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Why We Close Trails: Freeze-Thaw

For those of us who love hiking, the winter can be a challenging time for outdoor conditions to lend itself to an enjoyable outing. The aftermath of a snowstorm in town may disappear in a matter of days, but on our trails, which are typically in higher elevations and under the cover of the forest above, snow can stay on the ground for much longer. Once the snow does begin to melt is when our trails are subject to the damage of the freeze-thaw cycle.

Public (Trails) Enemy Number 1: WATER

Water is the primary erosion factor for trails, especially here in Western North Carolina. If you were to go for a hike, on a hot, sunny day when the trail is completely dry, you would still be able to tell where water would go in a big rainfall, due to the ways excessive rain has rutted out and pooled on the tread surface. Sustainable trails are built with an outslope, which is an almost imperceptible slope to the downhill side of the trail. This feature immediately sheds water off the trail. This can’t always be achieved, so we use drains to get water off the trail as quickly as possible.

Snow, however, does not have the same momentum to exit the trail surface and will remain on the tread. When the soil and layer of snow/ice is frozen, it creates a durable surface that is not impacted by use. When the snow begins to thaw, it is no longer a durable surface, and the freeze-thaw cycle begins.

What is Freeze-thaw?

In the chilly morning hours of the day, there is snow/ice on the trail. As the temperatures rise throughout the day, the snow melts and is absorbed into the compacted trail surface. When the temperatures drop again, that moisture freezes. Water expands when frozen and this loosens the soil. When the temperature rises again, the ice melts and we are left with mud on the trails. This process is then repeated until the trail can dry.

When hikers use the trails when they are muddy, they alter the tread surface by leaving ruts and shoe prints. The smooth, hard packed surface that could once shed water easily has now been altered to collect water and form puddles. This has a lasting impact on our trails that take volunteers many hours to remedy.

What can YOU do?

The most important thing you can do to avoid damaging our trails is to pay attention to and abide by trail closures. Conserving Carolina keeps our website updated when we must close a trail, so check it out before you plan your hike.

If you do find yourself hiking a trail that is open but is very muddy in sections, stay on the trail and walk through the mud instead of walking around it on the outside of the trail. Walking on the edges widens the trail and can lead to a slew of other problems that can be harder to fix.

Another way you can help is to get out and volunteer. Conserving Carolina has a trail crew called the Rock Crushers that meets every Wednesday, as well as a couple additional workdays each month. Check out our events calendar to see when we are meeting this month.

Author Josh Huffstetler is serving as AmeriCorps Project Conserve Trails Associate.

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