Managing water and drainage is the most crucial element of sustainable trail building. The Professional TrailBuilders Association (PTBA) has put together educational videos covering these fundamentals.
The key concepts: understanding the difference between fall-line trails and contour trails, and how water behaves as it crosses a landscape. Fall-line trails channel water straight down their surface, causing erosion. Contour trails shed water naturally.
Every technique we use at NBLS — grade reversals, water bars, outslope — comes back to this one principle: get the water off the trail before it becomes a problem.