Geo‐botanical evidence of late quaternary mass wasting in block field areas of Virginia

Hupp, Cliff R.

doi:10.1002/esp.3290080505

Cited by 41 publications

(29 citation statements)

References 13 publications

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“…Cores were also visually inspected to identify further signs of past debris-flow activity. For instance, the corrasion of stems causes cambium damage (cambium = wood-producing tissue of trees) and results in the formation of callus tissue overgrowing these scars (Hupp 1984). Another typical feature in injured L. decidua and P. abies are tangential rows of traumatic resin ducts (TRD; Stoffel 2008), formed as a means of protection against insect and pathogen attacks following cambium damage (e.g., Bollschweiler et al 2008b;Stoffel and Hitz 2008;Schneuwly et al 2009a, b).…”

Section: Dendrogeomorphic Reconstruction Of Past Debris Flowsmentioning

confidence: 99%

Rainfall characteristics for periglacial debris flows in the Swiss Alps: past incidences–potential future evolutions

2011

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Based on observational meteorological data since A.D. 1864 and tree-ring records of debris-flow activity, this paper assesses changes in rainfall characteristics and their impact on the triggering of geomorphic events in a high-elevation watershed of the Swiss Alps since the end of the Little Ice Age. No trends are visible in the frequency of heavy rainfall events, but we observe a reduced number of heavy, shortlived rainfalls in summer and a concentration of advective storms is recorded in late summer and early fall since the late 1980s. These changes in triggering meteorological conditions resulted in a cluster of debris flows in the early decades of the twentieth century and a lowering of debris-flow activity since the mid 1990s, and may be mirroring the observed changes in persistent high-pressure systems over the Alps. We also observe intra-seasonal differences in debris-flow system response reflecting the state of the permafrost body in the source area of debris flows, allowing for very small debris flows to be released by limited rainfall inputs (<20 mm) in June and July. The same quantities of rain will not trigger debris flows in August or September, when a thick active layer of the permafrost body is capable of absorbing water. With the projected amplitude of climatic change, seasonality, return intervals and volumes of debris flows are likely to be altered. RCM projections based on the IPCC A2 scenario suggest a decrease in heavy summer rainfalls which will most likely result in a (further) reduction of the overall frequency of debris flows, leaving more time for sediment to accumulate in the channel. Such an increase of channel accumulation rates along with the projected destabilization of the steep rock-glacier body is likely, M. Stoffel (B) · M. Bollschweiler · M. Beniston

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Section: Dendrogeomorphic Reconstruction Of Past Debris Flowsmentioning

confidence: 99%

Rainfall characteristics for periglacial debris flows in the Swiss Alps: past incidences–potential future evolutions

2011

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“…3. Tree-ring 'signatures' used to determine the age of debris-flow deposits (drawing modified after Hupp, 1984).…”

Section: Debris-flow Frequency and Timing Of Eventsmentioning

confidence: 99%

Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: Chronology, environment and implications for the future

Stoffel

Conus

Grichting

et al. 2008

Global and Planetary Change

121

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Debris-flow activity on the forested cone of the Ritigraben torrent (Valais, Swiss Alps) was assessed from growth disturbances in century-old trees, providing an unusually complete record of past events and deposition of material. The study of 2246 tree-ring sequences sampled from 1102 Larix decidua Mill., Picea abies (L.) Karst. and Pinus cembra ssp. sibirica trees allowed reconstruction of 123 events since AD 1566. Geomorphic mapping permitted identification of 769 features related to past debrisflow activity on the intermediate cone. The features inventoried in the study area covering 32 ha included 291 lobes, 465 levées and 13 well-developed debris-flow channels. Based on tree-ring records of disturbed trees growing in or next to the deposits, almost 86% of the lobes identified on the present-day surface could be dated. A majority of the dated material was deposited over the last century. Signs of pre-20th century events are often recognizable in the tree-ring record of survivor trees, but the material that caused the growth anomaly in trees has been completely overridden or eroded by more recent debris-flow activity.Tree-ring records suggest that cool summers with frequent snowfalls at higher elevations regularly prevented the release of debris flows between the 1570s and 1860s; the warming trend combined with greater precipitation totals in summer and autumn between 1864 and 1895 provided conditions that were increasingly favorable for releasing events from the source zone. Enhanced debris-flow activity continued well into the 20th century and reconstructions show a clustering of events in the period 1916-1935 when warm-wet conditions prevailed during summer in the Swiss Alps. In contrast, very low activity is observed for the last 10-yr period (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) with only one debris-flow event recorded on August 27, 2002. Since sediment availability is not a limiting factor, this temporal absence of debris-flow activity is due to an absence of triggering events, which not only shifted from June and July to August and September over the 20th century, but also seemed to be initiated primarily by persistent precipitation rather than summer thunderstorms. From the reconstructions, based on RCM simulations, there are indications that debris-flow frequencies might continue to decrease in the future, as precipitation events are projected to occur less frequently in summer but become more common in spring or autumn.

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“…The formation of callus tissue was interpreted as a reaction to the corrasion of tree stems by the flow that causes cambium damage and scars (Hupp, 1984).…”

Section: Sign Of Disturbance In the Tree-ring Recordmentioning

confidence: 99%

“…Strunk, 1997;Bollschweiler and Stoffel, 2010b) and magnitude (e.g. Hupp, 1984;Stoffel, 2010). Spatial patterns of previous activity on cones and in channels have also repeatedly been compared with archival records on flooding (e.g.…”

Section: Introductionmentioning

confidence: 99%

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

Lopez-Saez¹,

Corona²,

Stoffel

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. Hydrogeomorphic processes are a major threat in many parts of the Alps, where they periodically damage infrastructure, disrupt transportation corridors or even cause loss of life. Nonetheless, past torrential activity and the analysis of areas affected during particular events remain often imprecise. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris-flow activity in abandoned channels on the forested cone of the Manival torrent (Massif de la Chartreuse, French Prealps). A Light Detecting and Ranging (LiDAR) generated Digital Elevation Model (DEM) was used to identify five abandoned channels and related depositional forms (lobes, lateral levees) in the proximal alluvial fan of the torrent. A total of 156 Scots pine trees (Pinus sylvestris L.) with clear signs of debris flow events was analyzed and growth disturbances (GD) assessed, such as callus tissue, the onset of compression wood or abrupt growth suppression. In total, 375 GD were identified in the tree-ring samples, pointing to 13 debris-flow events for the period 1931-2008. While debris flows appear to be very common at Manival, they have only rarely propagated outside the main channel over the past 80 years. Furthermore, analysis of the spatial distribution of disturbed trees contributed to the identification of four patterns of debris-flow routing and led to the determination of three preferential breakout locations. Finally, the results of this study demonstrate that the temporal distribution of debris flows did not exhibit significant variations since the beginning of the 20th century.

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Geo‐botanical evidence of late quaternary mass wasting in block field areas of Virginia

Cited by 41 publications

References 13 publications

Rainfall characteristics for periglacial debris flows in the Swiss Alps: past incidences–potential future evolutions

Rainfall characteristics for periglacial debris flows in the Swiss Alps: past incidences–potential future evolutions

Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: Chronology, environment and implications for the future

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

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