Disturbance regime landscapes: mountain drainage systems interrupted by large rockslides

The paper examines the role of rockslide-rock avalanches in mountain landscapes, and the landforms associated with them. While the landslides are extremely short-lived events, rock wall detachment scars and rock avalanche deposits can persist for long periods as influences on landscape development. Especially significant are rock avalanches with complex runout and emplacement related to interactions with rugged terrain or deformable substrates. Their characteristics greatly increase the scope of landscape disturbance. Hundreds of rock avalanches are now known, worldwide, that have formed crossvalley barriers interrupting mountain drainage systems. Many have done so for millennia or tens of millennia. They give rise to distinctive sediment assemblages, constructional and erosion landforms generated by other processes responding to the landslides and constrained by them. A landslide interruption epicycle of five phases is described, and related sediment assemblages. These provide the basis for defining a landslide interrupted valley landsystem. Its full significance is seen in mountain drainage basins affected by multiple landslide interruptions. These create naturally fragmented fluvial systems, in which a disturbance regime geomorphology is identified. Stream profiles, sediment delivery, and related landforms are kept in a chronic state of disequilibrium with respect to climatic and geotectonic controls, and drainage organization. The transHimalayan Upper Indus Basin provides an example, a large high mountain drainage system fragmented by more than 170 late Quaternary rock avalanches. In this case, as elsewhere, misidentification of rock avalanches led to neglect of their role in Quaternary histories. The nature and limitations of disturbance regime geomorphology are discussed, and broader implications for mountain landscapes.

[1]  L. Masch,et al.  Quaternary landslides and rock fusion in Central Nepal and in the Tyrolean Alps. , 1984 .

[2]  O. Hungr,et al.  The Avalanche Lake rock avalanche, Mackenzie Mountains, Northwest Territories, Canada: description, dating, and dynamics , 1994 .

[3]  P. Freytet,et al.  Lacustrine Sedimentation in a Semiarid Alpine Setting: An Example from Ladakh, Northwestern Himalaya , 1989, Quaternary Research.

[4]  Oliver Korup,et al.  Geomorphometric characteristics of New Zealand landslide dams , 2004 .

[5]  M. Strecker,et al.  Structural and lithological controls on large Quaternary rock avalanches (sturzstroms) in arid northwestern Argentina , 1999 .

[6]  J. Shroder.  Himalaya to the sea : geology, geomorphology, and the Quaternary , 1993 .

[7]  Kenneth J. Hsü,et al.  Catastrophic Debris Streams (Sturzstroms) Generated by Rockfalls , 1975 .

[8]  W. Graf.  Catastrophe Theory as a Model for Change in Fluvial Systems , 1979 .

[9]  J. C. Yarnold,et al.  A Facies Model for Large Rock-Avalanche Deposits Formed in Dry Climates , 1989 .

[10]  G. Eisbacher.  Destructive Mass Movements in High Mountains , 1984 .

[11]  Landslides: extent and economic significance. , 1989 .

[12]  M. Macklin,et al.  River Basin Sediment Systems: Archives of Environmental Change , 2001 .

[13]  K. Hewitt.  Catastrophic landslides and their effects on the Upper Indus streams, Karakoram Himalaya, northern Pakistan , 1998 .

[14]  John E. Costa,et al.  The formation and failure of natural dams , 1988 .

[15]  Nicholas Brozovic,et al.  Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas , 1996, Nature.

[16]  J. Loup.  Voight (Barry), éditeur. — Rockslides and avalanches, 1, Natural phenomena , 1978 .

[17]  M. Sorriso-Valvo,et al.  Geomorphic controls of the shape and mobility of rock avalanches , 1991 .

[18]  C. Nilsson,et al.  Fragmentation and Flow Regulation of River Systems in the Northern Third of the World , 1994, Science.

[19]  M. McSaveney.  Recent rockfalls and rock avalanches in Mount Cook National Park, New Zealand , 2002 .

[20]  H. Kelsey.  Formation of inner gorges , 1988 .

[21]  A. Hauser.  Rock avalanche and resulting debris flow in Estero Parraguirre and Río Colorado, Region Metropolitana, Chile , 2002 .

[22]  G. Wieczorek.  Catastrophic rockfalls and rockslides in the Sierra Nevada, USA , 2002 .

[23]  K. J. Miller,et al.  The International Karakoram Project , 1985 .

