Assessing of the interaction of land-cover change on shallow landslide occurrence using an automated object-based approach

Abstract

Land-cover change could considerably lower landslide triggering rainfall thresholds allowing precipitation events with shorter recurrence intervals to initiate shallow landslides. This research focusses on developing an automated, robust and up-scalable workflow to quantitatively assess the effect land-cover change has on initiating rainfall induced shallow landslides in the Laternser Valley. Land-cover is classified using four sets of high resolution orthophotos (198x, 2001, 2006, 2009; 0.25 m spatial resolution) by applying an object-based approach with eCognition software. The correlation between land-cover change and landslide occurrence was assessed by analyzing land-cover change trends in the vicinity (< 25 meters) of mapped shallow landslides. The obtained classification accuracy ranges from 76% for 198x to 88% for 2009. The relative area undergoing land-cover change is 18% in the whole Laternser valley and 34% in the vicinity of landslides. Overall land-cover change trends indicate a shift from grassland to forest in the whole Laternser valley. However, in the vicinity of landslides the opposite is observed, namely a shift from forest to grassland and grassland to bare soil. Even though a general vegetation reduction is detected in the vicinity of landslides no correlation between LCC and landslide occurrence could be established yet.