t find any cons to this solution! Kudos to sustainable innovation, right?

Gabions

gabion wall for water erosion control
Gabion retaining wall – ph credit: Leonard Bentley (CC BY-SA 2.0)

Gabions, gabion baskets, or a gabion retaining wall consist of rectangular boxes of wire mesh filled with materials like small rocks, stones, or concrete pieces. The steel wire mesh of gabions is a construction of double-twisted, hexagonal wire. 

How does a gabion retaining wall work?

Gabion boxes can be placed in a row or stacked on top of each other to build a gabion retaining wall. The barrier will stabilise the soil behind and minimise the entry of water. Over time, vegetation can fill the gaps between the rocks inside the mesh baskets and strengthen the structure.

Gabions are one of the common water erosion control methods for sloping areas. Similar to erosion bags, you can also deploy them in coastal areas, lakes, river banks and bends, and other waterways to control erosion.

Advantages of gabions

As it’s a simple product of steel baskets containing rocks, gabion erosion control walls also happen to be eco-friendly. The other benefit is that gabions can be assembled and deployed on-site. They are also long-lasting, and their permeability helps drain water easily.

Disadvantages of gabions

Building a gabion erosion control wall is usually expensive and bulky work as they are difficult to install and require large equipment. Moreover, the structure of gabions doesn’t encourage habitat growth all that much. Rock bags, on the other hand, quickly adapt to the environment and support marine life and plant growth.

Riprap

riprap rock for shoreline water erosion control
Retaining wall for shoreline protection -ph by: Jonathan Wilkins (under CC BY-SA 2.0)

Riprap is one of the most permanent water erosion solutions. It refers to a layer of rocks or other similar materials of similar size or a mix of different sizes. Rocks vary in size, depending on the location and purpose. If the water pressure is high, you would need heavier and larger rocks to form a solid barrier. This is especially true for coastlines.

How does riprap work?

Similar to rock bags, you can use small riprap rocks as ground cover. Here, the rocks act as a filtering layer above the soil to hold it in place during water runoff. You can also build a riprap retaining wall or riprap seawall with large rocks to protect the ground behind the wall.

It is necessary to install a geotextile fabric layer with riprap, especially when providing ground cover for fine-grained soil. It is applicable for steep slopes, riverbanks, beaches, or shorelines for protection against wave action, tides, and high water flow. You can also use this method for bridge pier scour prevention.

Advantages of riprap retaining walls

Riprap seawalls are one of the most traditional solutions for soil erosion in coastal areas as they don’t disrupt access to the sea. As rocks and stones are readily available, building a layer of riprap is easy. It is also a simple mechanism of placing rocks strategically. Selecting sturdy rocks is important – and angular-shaped ones are more effective for this purpose.

Disadvantages of riprap

Riprap is costly in terms of both installation and maintenance. They also give a very cluttered appeal, unlike erosion bags where small rocks are held together in the bag. Without maintenance, the lifespan of a riprap seawall can be short. 

It’s also not the most sustainable practice as it doesn’t promote vegetation or support habitat growth. If you need close yet better riprap alternatives, we highly recommend rock bags.

Erosion control matting

Erosion control mats are also one of the effective ways to prevent erosion. Also known as soil retention blankets, these are open-weave structures made from biodegradable or synthetic material. Biodegradable erosion control matting usually comes in materials such as straw, coconut fibre, cotton, or jute. Synthetic options usually come in plastics, geo-fibre, or synthetic fibre.

How does erosion control matting work?

Erosion mats hold the soil in place by acting as a protective covering, preventing it from being washed away by water. They are applicable on river banks, lakeshores, beaches, hillsides, and slopes. There are both temporary and permanent water erosion control matting solutions.

Advantages of erosion control matting

The open-weave design of erosion mats allows for plant growth. Biodegradable ones also decay naturally over time, meaning they have no negative impact on the environment. However, it’s not the case with synthetic or semi-synthetic mats.

Drawbacks of erosion control matting

In this case, selecting the right type of mats and installing them correctly is essential. Otherwise, your water erosion prevention project may not be successful. Also, the lifespan of these water erosion solutions is no more than 10 years. They will have to be replaced afterwards.  Rock filter bags offer up to 50 years on land with more durability and water-resistant ability.

Disadvantages of concrete mats 

Concrete erosion control blocks can also be prone to damage or cracks and are hard to repair. You would have to replace the entire concrete revetment mat as the blocks remain connected. This is why erosion bags are the best. They are extremely durable, and even in unlikely cases of a rip, you only have to replace that particular rock bag.

Tetrapods

tetrapods water erosion control methods
Shoreline protection tetrapods

Tetrapods are concrete armour units specially engineered to control water erosion. They are a modern design of the conventional rip rap. The term tetra refers to “four,” and “pods” refer to “legs.” Originally, these were four-legged concrete erosion control blocks. However, tetrapods come in different shapes and sizes today – and can weigh anywhere between 3-40 tonnes.

How do tetrapods work?

Tetrapods are a famous coastal erosion solution – just like rock bags. 

They are mainly used to control wave action and protect coastal structures like seawalls. They are interlocked with each other to form a concrete retaining wall. Tetrapods work by allowing water to flow around them instead of against them. 

Benefits of tetrapods

The weight and interlocking design of tetrapods work effectively against extreme weather conditions, dissipating the force of the harsh waves. They are a long-lasting and durable option for water erosion control methods.

Disadvantages of tetrapods

While tetrapods are generally stable, the constant exposure to heavy winds and storms can dislodge them from their original place. They can even go into the sea and pose a threat to swimmers. These concrete erosion control blocks also tend to crack with wear and tear. Our rock bags overcome these issues as the netted bag holds the rock together. Not to forget, they also promote plant growth in coastal areas.

In addition to these, there are other water erosion solutions like geotubes for erosion control, strip cropping for slopes, and silt fences. We recommend you consult an expert to determine the best product to tackle the issue in your area. 

Wrapping Up

Now that you know how to prevent erosion, you can consider the next steps to mitigating it in your area.

Based on our evaluation, rock bags are the best and most effective product available for preventing erosion, which is why we use them for all our water erosion control projects. They adapt well in almost any terrain condition and are one of the most sustainable water erosion control methods compared to others. Plus, they are safe for the environment.

Check our specifications and brochures, and get in touch with us to learn more or order rock bags for your local project. Bluemont is a wholly-owned Australian company, providing emergency management solutions across Oceania. We have worked on a wide range of erosion control projects in collaboration with local governments and contractors. 

You can call us on +61 2 9091 0360 or email us at  info@bluemont.com.au.