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Investigations in Slope Development through Landslide Activity - Concepts, Methods, and Implications for Interdisciplinary and Interoperable Data Management

SCHMIDT, Jochen (jochen.schmidt@uni-bonn.de), GAERTNER, Holger and DIKAU, Richard, University of Bonn, Department of Geography, Meckenheimer Allee 166, D-53115 Bonn, Germany

Key Words: landslide investigation, slope stability, landform evolution, data integration

It is an open research question, to which extent landslide activity contributes to landform evolution, especially under moderate humid climatic conditions? In a multidisciplinary research project at the University of Bonn, we are trying to get insight into the process of slope development through mass movements. Research methods include local field investigation and stability analysis, mapping and modelling of landslide susceptibility, geophysical subsurface monitoring, and geomorphometric slope profile analysis. The research aim of the coupled use of these different techniques is to model quantitative measures for sediment transport through landslides on hillslopes in the Bonn area. In this paper, the research approach, methods, and a few first results are presented. Special emphasis is given to the data management. The scheme and system used to store and manage the data and analysis results is discussed. Additionally, an alternative, object-oriented approach is presented.

In quantifying the sediment transport through mass movements over longer time scales, we have to cope with several problems, e.g., (1) unknown boundary conditions in time, (2) discontinuity of the process, (3) different process types, and (4) coupling with other (slope) processes; therefore, a statistical approach, coupled with slope stability analysis is used to estimate the contribution of landslides to slope evolution under variable (i) climatic, (ii) morphometric, and (iii) geologic boundary conditions. First, several indices describing mass movements over longer time scales were identified and selected for the study. Slope profile types are extracted for the study area using several morphometric algorithms. Material properties from laboratory tests are related to geologic units. Several slope stability models based on different approaches are used to model the selected landslide indices under different morphometric and geologic conditions. The models are calibrated using data from several landslides in the Bonn area. Results show the dependency of landslide occurrence in the Bonn area on hillslope morphometry and geology. These findings are used in a sensitivity study on the influence of different climatic conditions, which shall lead to an estimation of spatio-temporal landslide activity. Investigations on sites near Bonn are carried out, producing a large amount of field and laboratory data. Supplementary information is available by climate data, geologic maps, topographic maps, DEMs, etc. Additionally, data resulting from interpretation, analysis, and modelling of the field data must be handled.

In our project, storage, visualization, and analysis of these data is realized using GIS (Arc/Info, GRASS), geotechnical software (GeoDIN), databases (Access, Oracle), slope stability programs, and several other software products. This shows that landslide investigation is a typical example for the heterogeneity of data and methods used in Geosciences, which necessitates a careful and consistent data management. Presently, a relational data model and diverse structures, methods, and tools to handle and analyze the data are used. This (common) practice complicates the exchange of data, methods, and research results. In contrast, an object-oriented approach, developed in cooperation with a project on Open Information Systems, is compared with classical concepts. The results show that object-oriented data modelling can facilitate user access to multiple datasets, support integrated use of different analysis technologies, and could aid in the development of standards for exchanging data in a multidisciplinary environment.