On Landslide And Debris Flow Volume And Location
Abstract
Traditional methods of estimating the potential of landsliding and mass movements in mountains are based on surveys which estimate the quaternary depositions and the volumes of sediments available in areas whose geomorphic characters warn for pos- sible landslide. These methods use also geo-lithological and land-use information to finally produce maps of the location of landslides and debris flow initiaton. To actually estimate their volumes, empirical formulas are used which also relies on geomoprpho- logical analyses.
We claim that the traditional procedure can be succesfully coupled and greatly en- hanced by the use of modern tecniques based on accurate DEMs and a simplified but quantitative hydrological modelling. Sediment volumes released in extreme events derives either (a) from hillslopes (in this case we usually refer to them as lanslides) or (b) from concave unchanneled valleys and torrent beds (and are usually referred as debris flows) and are the product of (1) mass failure and (2) dynamical entrainment during the mass run-out. Mass failure (1) has many origins. Here we discuss only those cases which are dependent on water flow and hence are dominated by water fluxes during storms and their redistribution during interstorms and propose a simple extension of the SHALSTAB model of Di- etrich et al. (1994) which introduces a suitable GIS based soil depth estimation. The effects of the dynamical entrainment (2) instead depend on sediment availability and the extremely complex dynamical conditions of the water-sediment mixture during his downslope motion. However, we show that, assuming sufficient sediment deposits, a gross estimation can be indeed obtained by an extension of the Takahashi theory and utilizing some recents semi-analytical results of the theory of the Geomorphological Unith Hydrograph.- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.4956R