Transience of channel head locations following disturbance

Pires

et al. 2019

Sci Rep

Drainage basins are essential to Geohydrology and Biodiversity. Defining those regions in a simple, robust and efficient way is a constant challenge in Earth Science. Here, we introduce a model to delineate multiple drainage basins through an extension of the Invasion Percolation-Based Algorithm (IPBA). In order to prove the potential of our approach, we apply it to real and artificial datasets. We observe that the perimeter and area distributions of basins and anti-basins display long tails extending over several orders of magnitude and following approximately power-law behaviors. Moreover, the exponents of these power laws depend on spatial correlations and are invariant under the landscape orientation, not only for terrestrial, but lunar and martian landscapes. The terrestrial and martian results are statistically identical, which suggests that a hypothetical martian river would present similarity to the terrestrial rivers. Finally, we propose a theoretical value for the Hack’s exponent based on the fractal dimension of watersheds, γ = D/2. We measure γ = 0.54 ± 0.01 for Earth, which is close to our estimation of γ ≈ 0.55. Our study suggests that Hack’s law can have its origin purely in the maximum and minimum lines of the landscapes.

Section: Resultsmentioning

confidence: 99%

A universal approach for drainage basins

Pires

et al. 2019

Sci Rep

“…However, contributing areas for channel heads had mostly returned to prefire locations within four years of the fire (Figure 8, bottom). Wohl and Scott (2017) distinguished three populations of channel heads in the study area: (1) permanent channel heads on distinct hillslope concavities, with the channel head fixed in place by a persistent slope discontinuity such as a bedrock outcrop (the location of these channel heads was not affected by the fire); (2) transient channel heads on straight and convex hillslopes, which formed immediately after the fire but then completely disappeared within a few years as diffusive downslope movement of sediment and regrowth of vegetation obliterated the channel head; and (3) mobile channel heads, typically located on concave portions of the hillslopes, which moved upslope immediately after the fire but then gradually moved back downslope to a prefire location.…”

Section: The Role Of Disturbancementioning

confidence: 99%

The upstream extent of a river network : a review of scientific knowledge of channel heads

Wohl¹

2018

Self Cite

A river channel is a linear feature with definable bed and banks created by erosion of water concentrated into persistent flow paths. A river starts at the channel head, which is the upstream-most point of concentrated water flow and sediment transport between definable banks that are spatially continuous downslope. The locations of individual channel heads are difficult to predict because of hillslope-scale differences in gradient, infiltration capacity, porosity and permeability, and cohesion, each of which influences flow paths and erodibility of near-surface materials. Understanding the state of knowledge regarding the initiation point of channels can be useful in a management context when assessing what features on the landscape constitute river channels. Therefore, the primary objective of this report is to concisely summarize the existing state of scientific knowledge regarding where river channels and channel networks begin in the landscape. The report draws on published studies from diverse regions within the United States and around the world but focuses on research summarized in English. This report introduces terms, reviews the processes related to channel initiation in different landscape settings, discusses field and remote identification of channel heads, and outlines the research needs for channel-head identification and for improving channel delineation.

Earth Surf Processes Landf

“…Wohl and Scott (2017) report on short-term evolution of channel heads in the same burned area in Colorado examined by Sosa-Pérez and MacDonald (2017). Wohl and Scott (2017) report on short-term evolution of channel heads in the same burned area in Colorado examined by Sosa-Pérez and MacDonald (2017).…”

Section: Papers In the Themed Issuementioning

confidence: 99%

“…As downslope movements of water and sediment change following fire, the geomorphic transition from diffusive movement to concentrated, channelized flow that occurs at a channel head can also change location. Wohl and Scott (2017) report on short-term evolution of channel heads in the same burned area in Colorado examined by Sosa-Pérez and MacDonald (2017). Hillslope surveys immediately following a 2012 wildfire indicated that channel heads moved upslope, resulting in a decrease in median contributing drainage area of two orders of magnitude relative to channel heads in unburned areas.…”

Section: Papers In the Themed Issuementioning

confidence: 99%

“…Brogan et al (2017) examine channel changes through time in response to convective and longer-duration, lower intensity mesoscale rainfall. Working in the same, well-studied Colorado field site with the 2012 fire (see Wagner et al, 2015, Sosa-Pérez and MacDonald, 2017, and Wohl and Scott, 2017, Brogan et al document channel responses in the 15.5 km 2 Skin Gulch drainage. A convective storm immediately after the fire created estimated peak unit discharges of 28 m 3 /s/km 2 and substantial channel aggradation.…”

Section: Papers In the Themed Issuementioning

confidence: 99%

See 1 more Smart Citation

Introduction to the themed issue: Wildfire and Geomorphic Systems

Wohl

2018

Self Cite

Wildfires alter fluxes of water, sediment, solutes, and organic matter in ways that can be transient or persistent. Alterations in material flux then impact geomorphic processes and landforms in a manner that can also be transient or persistent and that can involve complex response. This themed issue includes papers that document distinctive geomorphic responses in the upland and channel components of forested landscapes in southern Europe, northern Australia, and the western United States. Among the themes that emerge from the collected papers are: (i) the importance of ongoing technological developments, including real‐time instrumentation, ground‐based and aerial remote sensing, isotopic ratios, and numerical models of landscape processes, for documenting and predicting fire‐related geomorphic processes; and (ii) the great uncertainties about future landscape change in a global environment of rapidly changing climate and growing human populations that encroach onto remaining wildlands in fire‐susceptible regions. Copyright © 2017 John Wiley & Sons, Ltd.