Monitoring of Unstable Slopes in the Italian Alps Using Satellite Radar - Results of the ESA/ESRIN DUP Alpslope Project
Klaus Belitz(1) and Johannes Zilger(1)
Teledata GeoConsult GmbH-srl,
Natural Hazards, Landslides, Monitoring, ERS, Envisat, Synthetic
Aperture Radar, Differential Interferometry
While unstable slopes in the Alps are a severe permanent threat for the
human society and economy in the region, the mapping and analysis of the
geologic risks in this area is of essential importance and a strong
The complete urban and regional planning has to be based on an analysis
and classification of the terrain in terms of risks, to prevent existing
buildings and infrastructures from damage or loss. In areas of elevated
geo-risks additional preventive measures have to be planned and realised.
As short-term activity the safety of inhabitants and visitors has to be
guaranteed by recognising potentially hazardous sudden events to
initiate security measures timely in advance (closing of roads,
evacuation of buildings) supported by appropriate monitoring systems.
The ‘Alpslope’ Project: Partners, Elements and Goals
Main objective of the presented project ‘Alpslope’ within the framework
of ESA funded DUP (Data User Programme) is to develop and demonstrate
services for mapping and monitoring unstable slopes based on widest use
of satellite remote sensing data and integration in Geographical
Information Systems (GIS) in close co-operation with a selected
key-user. The results in terms of feasibility of the service and its
performance regarding accuracy, speed of delivery and costs and benefits
of the service are analysed and presented in detail.
The key user committed to the project is the Geologic Service
(Geologischer Dienst, Servizio Geologico) of the Autonomous Province of
South Tyrol, being the authority responsible for all geologic mapping
tasks regarding geology, tectonics, and associated geo-risks.
As an intermediate user, the Department of Earth Sciences of the
University of Modena and Reggio Emilia is involved in the project.
Expert know-how and extended experience in mapping of hydro-geological
and geomorphologic hazards and risk assessment is provided.
The Methods: Earth Observation and Ground Based Techniques
The main methodological element is the detailed detection and mapping of
the spatial distribution of the unstable slopes induced hazards. Direct
information on geometric surface changes and displacements is provided
by Differential SAR Interferometric Processing (DInSAR) of ERS and
In the terrestrial methods used so far permanent punctual measurements
of the geometric surface changes via Differential GPS, laser theodolites
and borehole instrumentation are carried out. The system presented in
this paper and initiated by the project is capable to integrate ground
measurements and spatially extending observations derived from remote
The project is developed within two test-sites, Corvara and Nals in the
Autonomous Province of South Tyrol in the Italian Alps, defined together
with the key user.
According observations of the Geologic Service, surface displacements up
to 11 m in the period between spring and autumn already occurred with
the Corvara landslide.
The test-site near the village of Nals / Nalles in the Etsch-valley,
lies half way between Meran and Bozen on the southern mountain slopes of
the valley. The test-site is part of a long colluvial slope, extending
below a steep wall of outcropping rocks from Meran-Marling /
Merano-Marlengo in the Northwest to Eppan / Appiano near Bozen in the
Southeast. A series of landslides and debris flow events has actually
occurred since the year 2000, and implementation of appropriate measures
is a pressing issue.
Results of the two test-sites are presented and discussed in the paper.
The presented project ‘Alpslope’ displays the status of development of
earth observation techniques suited for addressing the issue of unstable
slopes and emphasises on interacting with the involved key users and
intermediate users, meeting their specific requirements and finally
integrating developed mapping products and monitoring services in the
users operational environment.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,