[24]  D. Cruden.  Rock slope movements in the Canadian Cordillera , 1985 .

[25]  K. Hewitt.  Catastrophic rockslides and the geomorphology of the Hunza and Gilgit River Valleys, Karakoram Himalaya , 2001 .

[26]  Andrew J. Pearce,et al.  Effects of earthquake-induced landslides on sediment budget and transport over a 50-yr period , 1986 .

[27]  K. Hewitt.  Catastrophic Landslide Deposits in the Karakoram Himalaya , 1988, Science.

[28]  A. Braathen,et al.  Rock-slope failures in Norway ; type , geometry , deformation mechanisms and stability , 2004 .

[29]  K. Hewitt.  Natural dams and outburst floods of the Karakoram Himalaya , 1982 .

[30]  C. Cotton.  Geomorphology : an introduction to the study of landforms , 1952 .

[31]  M. Fort,et al.  Glaciers and mass wasting processes: their influence on the shaping of the Kali Gandaki valley (higher Himalaya of Nepal) , 2000 .

[32]  Adrian E. Scheidegger,et al.  On the prediction of the reach and velocity of catastrophic landslides , 1973 .

[33]  Kenneth Hewitt,et al.  Quaternary Moraines vs Catastrophic Rock Avalanches in the Karakoram Himalaya, Northern Pakistan , 1999, Quaternary Research.

[34]  Neogene sturzstrom deposits, Split Mountain area, Anza-Borrego Desert State Park, California , 2002 .

[35]  R. Schuster,et al.  Overview of catastrophic landslides of South America in the twentieth century , 2002 .

[36]  Jan Cornelius Schmidt,et al.  Dams and rivers: a primer on the downstream effects of dams , 1996 .

[37]  G. Eisbacher.  Cliff collapse and rock avalanches (sturzstroms) in the Mackenzie Mountains, northwestern Canada , 1979 .

[38]  J. Shroder,et al.  Quaternary glacial chronology and neotectonics in the Himalaya of northern Pakistan , 1989 .

[39]  S. Schumm.  Episodic Erosion: A Modification of the Geomorphic Cycle, , 1976 .

[40]  David J. A. Evans,et al.  Glaciers and Glaciation , 1997 .

[41]  Andreas von Poschinger,et al.  Large rockslides in the Alps: A commentary on the contribution of G. Abele (1937–1994) and a review of some recent developments , 2002 .

[42]  G. Vorndran.  Abele, Gerhard: Bergstürze in den Alpen - ihre Verbreitung. Morphologie und Folgeerscheinungen , 1977 .

[43]  L. Owen.  Mass movement deposits in the Karakoram Mountains: their sedimentary characteristics, recognition and role in Karakoram landform evolution , 1991 .

[44]  I. E. Whitehouse.  Distribution of large rock avalanche deposits in the central Southern Alps, New Zealand , 1983 .

[45]  N. L. Falcon,et al.  An Ancient Landslip at Saidmarreh in Southwestern Iran , 1938, The Journal of Geology.

[46]  Jonathan D. Phillips,et al.  Sources of nonlinearity and complexity in geomorphic systems , 2003 .

[47]  L. Owen,et al.  QUATERNARY AND HOLOCENE INTERMONTANE BASIN SEDIMENTATION IN THE KARAKORAM MOUNTAINS , 1993 .

[48]  N. Pollet,et al.  Effects of the internal structure of a rock–avalanche dam on the drainage mechanism of its impoundment, Flims sturzstrom and Ilanz paleo-lake, Swiss Alps , 2004 .

[49]  P. Laznicka.  Breccias and Coarse Fragmentites: Petrology, Environments, Associations, Ores , 1988 .

[50]  Tianchi Li.  Mountain hazards in China , 2004 .

[51]  Jerome V. DeGraff,et al.  Catastrophic landslides : effects, occurrence, and mechanisms , 2002 .

[52]  R. Schuster,et al.  Landslide Dams : Processes, Risk, and Mitigation , 1986 .

[53]  Lionel E. Jackson.  Landslides and landscape evolution in the Rocky Mountains and adjacent Foothills area, southwestern Alberta, Canada , 2002 .

[54]  P. Tchilinguirian,et al.  Villavil rockslides, Catamarca Province, Argentina , 2002 .

[55]  L. Benda,et al.  Debris flows as agents of morphological heterogeneity at low-order confluences, Olympic Mountains, Washington , 2003 .