Slope evolution and landslides --- concepts, methods & some implications for data management
Presentation at
4th International conference on GeoComputation, Fredericksburg, VA
25July1999
Jochen Schmidt and Holger Gärtner and Richard Dikau
Abstract.
It is an open research question to which extend 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. Research aim of the coupled use of these different unknown boundary conditions in time, (2) discontinuity of the process, (3) different process types, (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 itentified 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 (see below). First results show the dependency of landslide occurence in the Bonn area on hillslope morphometry and geology. These findings are used in an 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 (Germany) 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 multidisciplinary environment.