Geography Reference
In-Depth Information
layers, the different elements of the geographic representation can be ana-
lyzed based on geometric overlaps. Because of the three-dimensional nature
of landslides, the cartographic representation supports the use of multiple
viewpoints and user-defined visualizations of cut-lines that help users to
understand and examine the geological structure. The analyses and visual-
izations need to be very accurate to meet the goals of users and established
conventions of geohazard analysis.
The municipality of Isla Vista, California, near Santa Barbara, has a very
high population of students. Apartments overlooking the Pacific Ocean are
in high demand, but ongoing erosion has led to several apartments being
condemned. Students from the University of California, Santa Barbara, were
involved in creating a GIS that mapped details of the cliff edge and the cliff
base that could be used in the county GIS. Existing data from the county GIS
was first analyzed and then students went out to collect additional data using
GPS and video cameras. To assure that the data was accurate, the cliff data
on erosion activity, storm drains, vegetation, and beach access points was
collected four times. Using county data, students also analyzed the rate of
coastal erosion since 1972. The changes, on average just less than 1 foot of
cliff erosion per year, were used to make a prediction of the coastal cliff
changes through 2055. The cartographic representations included maps, ani-
mations, and interviews. The high accuracy of the data points to the impor-
tance of having robust scientific data to fulfill conventions for data that will
be used by the municipality and county in making decisions.
Section of map produced with a
GIS-based analysis of landslide hazards on Puget
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