Erosion, a natural force that shapes the earth, plays a significant role in the management of trail systems. Caused by trail use, water, wind, and gravity, erosion is often most visibly apparent by the removal of soils from the trail tread or surrounding structures. Given that users and volunteers are often most focused on whats happening on the trail rather than off, this makes sense.


However, another less visible result of erosion on trails can be the unanticipated deposition of soils lower onto the trail tread or on structures nearby. These deposits can change the social or environmental sustainability of a trail, but sometimes can go unnoticed due to the slower processes involved. Fluvial Terrace might be the nearest geographic term for this process, but “flateau” describes both the shape and feeling of the outcome: boring and flat.

Keeping an eye out for these can help identify and solve some challenges that take place on trails, and also help to understand the type and amount of erosion taking place.

Saskatoon, SK: This informally created access trail cuts down a riverside embankment, showing both the visible loss of soil causing a gully (top), and a slowly forming fan below.

Flow Killers

This pattern of soil movement can change the overall shape of a trail, impacting how it feels to ride. The net result is a steep section that feels almost like a drop to flat, requiring a significant departure from trail speed. Look out for this happening on trails with sections of steep grade, high water volume, and the presence of coarse woody debris or other objects that will hold the eroded soil on the trail tread.

In some instances this tread variability is appropriate, notably on backcountry or difficult trails where tread inconsistency is a fact of life or something anticipated. However, if left unchecked or unplanned for it can result in a trail that feels jarring or inconsistent. In addition, the deposition of soils may also be significantly suffocating vegetation further down, or clogging drains and culverts.

North Vancouver, BC: A flateau (bottom) created as a result of erosion from the trail tread. Note the particularly chunky step down onto a flat surface and the beginning of a trail tread forming on the right. It’s clear that some riders don’t enjoy this feature, and that may be a result of abrupt end of flow in this section.

Assessment and Treatment

So, you’ve come across a flateau on a trail and you want to fix it. What are the options?

  1. Reshape the tread: Adjust the transition between the steep and the flat sections. Ideally use rock to armour for added durability. Manage water above the section to minimize it happening in the future.
  2. Reroute: Rebuild the trail, to reduce erosion and also restore the original trail flow.

North Vancouver, BC: One possible solution to the flow issue – a realignment allowing riders to maintain speed and preventing issues where future accumulation of soil will result in the same problem. Regardless of solution type, ensure that it fits within the character of the trail and style of building nearby.