Nature-based solutions for water management on trails

Graham Calder from P3 Permaculture showing volunteers from Sentiers Wakefield Trails how to measure the slope with the water level.

With a maintenance grant from Trans Canada Trail, we hired local ecological designer, Graham Calder of P3 Permaculture, to lead a work bee with volunteers. The purpose of the hands-on workshop was to implement nature-based solutions for managing water on trails. The goal was to prevent erosion of natural features such as streams and banks while reducing damage on the trails themselves. We learned a number of techniques using natural materials - mostly different sized rocks - to slow and divert water.

Two of these techniques are described below the photo gallery.

Berms, Rolling Dips, and outcropping

We constructed multiple berms (raised barriers) and rolling dips (depressed troughs) across the trail to direct the flow of water into the forest around the trail. 

First, we had to figure out where to put them. We observed where the water was going now and the impact it was having. For example, in one place the water was falling off a switch-back trail like a mini-waterfall. Where it was hitting the forest floor, it had caused a hole beside a tree, damaging its roots. With the roots unable to hold the tree in place, it had fallen over and hit another tree. Not good.

In other places, it was running under logs that had been placed to mark the trail, which were now decomposing. Mostly, it was running straight down the trail tread causing further erosion. The water was washing the material comprising the trail (mostly 3/4 crushed stone) into the forest beside the trail. 

Next, we used a water level to mark where the berm would go, and placed flags. This ensures the mound is high enough to catch the water, and that the outcropping is lower so the water flows away rather than pools in one spot. 

Finally, we hauled 3/4 crushed stone and shaped it into the mounds where the flags marked the spot. Rather than trusting our visual perception solely, we re-tested with the water level before moving on to the next berm. In total, we installed 8 berms that day. 

Three rolling dips had been put in place last fall. Graham gave us some feedback on how we could improve these, and also showed us the evidence that they were helping to divert the water from the trail.

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It's hard work, but it's fun!

Building berms on the section of Trans Canada Trail between Mill Road and Centre Wakefield La Pêche.

Finished berm. We built a lot of these and will likely do more!

Rock bowls, sieves and armouring

Another technique we learned and implemented at the workshop was using larger rocks to slow water in the places receiving the water we were redirecting. Graham showed us how to check for active and passive erosion, which confirmed the need to slow and spread the water as it moved downhill to the municipal ditch.

We built three water treatments in a gully where snow melts and flows in large volumes in the spring - a "zuni" or rock bowl, a series of one rock sieves, and rock armouring. These are shown in the pictures below. One key takeaway of the workshop was that multiple smaller interventions are more effective than one large project when it comes to managing water to prevent erosion. 

While we were pretty impressed with the amount of work we were able to achieve as a small group of volunteers, we are not done yet! We will continue to implement what we learned on other parts of the trail network.

Before - materials brought onto the trail to slow and spread the water that was causing erosion beside the trails

After - a "zuni" or rock bowl serves to slow the water before it continues on down the hill to the municipal ditch.

A series of one rock sieves aka one rock dams continues to slow the water as it travels downhill in the gully.

Brad and John admire the rock armouring that will protect the bank from erosion when water moves through the gully from melting snow or heavy rains.