Bodo Damm

GIS-based assessment of landslide susceptibility on the base of the Weights-of-Evidence model

The major scope of the study is the assessment of landslide susceptibility of Flysch areas including the Penninic Klippen in the Vienna Forest (Lower Austria) by means of Geographical Information System (GIS)-based modelling. A statistical/probabilistic method, referred to as Weights-of-Evidence (WofE), is applied in a GIS environment in order to derive quantitative spatial information on the predisposition to landslides. While previous research in this area concentrated on local geomorphological, pedological and slope stability analyses, the present study is carried out at a regional level. The results of the modelling emphasise the relevance of clay shale zones within the Flysch formations for the occurrence of landslides. Moreover, the distribution of mass movements is closely connected to the fault system and nappe boundaries. An increased frequency of landslides is observed in the proximity to drainage lines, which can change to torrential conditions after heavy rainfall. Furthermore, landslide susceptibility is enhanced on N-W facing slopes, which are exposed to the prevailing direction of wind and rainfall. Both of the latter geofactors indirectly show the major importance of the hydrological conditions, in particular, of precipitation and surface runoff, for the occurrence of mass movements in the study area. Model performance was checked with an independent validation set of landslides, which are not used in the model. An area of 15% of the susceptibility map, classified as highly susceptible, “predicted” 40% of the landslides.

Landslide impacts in Germany: A historical and socioeconomic perspective

Landslide impacts on infrastructure and society in the Federal Republic of Germany are associated with damage costs of about US

Estimation of Direct Landslide Costs in Industrialized Countries: Challenges, Concepts, and Case Study

300 million on annual average. Despite the large overall losses due to widespread landslide activity, there is a lack of historical impact assessments, not just for Germany’s low mountain areas but those of entire Central Europe as well. This paper is a collection of three case studies from Germany that seek a better understanding of landslide impacts and their economic relevance at local and regional level. The first case study investigates damage types and mitigation measures at a representative landslide site in ways that support to gain insight into historical hazard interactions with land use practices. This case history is followed by a case study dealing with fiscal cost impacts of landslide damages for an example city and the highway system of the Lower Saxon Uplands, NW Germany. In addition to a cost-burden analysis for affected public budgets, an overview of the principles of disaster financing in landslide practice is given. The third case study is focused on the conflicts of urban development in hazard areas, with an economic approach to balancing safety and public welfare interests. Each case study is based on historical data sets extracted from Germany’s national landslide database. This paper presents three different case studies that in combination are a first step towards assessing landslide impacts in integrated perspective.

Landslide Database for the Federal Republic of Germany: A Tool for Analysis of Mass Movement Processes

This paper presents a short summary of the challenges and concepts in previous landslide loss studies and introduces a methodological framework for the estimation of direct landslide costs in industrialized countries. A case study of landslide losses for federal roads in the Lower Saxon Uplands (NW Germany) exemplifies the application of this methodology in a regional setting.

Slope Stability and Slope Formation in the Flysch Zone of the Vienna Forest (Austria)

This contribution deals with an initiative to develop a national landslide database for the Federal Republic of Germany. The paper highlights the structure and contents of this database and outlines its system architecture that underlies the current database transformation. With this background, the paper examines the database potential for research on landslide disaster impacts and hazard mitigation.

Klebelsberg revisited: did primary succession of plants in glacier forelands a century ago differ from today?

The Rhenodanubian Flysch of the northern Vienna Forest is composed of various layers of sandstones, marly shales, calcareous marls, and clay shists, which are covered by Quaternary periglacial cover beds and loess deposits. This area at the margin of the eastern Alps represents an undulating landscape of the Austrian low-mountain regions. The Vienna Forest Flysch region is considered to be susceptible to landslides. Both petrography of the bedrock and soil mechanical properties of the Quaternary sediments control the current slope dynamics in the study area. In a temporal context it is evident that the stability of slopes exceeding is controlled by a succession of several steps of slope formation. On the basis of field surveys, laboratory analyses, and slope stability modelling, results from investigations on recent landslides demonstrate five different phases of slope formation. In general, after passing these phases the stability of studied slopes is increased, due to the different soil mechanical properties of the potential sliding masses.

A landslide inventory system as a base for automated process and risk analyses

Since the Little Ice Age maximum in mid-nineteenth century, glaciers of the Alps lost more than half of their respective area. The chance to observe primary succession in deglaciated areas has motivated researchers ever since with quite a number of studies on vegetation dynamics in glacier forelands dating back to the nineteenth and early twentieth century. Harsh site conditions make glacier forelands challenging environments for the colonization. Due to high mortality rates during establishment, plant colonization and vegetation dynamics in glacier forelands are commonly considered slow and delayed. Recent research, however, shows that primary succession of plants in glacier forelands is accelerated, most likely due to climate warming. This is demonstrated by a speedup of the colonization process itself as well as by changed colonization strategies of the plant species involved. Employing a virtually complete species list for 1911 provided by Raimund v. Klebelsberg and our data collected along a chronosequence roughly a century later, we compare the floristic composition and structural attributes of the plant species governing primary succession within the glacier foreland of Lenksteinferner (ferner is a Tyrolean toponym for glacier) (South Tyrol, Italy). We address questions of changes in the dynamics of colonization, the plant species involved and their respective biological traits. Our study confirms that present-day vegetation dynamics in the glacier foreland are accelerated, colonization occurs faster and more species are involved in early colonization than a century ago. However, the dominant early colonizers are essentially the same and there are no fundamental differences concerning the spectra of biological traits between the two sampling dates. Altered colonization strategies due to climate change could not be detected within the glacier foreland of the Lenksteinferner, probably due to a compensation of climate warming during the twentieth century by the shift of the glacier terminus to a higher elevation. As the difference in temperature between the two sampling areas matches the magnitude of warming between the two sampling dates, similar temperature conditions in front of the glacier terminus today and at Klebelsberg’s times can be assumed.

Landslide Susceptibility Modeling on Regional Scales: The Case of Lower Saxony, NW Germany

Landslide research requires consistent and widespread data. Many countries within the European Union have national landslide inventories to fulfill these demands for their respective research. However, those inventories were usually not intended to provide the technical basis for automated process and risk analyses during their design phase. The ongoing development of Germany’s national landslide database offers the opportunity to do this differently. This paper introduces a landslide inventory system called WISL suitable for data handling as well as for novel automated process and risk analyses on a national scale. WISL is designated to form the technical infrastructure for a German national database. Its core consists of an open source relational database management system (PostgreSQL), standardized input and registration methods as well as integrated analyses modules, which avoid large data movement and allow for rapid risk analyses. We present proof-of-concept results of endangered infrastructure related to automated risk mappings based on topography and proximity of active landslides. The use of open source software and the application of a standardized input and data acquisition system for experts, coupled with custom analysis modules, constitutes a step toward automated risk maps by a mere ‘button-press’. Future developments for the inventory lie in the field of refining and inventing analysis modules and collecting data, for which WISL provides a firm technical base.

Case Histories for the Investigation of Landslide Repair and Mitigation Measures in NW GermanyOpen image in new window

This paper presents a regional landslide susceptibility model for the Federal State of Lower Saxony, NW Germany. A modified Information Value approach has been developed, which uses bivariate statistics to identify the spatial probability of landslide occurrence. To optimize the approach for regional applications, several modifications have been made: landslide pixel mapping is replaced by point representation and the weighting function uses landslide densities based on attribute areal coverage. The input data of the landslide susceptibility model include a spatial inventory of about 900 landslides and different data sets of geomorphometry, lithology, and land use.

Historical soil erosion by water in Germany: Scales and archives, chronology, research perspectives

To understand the complex interactions between landslide risk, public and private risk awareness, including land use practices and repair and mitigation measures in a complete manner, case histories were developed and analyzed using the example of the highway network of the Lower Saxon Uplands, NW Germany. The case histories utilize datasets extracted from the German landslide database that includes information of historical and current landslide impacts, elements at risk as well as land use practices and provide an overview of spatio-temporal changes in the exposure and vulnerability to landslide hazards over the past 250 years. For the developed case histories the recorded landslide events were categorized and classified at representative sites, according to landslide types, processes, and damages as well as applied repair and mitigation measures. In a further step, data of recent landslides are compared with historical and modern mitigation measures and are correlated with concepts of risk management. As a result, it is possible to identify some complex interactions between landslide hazard, hazard awareness and damage impact. The case histories show that especially since the last 20 years public risk awareness rose due to an apparent increase in landslide frequency and magnitude at some sites. Before the 1990s landslide mitigation measures were mainly low cost prevention measures such as the removal of loose rock and vegetation, rock blasting, catch barriers, and temporal or perpetual traffic lane closure. Recently there is a shift towards the implementation of expensive mitigation measures in order to minimize landslide occurrence. Local decision makers increasingly invest in expensive long-term stabilization projects like soil anchoring, rock nailing, and steel-reinforced concrete walls.