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Stream power

About: Stream power is a(n) research topic. Over the lifetime, 1135 publication(s) have been published within this topic receiving 51324 citation(s).
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Journal ArticleDOI
Abstract: The longitudinal profiles of bedrock channels are a major component of the relief structure of mountainous drainage basins and therefore limit the elevation of peaks and ridges. Further, bedrock channels communicate tectonic and climatic signals across the landscape, thus dictating, to first order, the dynamic response of mountainous landscapes to external forcings. We review and explore the stream-power erosion model in an effort to (1) elucidate its consequences in terms of large-scale topographic (fluvial) relief and its sensitivity to tectonic and climatic forcing, (2) derive a relationship for system response time to tectonic perturbations, (3) determine the sensitivity of model behavior to various model parameters, and (4) integrate the above to suggest useful guidelines for further study of bedrock channel systems and for future refinement of the streampower erosion law. Dimensional analysis reveals that the dynamic behavior of the stream-power erosion model is governed by a single nondimensional group that we term the uplift-erosion number, greatly reducing the number of variables that need to be considered in the sensitivity analysis. The degree of nonlinearity in the relationship between stream incision rate and channel gradient (slope exponent n) emerges as a fundamental unknown. The physics of the active erosion processes directly influence this nonlinearity, which is shown to dictate the relationship between the uplift-erosion number, the equilibrium stream channel gradient, and the total fluvial relief of mountain ranges. Similarly, the predicted response time to changes in rock uplift rate is shown to depend on climate, rock strength, and the magnitude of tectonic perturbation, with the slope exponent n controlling the degree of dependence on these various factors. For typical drainage basin geometries the response time is relatively insensitive to the size of the system. Work on the physics of bedrock erosion processes, their sensitivity to extreme floods, their transient responses to sudden changes in climate or uplift rate, and the scaling of local rock erosion studies to reach-scale modeling studies are most sorely needed.

1,569 citations

Journal ArticleDOI
Abstract: Floodplains are formed by a complex interaction of fluvial processes but their character and evolution is essentially the product of stream power and sediment character. The relation between a stream's ability to entrain and transport sediment and the erosional resistance of floodplain alluvium that forms the channel boundary provides the basis for a genetic classification of floodplains. Three classes are recognised: (1) high-energy non-cohesive; (2) medium-energy non-cohesive; and (3) low-energy cohesive floodplains. Thirteen derivative orders and suborders, ranging from confined, coarse-grained, non-cohesive floodplains in high-energy environments to unconfined fine-grained cohesive floodplains in low-energy environments, are defined on the basis of nine factors (mostly floodplain forming processes). These factors result in distinctive geomorphological features (such as scroll bars or extensive backswamps) that distinguish each floodplain type in terms of genesis and resulting morphology. Finally, it is proposed that, because floodplains are derivatives of the parent stream system, substantial environmental change will result in the predictable transformation of one floodplain type to another over time.

884 citations

Journal ArticleDOI
01 Dec 2001-Geology
Abstract: Recent theoretical investigations suggest that the rate of river incision into bedrock depends nonlinearly on sediment supply, challenging the common assumption that incision rate is simply proportional to stream power. Our measurements from laboratory abrasion mills support the hypothesis that sediment promotes erosion at low supply rates by providing tools for abrasion, but inhibits erosion at high supply rates by burying underlying bedrock beneath transient deposits. Maximum erosion rates occur at a critical level of coarse-grained sediment supply where the bedrock is only partially exposed. Fine-grained sediments provide poor abrasive tools for lowering bedrock river beds because they tend to travel in suspension. Experiments also reveal that rock resistance to fluvial erosion scales with the square of rock tensile strength. Our results suggest that spatial and temporal variations in the extent of bedrock exposure provide incising rivers with a previously unrecognized degree of freedom in adjusting to changes in rock uplift rate and climate. Furthermore, we conclude that the grain size distribution of sediment supplied by hillslopes to the channel network is a fundamental control on bedrock channel gradients and topographic relief.

678 citations

Journal ArticleDOI
01 May 2001-Geology
Abstract: Despite intensive research into the coupling between tectonics and surface processes, our ability to obtain quantitative information on the rates of tectonic processes from topography remains limited due primarily to a dearth of data with which to test and calibrate process rate laws. Here we develop a simple theory for the impact of spatially variable rock-uplift rate on the concavity of bedrock river profiles. Application of the analysis to the Siwalik Hills of central Nepal demonstrates that systematic differences in the concavity of channels in this region match the predictions of a stream power incision model and depend on the position and direction of the channel relative to gradients in the vertical component of deformation rate across an active fault-bend fold. Furthermore, calibration of model parameters from channel profiles argued to be in steady state with the current climatic and tectonic regime indicates that (1) the ratio of exponents on channel drainage area and slope ( m / n ) is ∼0.46, consistent with theoretical predictions; (2) the slope exponent is consistent with incision either linearly proportional to shear stress or unit stream power ( n = 0.66 or n = 1, respectively); and (3) the coefficient of erosion is within the range of previously published estimates (mean K = 4.3 × 10 −4 m 0.2 /yr). Application of these model parameters to other channels in the Siwalik Hills yields estimates of spatially variable erosion rates that mimic expected variations in rock-uplift rate across a fault-bend fold. Thus, the sensitivity of channel gradient to rock- uplift rate in this landscape allows us to derive quantitative estimates of spatial variations in erosion rate directly from topographic data.

659 citations

Journal ArticleDOI
Abstract: A review of existing literature reveals some disadvantages of using Shields diagram as the criterion for incipient motion of sediment particles on an alluvial bed. A new criterion based on average flow velocity, fall velocity, and shear velocity Reynolds number is proposed herein with the supporting data collected by different investigators. This new criterion is used to calculate the dimensionless critical unit stream power in a dimensionless unit stream power equation for sediment transport. The dimensionless unit stream power is the ratio of the time rate of potential energy expenditure per unit weight of water and the terminal fall velocity of the sediment. More than 1,000 sets of data from both laboratory flumes and natural streams published by different authors are used to support this dimensionless equation for sediment transport.

557 citations

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