An approach to reduce mapping errors in the production of landslide inventory maps

M Santangelo,F Bucci,F Guzzetti,F Fiorucci,M Cardinali,I Marchesini

doi:10.5194/nhess-15-2111-2015

Abstract

Abstract. Landslide inventory maps (LIMs) show where landslides have occurred in an area, and provide information useful to different types of landslide studies, including susceptibility and hazard modelling and validation, risk assessment, erosion analyses, and to evaluate relationships between landslides and geological settings. Despite recent technological advancements, visual interpretation of aerial photographs (API) remains the most common method to prepare LIMs. In this work, we present a new semi-automatic procedure that makes use of GIS technology for the digitization of landslide data obtained through API. To test the procedure, and to compare it to a consolidated landslide mapping method, we prepared two LIMs starting from the same set of landslide API data, which were digitized (a) manually adopting a consolidated visual transfer method, and (b) adopting our new semi-automatic procedure. Results indicate that the new semi-automatic procedure (a) increases the interpreter's overall efficiency by a factor of 2, (b) reduces significantly the subjectivity introduced by the visual (manual) transfer of the landslide information to the digital database, resulting in more accurate LIMs. With the new procedure, the landslide positional error decreases with increasing landslide size, following a power-law. We expect that our work will help adopt standards for transferring landslide information from the aerial photographs to a digital landslide map, contributing to the production of accurate landslide maps.

Highlights

Results indicate that the new semi-automatic procedure (a) increases the interpreter’s overall efficiency by a factor of 2, (b) reduces significantly the subjectivity introduced by the visual transfer of the landslide information to the digital database, resulting in more accurate Landslide inventory maps (LIMs)
Since the differences in the two maps lay in the method used to transfer the information from the aerial photographs (APs) to the GIS, analysis of the differences allows us to evaluate the performances of the two methods, outlining advantages and limitations
Our results suggest that geographically accurate LIMs prepared by adopting the semi-automatic procedure should be preferred to construct accurate multi-temporal or seasonal inventories

Summary

Introduction

Landslide inventory maps (LIMs) document the type and extent of mass movements in areas ranging from single slopes, or groups of slopes (Cardinali et al, 2001), to regions (e.g. Brabb and Pampeyan, 1972; Antonini et al, 1993; Duman et al, 2005), and even entire states or nations (Delaunay, 1981; Radbruch-Hall et al, 1982; Brabb et al, 1989; Cardinali et al, 1990; Reichenbach et al, 1998; Trigila et al, 2010). Aerial photographs (APs) are the only source of landslide information in the period between the 1920s and 1973, when the images captured by the first Landsat satellite became available (McDonald and Grubbs, 1975; Sauchyn and Trench, 1978)

Results

Discussion

Conclusion