Discussion

Advantages

  1. Relativity easy to calculate if data is available and processed.
  2. Integrates various factors such as rainfall, slope steepness and soil type to determine soil erosion and shows relationships between soil erosion and each factor.
  3. Reduces amount of time and money invested by the Park in trail management. Especially with identifying environmentally sensitive areas along trails. These areas can be avoided when building new trails and also preventive measures such as hardening of trails, closure of trails after snow melt etc can be applied to mitigate soil erosion and maintain trail quality in these areas. 

Limitations

  1. LS Factor: The resolution of the DEM used to calculate the LS factor is 25mx25m. This implies that the topography was smoothed out. Any small sharp incline within the 25mx25m stretch would be averaged out and the true incline would not be portrayed in the DEM. If a trail were to climb up this incline, in the real world, the LS factor for that part of the trail would be higher. Thus increasing its sensitivity to soil erosion. However, since that zone is averaged out in the low resolution DEM, the LS factor for that zone would not be as high and the results would not reflect the true soil sensitivity of that section of the trail. In order to combat this, it would be suitable to have LIDAR data for this analysis. It would also help in identifying the 1-5 m width trails along the topography and reduce the error between the traced trails and the true location of the trails.
  2. K factor: Each survey polygon in the soil map has at-most 3 types of soils present with the % availability of the soil. No information of how these different soils were distributed spatially within the polygon was given. Each Polygon was given a weighed average K factor value. The K value would vary spatially in the polygon based on the distribution of the soil. Depending on which type of soil the trail passes in the real world, the K value would be vary from the average assigned to the entire polygon. A more detailed, high resolution soil map would be preferable to make an accurate soil sensitivity map for the trails.
  3. R factor: Cypress park trails are snow capped for about half the year. Unfortunately, the R factor only accounts for erosion due to rainfall. This would be applicable for half the year however, but would not explain the relationship between snow and soil erosion on trails.
  4. Trails: The trails were traced by me. Accounting for human error, the trails on the map may be off from the true location.
  5. The effect of soil sensitivity cannot be quantified using this method. There is no indication of how walkable a moderate soil erosion sensitive trail is compared to a high soil erosion sensitive one. More research could be done on trying to quantify usability. 

Main Takeaways:

  1. High sensitivity areas are ones near river/stream beds.
  2. The results show that cypress park did a good job and designing the trail system. Most of their intricate trail system sits in low soil sensitivity areas
  3. Popularity of the trail should be taken into account when determining soil erosion sensitivity especially for areas in the moderate range. A high popularity trail would mean that even a moderate soil erosion sensitive section would show high soil erosion.