The UK’s waterways are growing in popularity. Their link with healthier living, whether through mental wellbeing or exercising along the banks, has meant that more and more people are spending time by rivers and canals. They also continue to be used for construction and industry, often transporting goods to places that are largely inaccessible by road.
However, canals and rivers are susceptible to a build-up of weeds, which can have damaging effects on the health of the water, and make navigation extremely challenging for canal boats. This guide will outline the main problems associated with weeds, and what the solutions are for those tasked with keeping our beautiful waterways clear.
The problem
Some aquatic weeds are an invasive species, and need removing to reduce spreading. This is important for several reasons:
- Large areas of weeds will reduce effective drainage
- They can cause rubbish to get stuck at key chokepoints, such as under bridges
- They can block out light that stops other, native species of weed from growing
- Weeds can smell (particularly in hot weather)
- Restrict navigational traffic trying to move through waterway as weeds get stuck around propellers
The balance between invasive species of weed and native species is currently tipped in favour of the invasives, and aquatic vegetation management helps to retain that balance.
It is important to emphasise the distinction between weeds and reed, which can often be confused. Reeds tend to be upright (5-6ft tall), and found along waterway banks, whereas weeds are a mix of floating/growing vegetation that float on the surface of the water or grow upwards from the water bed. Weeds such as duckweed tend to be much more aggressive, removing oxygen from the water which can lead to a reduction in biodiversity. This is why duckweed control is essential to maintaining healthy waterways.
How are weeds removed?
Different types of weeds grow in different ways, from floating on top of the water to form a blanket-like appearance, or growing up from the water bed. This requires a varied approach to canal maintenance, with different equipment and methods available for specific applications:
- Underwater weeds – underwater weed cutters are used to cut the strands of the weeds growing up from the water bed, which then allows it to be scooped up by weed baskets. These are then disposed either on to the bank for removal, or into hoppers (a container for loose material, which essentially acts as a floating skip).
- Floating weeds – aquatic weed cutters are used to remove floating weeds. There is a large range of aquatic cutters available – from amphibious models to boats that sit on the surface of the water. Owing to the flexibility offered by being able to attach different cutting heads and baskets, and depending on the type of weed removal, floating aquatic vegetation cutters are most commonly used along UK waterways. They are especially effective for duckweed removal.
- Reed bed maintenance – reed beds are usually created as part of a drainage scheme, or a habitat creation project. Amphibious boats are best suited to this form of waterways maintenance.
- Reeds – removing reeds requires the use of a specialist reed cutting machine. However, great care must be taken when cutting reeds, as between March and September, birds and water voles will often create nests in this habitat. While it is still important to periodically clear reeds, this should be done during the autumn/winter months, when there will be minimal disruption to wildlife.
It is important to note that aquatic weed cutters need to be delicately and carefully operated, and must therefore be operated by an experienced RYA Helmsman.
When is the best time for weed removal?
Maintenance of the canal system & inland waterways in the UK can be challenging, especially when it comes to weed removal. Waterways are at their busiest during the summer months, but this is also the time when weeds flourish.
As such, weed removal requires a careful approach, liaising with the Canal & River Trust or Environment Agency to ensure minimum disruption. The amount of time it takes to clear weeds varies drastically, and can take anything from one day to several months. For example, clearing a 2 kilometre stretch may take one week in a year, but a hot spring and early summer will make the weed growth bloom, doubling the amount of time it takes in the following year.
Further factors that affect how often canal maintenance is required include:
- Heat – This isn’t just related to air temperature, but can be affected by warm waste water entering the waterways from industry.
- Location – Nearby agricultural/commercial industry can often leech nutrients into waterways, thus stimulating greater weed growth.
It is also important to note that, while the majority of weed clearance takes place along the UK canal network, there are other bodies of water than require such work. Anywhere that weeds can flourish, such as lakes or ponds, rivers, and drainage ditches, will require some form of maintenance.
Final considerations
The historic nature of the UK’s canal system means that there are various restrictions in how machinery can be deployed. For example, weight restrictions prohibit heavy machinery from being used on towpaths, and transporting waste material from site can often prove a logistical challenge.
To ensure that maintenance is carried out effectively, it is important to engage with experts, such as The Rothen Group, who can call on a wealth of experience, with a diverse fleet that can be mobilised across the UK. Information on our weed cutting capabilities can be found on our website.
