Drainage

An important and often-overlooked factor in trail construction is that of drainage. Where a trail is near the top of a hill or ridge, this is usually a minor issue, but when it is farther down it can become a very major issue. Trails, by their nature, tend to become drainage channels and eventually gullies if the drainage is not properly controlled.

A waterbar in New York’s Catskill Mountains. The trail forks right; the drainage ditch to the left.

In areas of heavy water flow along a trail, it may be necessary to create a ditch on the uphill side of the trail with drainage points across the trail. The cross-drainage may be accomplished by means of culverts, which must be cleared on a semi-annual basis, or by means of cross-channels, often created by placing logs or timbers across the trail in a downhill direction, called waterbars. Using timbers or rocks for this purpose also creates erosion barriers. Rock paving in the bottom of these channels and in the trailside ditches may help to maintain stability of these. Ideally, waterbars should be created, with or without ditching, at major points of water flow on or along the trail, and in conjunction, if possible, with existing drainage channels below the trail. Another important technique is to create drain dips, points on the trail where it falls briefly (for a metre or so) and then rises again. These provide positive drainage points that are almost never clogged by debris.