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Titel |
Automatic delineation of geomorphological slope units |
VerfasserIn |
Massimiliano Alvioli, Ivan Marchesini, Federica Fiorucci, Francesca Ardizzone, Mauro Rossi, Paola Reichenbach, Fausto Guzzetti |
Konferenz |
EGU General Assembly 2014
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 16 (2014) |
Datensatznummer |
250097149
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Publikation (Nr.) |
EGU/EGU2014-12697.pdf |
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Zusammenfassung |
Slope units are portions of land surface, defined by the general requirement of maximizing
homogeneity within a single unit and heterogeneity between different units, but
whose formal characterization and practical delineation has been done in different
ways. This is often justified by the statement that the slope unit partitioning of
a territory can be used to describe a variety of landforms and processes, and for
the assessment of natural hazards. As a result, they need to be tailored according
to the specific model in use. This may result in an ambiguous definition of such
objects, while an objective definition is highly desirable, which would also allow their
reproducibility.
We have developed a publicly accessible Web Processing Service (WPS) with the aim of
incrementally achieve a satisfactory definition of slope unit. The service allows any user to
connect to a CNR-IRPI (Perugia) server, upload his own Digital Elevation Model (DEM) and
optional additional data, specify parameters constraining the size and aspect of slope units,
and quickly obtain the result in a layer in vector format. The calculation is performed using a
parallel algorithm, resulting in a processing time short enough to allow the user to tune the
input parameters, repeating the process for a sufficient number of times in order to obtain a
satisfactory result.
We use quantitative criteria to define and draw the slope units, depending on the input
parameters. The algorithm starts from a hydrologically consistent partition of the study area
into half-basins with a large number of contributing DEM cells. Each of the half-basins is
then checked against a few requirements: maximum area required by the user and maximum
standard deviation of the aspect on two orthogonal directions. Those specific half-basin that
do not meet the requirements are partitioned further, requiring a lower number of
contributing cells. The process is iterated until no half-basin exceeds the user-specified
thresholds.
Our aim is to encourage users to test the algorithm on a large number of areas with
different topographies so that new, meaningful requirements on the individual half-basins can
be defined and included in our process, in order to achieve a robust and reproducible
algorithm embodying a vast class of desiderata in the slope unit definition. This will
eventually constitute a performing and customizable tool for the investigation of a variety of
geomorphological phenomena. |
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