USING DINSAR INTERFEROMETRY OF RADAR SATELLITE IMAGES IN
QUANTITATIVE ASSESSMENT OF LANDSLIDE ACTIVITY IN THE GUADALFEO RIVER VALLEY
(GRANADA, SOUTH OF SPAIN)
P. Fernandez, C. Irigaray, R. El Hamdouni, J. Jimenez, J. Chacon
University of Granada, Departament of Civil Engineeering,
Granada, Spain
pazferol@ugr.es
A
SAR (DInSAR) analysis of RADAR satellite images of landslides in the Guadalfeo
River basin (South of Granada, Spain) is here presented based on ERS1 and ERS2
images following a methodology with two main steps: a first basic treatment of
SLC focused images to obtain differential interferograms with the wrapped phase
using a Digital Elevation Model (DEM) of the study zone. The second step
includes elaborations of theses interferograms with a specific DInSAR technique
to asses the average annual velocity in the landslide masses. The obtained
results are first evidences of the activity of these landslides which are
potentially affecting villages (Albuñuelas, 1100 inhabitants;
Lanjarón, 3750 inhabitants) or the Guadalfeo river with is over villages
as Vélez de Benaudalla, 2800 and Motril, 56600, which could be affected
by flash flooding after a landslide dam failure situation. Despite the interest
of assessing the risks derived from the activity of these landslides no
instrumentations were available and from these the great interest of using
DInSAR interferometry techniques may be easily understood.
The
landslide activity assessment resulting from these research shows annual
average vertical velocities for the period 1993-2000 of 6 mm/yr for Tablones
landslide, 7 mm/yr for the Lanjarón landslide and up to 13 mm/yr for the
Albuñuelas landslide.
The
quantitative assessment of landslide activity is introduced in a GIS
application to landslide hazard and risk mapping of the Guadalfeo River Valley
in which a database of landslides, along with digitized information about
element of the territory and the analysis of correlation between determinant
factors of the slope stability are combined with triggering data concerning
rainfall, earthquake activity and also landslide activity. The main outputs of
the GIS application are in terms of susceptibility, hazard and risk maps of the
region at variable scales from a pixel resolution of 10 m.