A quantitative model for integrating landscape evolution and soil formation

Vanwalleghem, Tom; Stockmann, Uta; Minasny, Budiman; McBratney, Alex B.

doi:10.1029/2011jf002296

Cited by 117 publications

(89 citation statements)

References 100 publications

(166 reference statements)

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“…Such a relationship has been evidenced in several environments [Heimsath et al, 1997[Heimsath et al, , 2012, especially when applied to soil thickness, where soil is the upper part of the regolith that is actively transported by surface processes. This relationship has also served as the basis of many conceptual and numerical models of regolith and/or soil formation and, coupled with a model of surface transport and erosion, has been used to explain the dynamics of regolith-mantled hillslopes and, more generally, the distribution of regolith thickness in mountain belts [Braun et al, 2001;Ferrier and Kirchner, 2008;Yoo et al, 2009;Gabet and Mudd, 2009;Vanwalleghem et al, 2013;Carretier et al, 2014]. A slightly more evolved or so-called "humped" relationship has been introduced by Carson and Kirkby [1972] to account for the fact that under thin soil/regolith or exposed bedrock conditions, surface runoff dominates and chemical weathering is reduced, an observation already made by Gilbert [1877] in the Henry Mountains.…”

Section: General Concepts and Existing Modelsmentioning

confidence: 99%

A simple model for regolith formation by chemical weathering

et al. 2016

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We present here a new model for the formation of regolith on geological timescales by chemical weathering based on the assumption that the rate of chemical weathering is primarily controlled by the ability of groundwater to transport solute away from the reacting solid‐fluid interface and keep the system from reaching equilibrium (saturation). This allows us to specify the rate of propagation of the weathering front as linearly proportional to the pore fluid velocity which we obtain by computing the water table geometry in the regolith layer. The surface of the regolith layer is affected by mass transport and erosion. The main prediction of the model is that the geometry of the regolith, i.e., whether it is thickest beneath topographic highs or topographic lows, is controlled by the value of a dimensionless number, which depends on the square of the surface slope, the hydraulic conductivity, and local precipitation rate, but is independent of the chemical weathering rate. In orogenic environments, where regolith formation by chemical weathering competes with surface erosion, the model predicts that the existence and thickness of the regolith layer are controlled by the value of another dimensionless number which is the ratio between the timescale for erosion and the timescale for weathering. The model also predicts that in anorogenic areas, regolith thickness increases as the square root of time, whereas in orogenic environments, a steady state regolith thickness can be achieved, when the propagation of the weathering front is equal to erosion rate.

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Section: General Concepts and Existing Modelsmentioning

confidence: 99%

A simple model for regolith formation by chemical weathering

et al. 2016

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“…These two last points constitute the main differ-490 ences of our approach compared to previous pedon and landscape weathering models (e.g. Ferrier and Kirchner, 2008;Vanwalleghem et al, 2013;Braun et al, 2016 All previous models founded on clast residence time in the regolith predict that weathering should be zero when the regolith disappears (e.g. Ferrier and Kirchner, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, few models (Vanwalleghem et al, 2013;Braun et al, 2016) account for the heterogeneity of erosion and weathering during relief adaptation to uplift which may control the overall evolution of the weathering rate of a rising mountain range (Anderson et al, 2012;Cohen et al, 2013;Carretier et al, 2014). None of these models can be used to trace the weathered material through its stochastic 50 displacement from the hillslopes to the basins.…”

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confidence: 99%

“…The removal of water by plants, changes in the regolith porosity, pCO2, groundwater flow velocity, pH, sensitivity of the surface temperature variations, clay precipitation, etc., can modify the 225 weathering rate according to the depth. In the future, this could be accounted for by, for example, modulating the weathering rate by the same humped law (Equation 7) used for regolith production (Vanwalleghem et al, 2013).…”

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confidence: 99%

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Colluvial deposits as a possible weathering reservoir in uplifting mountains

Carretier¹,

Goddéris²,

Martı́nez³

et al. 2017

Preprint

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Abstract. The role of mountain uplift in the global climate over geological times is controversial.At the heart of this debate is the capacity of rapid denudation to drive silicate weathering, a CO 2 consumer. Here we present the results of a 3D model that couples erosion and weathering during mountain uplift, in which the weathered material is traced during its stochastic transport from the hillslopes to the mountain outlet. During mountain uplift, the erosion rate increases and the climate 5 cools, which thins the regolith and produces a hump in the weathering rate evolution. Nevertheless, lateral river erosion drives mass wasting and the temporary storage of colluvial deposits on the valley borders. This new reservoir is comprised of fresh material which has a residence time ranging from several years up to several thousand years. During this period, the weathering of colluvium sustains the mountain weathering flux at a significant level. The relative weathering contribution 10 of colluvium depends on the area covered by regolith on the hillslopes. For mountains sparsely covered by regolith during cold periods, colluvium produce most of the simulated weathering flux for a large range of erosion parameters and precipitation rate patterns. In addition to other reservoirs such as deep fractured bedrock, colluvial deposits may help to maintain a substantial and constant weathering flux in rapidly uplifting mountains during cooling periods.

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“…Some modelling studies have incorporated depth-dependent bioturbation mixing, e.g. Vanwalleghem et al (2013), and there are a few detailed models of cryoturbation, e.g. Peterson et al (2003).…”

Section: Vertical Discretizationmentioning

confidence: 99%

A vertical representation of soil carbon in the JULES land surface scheme (vn4.3_permafrost) with a focus on permafrost regions

2017

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Abstract. An improved representation of the carbon cycle in permafrost regions will enable more realistic projections of the future climate-carbon system. Currently JULES (the Joint UK Land Environment Simulator) -the land surface model of the UK Earth System Model (UKESM) -uses the standard four-pool RothC soil carbon model. This paper describes a new version of JULES (vn4.3_permafrost) in which the soil vertical dimension is added to the soil carbon model, with a set of four pools in every soil layer. The respiration rate in each soil layer depends on the temperature and moisture conditions in that layer. Cryoturbation/bioturbation processes, which transfer soil carbon between layers, are represented by diffusive mixing. The litter inputs and the soil respiration are both parametrized to decrease with increasing depth. The model now includes a tracer so that selected soil carbon can be labelled and tracked through a simulation. Simulations show an improvement in the large-scale horizontal and vertical distribution of soil carbon over the standard version of JULES (vn4.3). Like the standard version of JULES, the vertically discretized model is still unable to simulate enough soil carbon in the tundra regions. This is in part because JULES underestimates the plant productivity over the tundra, but also because not all of the processes relevant for the accumulation of permafrost carbon, such as peat development, are included in the model. In comparison with the standard model, the vertically discretized model shows a delay in the onset of soil respiration in the spring, resulting in an increased net uptake of carbon during this time. In order to provide a more suitable representation of permafrost carbon for quantifying the permafrost carbon feedback within UKESM, the deep soil carbon in the permafrost region (below 1 m) was initialized using the observed soil carbon. There is now a slight drift in the soil carbon ( < 0.018 % decade −1 ), but the change in simulated soil carbon over the 20th century, when there is little climate change, is comparable to the original vertically discretized model and significantly larger than the drift.

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A quantitative model for integrating landscape evolution and soil formation

Cited by 117 publications

References 100 publications

A simple model for regolith formation by chemical weathering

A simple model for regolith formation by chemical weathering

Colluvial deposits as a possible weathering reservoir in uplifting mountains

A vertical representation of soil carbon in the JULES land surface scheme (vn4.3_permafrost) with a focus on permafrost regions

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