title: Impacts of land-use and land-cover changes on rockfall propagation: Insights from the Grenoble conurbation.
abstract: Several studies have debated the incidence of global warming on the probability of rock instability, whereas the impacts of land use and land cover (LULC) changes on rockfall propagation and associated hazards have received comparably little interest. In this study we evaluate the impacts of LULC changes on rockfall hazards on the slopes above the village of Crolles (Chartreuse massif, Grenoble conurbation, French Alps) through a three-level approach: (i) diachronic landscape analysis for four different periods of the past (i.e. 1850, 1956, 1975, and 2013), (ii) computation of 3D rockfall simulations taking explicitly account of reconstructed LULC changes, and (iii) resulting changes in rockfall hazards over time. We reveal that the disappearance of viticultural landscapes (relating to the decline of cropping areas during the interwar period) and intense afforestation of the steepest upper portion of the slope resulted in a significant increase of rockfall return period associated to a gradual decrease of mean kinetic energy at the level of the urban front of Crolles. According to the Eurobloc methodology, the degree of hazard decreased significantly despite the continuous and rapid urban sprawl on the slopes. These results underline that forests can indeed have significant protection function but also call for a more systematic inclusion of LULC changes in hazard assessments in the future.
authors.affiliation: Université Grenoble Alpes, Irstea, UR EMGR, 2 rue de la Papeterie, - BP76, F-38402 St-Martin-d'Hères, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lopez-Saez
authors.affiliation: Centre National de la Recherche Scientifique (CNRS), - UMR 6042, - GEOLAB, 63057 Clermont-Ferrand cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Corona
authors.affiliation: Université Grenoble Alpes, Irstea, UR ETNA, 2 rue de la Papeterie, - BP76, F-38402 St-Martin-d'Hères, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Eckert
authors.affiliation: University of Geneva, - Institute for Environmental Sciences, Climatic Change and Climate Impacts, 66 Boulevard Carl-Vogt -CH, 1205 Geneva, Switzerland; University of Geneva, - Department of Earth Sciences, 13 rue des Maraîchers, CH, 1205 Geneva, Switzerland; University of Bern, - Institute of Geological Sciences, - CH-3012 Berne, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Stoffel
authors.affiliation: Université Grenoble Alpes, Irstea, UR EMGR, 2 rue de la Papeterie, - BP76, F-38402 St-Martin-d'Hères, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Bourrier
authors.affiliation: Université Grenoble Alpes, Irstea, UR EMGR, 2 rue de la Papeterie, - BP76, F-38402 St-Martin-d'Hères, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Berger
keywords: Land use and land cover changes; Peri-alpine conurbation; Protection forest; Rockfall modeling; Rockfall propagations