Water Erosion Solutions: Methods, Alternatives & Innovative Products

coastline water erosion solutions

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

Water erosion is a concerning issue faced by homeowners, businesses, and governments worldwide. It is even a bit ironic that the water that nourishes our earth can also be detrimental in some ways. If your local area or neighbourhood faces this risk, you would want to stop water erosion in the best possible way. 

What Is Water Erosion?

Water erosion is, basically, the removal of soil and sediment particles from their original location, 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. 

Although water erosion is a natural phenomenon, human activities have aggravated it over time. 

Factors like climate change – which cause irregular weather patterns – tend to increase water erosion, especially in coastlines. Water erosion control methods play an essential role in mitigating the impacts of erosion.

protecting australian shoreline
Protecting coastline environments from erosion is crucial

What Are the Types of Water Erosion?

Water erosion occurs in areas such as creek banks, riverbanks, coastlines, etc. We can categorise its 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 raindrop splash. It creates a ‘bombardment’, 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.

Sheet Erosion

This type of erosion usually happens on slopes, although it can happen anywhere. 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.

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 farming fields where the soil tends to be loose.

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 Water Erosion Prevention Important?

Water erosion can pose many negative consequences for the environment and the public.

Basically, 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. 

Your crops and other plants won’t grow healthy and marine animals in the water source will be affected by chemicals mixing in the water.

Water erosion 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 eyes 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.

As you can see, it is important to control water erosion as best as we can. 

What Are the Solutions to Water Erosion?

Kyowa Rock Bags

If you are looking for the best way to stop water erosion, here’s the solution. Kyowa rock bags, aka erosion bags or rock filter units, are simply large netted bags containing lots of small rocks. 

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.

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

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 therefore protected. They slow the water flow and minimise the displacement of soil. You can also use rock bags 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, offshore platforms,  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.

Rock bags have a lifespan of up to 50 years and promote the growth of vegetation on land. Underwater, 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.

Disadvantages of rock bags

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

Gabions

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. Gabions are popular water erosion control methods.

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

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 a common soil erosion prevention product for sloping areas. Similar to erosion bags, you can also deploy them in coastal areas, lakes, river banks and bends, and other waterways.

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, gabions don’t encourage habitat growth all that much. Kyowa rock bags, on the other hand, quickly adapt to the environment and support marine life and plant growth.

Erosion Control Matting

Erosion control mats or soil retention blankets 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 protecting covering, preventing it from being washed away by water. They are applicable in river banks, lakeshores, beaches, hillsides, and slopes. There are both temporary and permanent water erosion control matting solutions.

Advantages of erosion control matting

The benefit of erosion mats is that the open-weave design 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. Kyowa rocks offer up to 50 years on land with more durability and water-resistant ability.

Riprap

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.

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

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 water erosion control methods for 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 one of the expensive water erosion control methods in terms of both installation and maintenance. They 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 Kyowa rock bags.

Revetment Wall

Revetment walls are sloping structures built to protect banks of waterways and shorelines from water erosion. They are available in gravel, rock, concrete, or a combination of materials.

How does a revetment wall work?

A revetment wall slows the flow of water, lowering its impact on soil movement. It is usually permeable to allow water to drain and minimise hydrostatic pressure. Revetment walls only control water force and do not necessarily eliminate sediment loss. In contrast, rock bags do both tasks efficiently. They are water erosion solutions for protecting coastal areas from wave action, storm surges, and tides similar to erosion bags. 

Advantages of a revetment wall

It is a durable method for coastal and beach erosion. A revetment wall does a good job of absorbing the energy of harsh waves compared to riprap seawalls. Also, the gaps in revetment walls allow marine life residing near the shores to move in and out of the ocean.

Disadvantages of revetment walls

Unlike rock bags, the construction of revetments is not cost-effective and requires maintenance. As they also remain a barrier to natural coastal dynamics, you may notice increased sediment loss in unprotected areas. It will also hinder access to the beach.

Concrete Erosion Control Mats

A concrete mat or concrete revetment mattress is a blanket-like structure consisting of concrete erosion control blocks interwoven together on a sturdy geotextile material. It is one of the permanent water erosion solutions used to stabilise land areas with loose soil. Concrete mats for erosion control come in different sizes and are ideal for protecting slopes up to 60⁰.

How do concrete erosion control mats work?

When placed over a land area susceptible to erosion, concrete revetment mats act as a shield to protect the soil from water runoff. Like Kyowa rock bags, they hold the soil in place. 

These mats protect river and waterway banks, shorelines, beaches, culverts, pipes, bridges, and boat ramps. Maritime authorities also use them for berth protection and scour prevention.

Selecting the right erosion control concrete mat for your purpose requires expert assistance. You have to pay attention to the block type, filter layer, soil type and conditions, nature of the land, etc.

Benefits of concrete mats

The mats come packaged as rolls and are fairly easy to install at the site. They are also an environmentally-friendly and sturdy choice. The gap between concrete erosion control blocks allows for vegetation growth. It also allows water to permeate the revetment mattress, keeping the soil fertile.

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 are concrete armour units designed to control water erosion. 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.

tetrapods water erosion control methods
Tetrapods for shoreline protection

How do tetrapods work?

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

They 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 water well. They are a long-lasting and durable option for water erosion control methods.

Disadvantages of tetrapods

Constant exposure to heavy winds and storms can dislodge tetrapods 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. Kyowa rock bags overcome these issues as the netted bag holds the rock together. 

In addition to these, there are other water erosion solutions like geotubes for erosion control, strip cropping for slopes, and silt fences. 

Wrapping Up

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

Check Kyowa’s specifications and brochures, and get in touch with us to learn more or order rock bags for your local project. We are a wholly-owned Australian company, providing emergency management solutions across Oceania.

You can call us on +61 2 9091 0360 or email us at  [email protected]

Check out these success stories of the Kyowa rock bags: