Exercise 8
Map Workshop
Post-exercise Assignment
Jong Park
GSI: Kristen Podolak
1.
In the assigned overlay analysis, I examined the relationship between the slope of the landscape
and the frequency of landslides. My hypothesis was that there is a positive correlation between slope and
landslides. My analysis indicated that there were 6 slides occurred in percent-slope category 0-8%. 37.5%
of all slides occurred in this category, and approximately 10% of the total area of the canyon was
comprised by this category. By dividing the percent of slides occurred by the area comprised by this
category, we could get a ratio of 3.75, which explained how much of the landslide was caused by the 0-
8% slope. In 8-15% slope category, 2 slides, which was 12.5% of all slides occurred took place, 10% of
the canyon was comprised by this category, so the ratio was 2.5. In 15-25% slope category, 11 slides,
which was 68.8% of slides occurred took place, 5% of the canyon was comprised by this category, so the
ratio was 4.6. In >25% slope category, 16 slides, which is 100% of all slides occurred took place, 70% of
the canyon was comprised by this category, so the ratio was 1.4. Relative to the areas the percent slope
categories comprise, this was the order of least slide-occurring to most slide-occurring categories: >25%,
8-15%, 0-8%, and 15-25%. The result does not support my hypothesis. The reason that slope and slides
are not positively correlated is because, in >25% category, the land is too steep to accumulate sediments
that will cause the landslides. The reason for the high ratio of 0-8% category may be that the slides
already occurred in the area caused the slope to go down. All in all, the intermediate to high 15-25% slope