科研之友
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摘要
A method based on dendrochronology was developed to analyse the spatial and temporal variability of landslide activity as an alternative and complement to methods such as field monitoring of landslide relief, aerial-photography, and remote sensing. The method involves a feature of wood anatomy, tree-ring eccentricity, which is used in the dating procedure. The degree of eccentricity is used as an indicator of the intensity of the mechanical stress affecting a tree stem in a certain year. The objective was to develop a mathematical indicator of tree-ring eccentricity for dating the recent dynamics of landslides. A method presented in the paper is also designed for practical application in detecting initial landslide activity and allowing the determination of triggering factors. The index developed is dimensionless and for this reason is independent of the absolute ring variations of the single trees analysed. Using reference results (from stable slopes) as thresholds in dating an objective method for detecting landslide activity was developed. The method was used in the Carpathian and Sudeten Mountains on three landslides with different sizes and geological settings. It was found that the values of eccentricity index in trees growing on stable slopes rarely exceed at +/- 100%, while in trees growing on landslides they can reach hundreds to thousands per cent. A spatial analysis of the eccentricity values conducted for a single landslide has revealed that the method developed allows one to identify areas of landslide activation and to observe the down- or upslope propagation of instability. A comparison of the results obtained regarding the precipitation record has shown that, by using the method that has been developed, it is possible to detect past mass-movement episodes caused by heavy, long-term rainfall as well as by single, short-lasting but torrential downpours.
- 出版日期2013-12
