Climate-Driven Bedrock Incision in an Active Mountain Belt

Hartshorn, K.; Hovius, Niels; Dade, W. Brian; Slingerland, Rudy

doi:10.1126/science.1075078

Cited by 233 publications

(255 citation statements)

References 17 publications

(21 reference statements)

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“…Floods efficiently erode and transport sediment stored in the riverbed (Baker and Kale, 1998;Bookhagen et al, 2005;Coppus and Imeson, 2002;Hartshorn et al, 2002). On 26 June 2005, a flood occurred in the Parechu River, a main tributary of the Spiti River, which was caused by the failure of a landslide dam that blocked the river (cf.…”

Section: The 26 June 2005: Parechu Floodmentioning

confidence: 99%

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

Wulf

Bookhagen

Scherler

2012

Hydrol. Earth Syst. Sci.

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Abstract. The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature and earthquake records, and field observations, we infer climatic and geologic controls of peak suspended sediment concentration (SSC) events. Our study identifies three key findings: First, peak SSC events (≥ 99th SSC percentile) coincide frequently (57-80 %) with heavy rainstorms and account for about 30 % of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan Front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments, we find an anticlockwise hysteresis loop of annual sediment flux variations with respect to river discharge, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacialmeltwater contributions. In future climate change scenarios, including continuous glacial retreat and more frequent monsoonal rainstorms across the Himalaya, we expect an increase in peak SSC events, which will decrease the water quality and impact hydropower generation.

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Section: The 26 June 2005: Parechu Floodmentioning

confidence: 99%

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

Wulf

Bookhagen

Scherler

2012

Hydrol. Earth Syst. Sci.

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“…For example, Hartshorn et al [2002] argued that valley lowering is driven by frequent, moderate intensity floods which mobilize the coarse bed load and abrade underlying bedrock while D'Arcy and Whittaker [2014] found that channel steepness is significantly suppressed by higher precipitation due to a concomitant increase in stream power. Hillslopes are then expected to passively follow decreased or increased rates of base-level lowering by either (a) steepening or lowering hillslope angle: in transport-limited (soil mantled) conditions, the rate of soil creep/mass movement will slowly change due to a change in base level and increased/decreased soil diffusivity [Fernandes and Dietrich, 1997]; or (b) in high-relief terrain maintain roughly linear (threshold) hillslopes but increase/decrease the rate of landsliding [Burbank et al, 1996;Tucker and Bras, 1998;Tucker and Hancock, 2010].…”

Section: Introductionmentioning

confidence: 99%

“…Instead, by controlling the sediment supply to adjacent channels, hillslope processes directly influence channel dynamics, i.e., hillslope processes may respond to changing precipitation by either increasing or decreasing the sediment supply to adjacent channels which either enhances or impedes fluvial wear of the channel. Thus, both hillslopes and channels respond independently and interdependently [Brunsden and Thornes, 1979;Brunsden, 1993;Sklar and Dietrich, 1998;Hartshorn et al, 2002;Dietrich et al, 2003;Turowski et al, 2013;Finnegan et al, 2014;Michaelides and Singer, 2014] to changing precipitation and it is far from clear which leads the response or whether indeed their coupling means that they respond simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Landscape reorganization under changing climatic forcing: Results from an experimental landscape

Singh

Reinhardt

Foufoula‐Georgiou

2015

Water Resources Research

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Understanding how landscapes respond to climate dynamics in terms of macroscale (average topographic features) and microscale (landform reorganization) is of interest both for deciphering past climates from today's landscapes and for predicting future landscapes in view of recent climatic trends. Although several studies have addressed macro-scale response, only a few have focused on quantifying smaller-scale basin reorganization. To that goal, a series of controlled laboratory experiments were conducted where a self-organized complete drainage network emerged under constant precipitation and uplift dynamics. Once steady state was achieved, the landscape was subjected to a fivefold increase in precipitation (transient state). Throughout the evolution, high-resolution spatiotemporal topographic data in the form of digital elevation models were collected. The steady state landscape was shown to possess three distinct geomorphic regimes (unchannelized hillslopes, debris-dominated channels, and fluvially dominated channels). During transient state, landscape reorganization was observed to be driven by hillslopes via accelerated erosion, ridge lowering, channel widening, and reduction of basin relief as opposed to channel base-level reduction. Quantitative metrics on which these conclusions were based included slope-area curve, correlation analysis of spatial and temporal elevation increments, and wavelet spectral analysis of the evolving landscapes. Our results highlight that landscape reorganization in response to increased precipitation seems to follow ''an arrow of scale'': major elevation change initiates at the hillslope scale driving erosional regime change at intermediate scales and further cascading to geomorphic changes at the channel scale as time evolves.

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“…Finally, erosion could occur directly due to the stresses exerted by the fluid on the rock. Although all of the processes in these four groups occur in different locations and at different times, and may interact to produce the erosional result, corrasion is probably the dominant mechanism in high-energy natural environments such as many mountain rivers (Hancock et al, 1998;Hartshorn, Hovius, Dade, & Slingerland, 2002;Wilson et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The influence of sediment thickness on energy delivery to the bed by bedload impacts

Turowski

Bloem

2015

Geodinamica Acta

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Fluvial bedrock erosion rates due to impacting sediment particles are thought to be proportional to the energy delivered to the bedrock. When sediment particles cover the bed, they reduce the energy transmitted to the bed by an impacting particle. We measured the decline of energy transferred through sediment cover of increasing thickness in laboratory experiments. The energy arriving at the bed is a function both of the cover thickness and the grain size of the covering sediment. Using a simple stochastic model of cover distribution, the experimental results were upscaled to the reach scale. Although cover thickness influences energy delivery heavily at a given point, when averaging over the whole bed, cover-free areas dominate total energy delivery, making partial energy transfer through the cover negligible when a small or intermediate fraction of the bed is covered by sediment. Partial energy delivery through the bed cover is not negligible when a large fraction or the complete bed is already covered, but in this situation, an erosion threshold may become important. On grounds of the presented data, we expect that the areal distribution of sediment in a bedrock channel dominates total energy delivery and that partial energy delivery to the bed through a sediment layer can be neglected for most modelling purposes.

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Climate-Driven Bedrock Incision in an Active Mountain Belt

Cited by 233 publications

References 17 publications

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

Landscape reorganization under changing climatic forcing: Results from an experimental landscape

The influence of sediment thickness on energy delivery to the bed by bedload impacts

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