Stereophotogrammetry of archive data and topographic approaches to debris‐flow torrent measurements: calculation of channel‐sediment states and a partial sediment budget for Manival torrent (Isère, France)

Abstract

This paper focuses on a topographic methodology to characterize the amount of sediment stored in channels and the use of historical photographs for aerial survey by stereophotogrammetry, as part of wider research on debris-flow magnitude prediction. The topographic methodology uses equidistant four-point cross-sections along the long profile of the channel. Each cross-section is representative of a 50-m reach of the channel. To calculate the volume of each reach, the difference is calculated between a reference level and the topographic surface. The reference level is the lowest level where the debris flow can erode, and in the current method this level is estimated from fixed points along the long profile of the channel. The accuracy of the method has been estimated by comparing results of a detailed topographic survey, with a standard deviation corresponding to about 6 per cent of the total calculated sediment volume.This topographic methodology has been used on aerial photographs by photogrammetry. This tool was applied to photographs taken on 12 past dates. The scales of the archive photographs used range from 1:3000 to 1:30 000, but results are consistent and permit us to calculate sediment states of the channel for different past dates with an uncertainty of about 6 per cent of the total volume. The application of the technique to the Manival debris-flow torrent has permitted us to propose some partial sediment budgets and erosion-rate estimates.

The role of the sediment budget in understanding debris flow susceptibility

“…, however, used a method proposed by Oden (1994) to estimate the volume of debris stored in a PDFT. Topographic methodology using historical photographs is also available to characterize the amount of sediment stored in channels (Veyrat-Charvillon and Memier, 2006). This study subjectively estimates the volume of debris stored in the catchment of PDFTs in the field by geologists, though the field investigation is time consuming and costly.…”

“…Sediment-budget estimation in mountains terrain (sediment storage, contribution, and output) is an important issue which attracts much attention in the research field of earth science at different scales (Innes, 1983;Hungr et al, 1984;Takei, 1984;VanDine, 1985;Oden, 1994;Rickenmann, 1999;Bianco and Franzi, 2000;Franzi and Bianco, 2001;Helsen et al, 2002;Johnson and Warburton, 2002;Martin et al, 2002;Walling et al, 2002;Charlton et al, 2003;French, 2003;Schrott et al, 2003;Guthrie and Evans, 2004;Marchi and D'Agostino, 2004;de Vente et al, 2006;Schuerch et al, 2006;Veyrat-Charvillon and Memier, 2006;Morche et al, 2008). This study proposes a simplified sediment-budget model to provide a simple way to estimate the temporal variation of debris volume stored in the debrisflow prone watershed.…”

Monitoring and reconstructing past biogeomorphic succession within fluvial corridors using stereophotogrammetry

“…Traditionally, photogrammetry was used as a tool to create DTMs, for example for the modelling of terrestrial landform evolution (Chandler, 1999;Brown and Arbogast, 1999;Lane, 2000;Baily et al, 2003;Veyrat-Charvillon and Memier, 2006;Walstra et al, 2007;Baldi et al, 2008;Lane et al, 2010). Traditionally, photogrammetry was used as a tool to create DTMs, for example for the modelling of terrestrial landform evolution (Chandler, 1999;Brown and Arbogast, 1999;Lane, 2000;Baily et al, 2003;Veyrat-Charvillon and Memier, 2006;Walstra et al, 2007;Baldi et al, 2008;Lane et al, 2010).…”

Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

“…2b, c). This reach of the Manival torrent has received considerable attention by RTM since the late 19th century (Veyrat-Charvillon and Memier, 2006): in 1926, two 150 and 230-m long dykes were built on both sides of the active channel ( Fig. 2c), leading to an open central …”