Spatial and temporal variability of sediment transfer and storage in an Alpine basin (Reintal valley, Bavarian Alps, Gemany)

Abstract

Abstract. This paper focuses in particular on clastic sediment fluxes on talus slopes. Using orthophoto interpretation, field measurements and GIS-techniques, a quantification of areas and volumes of active sediment transfer related to specific landform units was achieved for different spatial scales. Closer investigation of a single landform complex, more specifically a talus sheet/ debris cone-complex, brought to light that remobilisation can overbalance sediment input by a factor of 57. This could be an indication of what may be expected in the whole catchment. At present. approximately 9% of the research area (3 km2), comprising talus slopes and valley bottom, is characterised by sediment transfer mainly through gravilational and fluvial processes. A comparison of the vast volumes (117.174 m3) derived from these active areas of recent sediment transfer and the volume of the entire valley fill (0.07 km3) indicates, however, that the largest part must be related to remobilised sediments and cannot be considered as sediment input from the adjacent rockwalls. This conclusion is also supported by direct measurements of sediment input.

Volume changes of Alpine sediment stores in a state of post-event disequilibrium and the implications for downstream hydrology and bed load transport

“…4). Until summer 2005 the talus cone surface showed no geomorphological activity (rock fall, debris flow, fluvial erosion), though other sediment stores in the Reintal valley were affected by surface geomorphic processes (Schrott et al 2006;Heckmann et al 2008). This stable state was documented by the dark coloured coatings of the limestone debris on the surface and by the vegetation cover (Fig.…”

“…Location of the study area. VBG 0Vordere Blaue Gumpe (0 m), an alluvial plain investigated by Morche et al (2006) by analyses historical maps and geodetic surveys, with ground penetrating radar and this study with geodetic survey; TS/DC 0talus sheet/debris cone complex (0Á300 m channel reach downstream of the outlet of VBG) investigated by Heckmann et al (2008), and Schrott et al (2006); TC0talus cone (1700 m) (surveyed with terrestrial laser scanning, this study); and GSB 0gauging station Bockhuette at the outlet of the catchment (2100 m) (discharge and sediment transport measurements by , Morche et al (2008) NORSK GEOGRAFISK TIDSSKRIFT 62 (2008) talus slopes surveyed by can be transferred to the talus cone investigated by laser scanning in our study. According to the findings of dendrogeomorphological investigations by Koch (2005), the talus cone is debris flow dominated rather than rockfall dominated.…”

“…The subsystems are coupled in a sediment cascade by different geomorphic processes (rockfalls, avalanches, debris flows, fluvial processes). However, the functional activity of the geomorphic coupling varies over time and is dependent on sediment availability and triggering events (Schrott et al 2006;Morche et al 2007). Sediment storage types in alpine geosystems are primarily formed by gravitational and nival processes and destroyed by fluvial processes (Becht et al 2005;Morche et al 2006;Schrott et al 2006;Krautblatter et al in press).…”

“…However, the functional activity of the geomorphic coupling varies over time and is dependent on sediment availability and triggering events (Schrott et al 2006;Morche et al 2007). Sediment storage types in alpine geosystems are primarily formed by gravitational and nival processes and destroyed by fluvial processes (Becht et al 2005;Morche et al 2006;Schrott et al 2006;Krautblatter et al in press). The formation of storage systems and their subsequent geomorphological decoupling may last for hundreds or thousands of years (Hewitt 2006;Fryirs et al 2007;Heckmann et al 2008;).…”

Geomorphic coupling and sediment connectivity in an alpine catchment — Exploring sediment cascades using graph theory

“…If such a segmentation aims at an area-wide classification of land surface (rather than extracting a specific landform type), the task is especially difficult (Evans, 2012). Yet, automated and manual methods towards landscape segmentation based on morphology and remote sensing imagery exist (Dikau, 1989;Dragut and Eisank, 2011), some of them with direct links to sediment cascades (Schneevoigt et al, 2008), toposequences (Otto et al, 2009) or spatial interactions of geomorphic processes (GPUs, e.g., Schrott et al, 2006;Bartsch et al, 2009;Wichmann et al, 2009). For the channel network, Leviandier et al (2012) suggest and compare statistical procedures for separating homogeneous river reaches; however, the linkage of such reaches would still have to be assessed manually or by using models.…”