Topographic Analysis Research Articles

Impact of river capture on erosion rates and offshore sedimentation revealed by geological and in situ 10Be cosmogenic data (Corsica, western Mediterranean)

Quantitative analysis of fluvial topography and sediment yield changes are often independently used to detect major river capture events and episodes of drainage reorganization. Here we use a unique set of geological and in situ 10Be cosmogenic data from Corsica, Western Mediterranean, to provide evidence of major river capture events affecting the former Paleo-Ostriconi river catchment during the Pliocene, and to illustrate how the landscape of Corsica is still reacting to the disequilibrium caused by the late Miocene uplift of Alpine Corsica. We found that ∼1280 km2 of basin area originally draining towards the Ligurian Sea were abruptly connected to the Tyrrhenian Sea by the capturing Tavignano and Golo rivers, which led to the formation of a large Pliocene-Quaternary submarine fan offshore the Tyrrhenian coast. The increased sediment yield towards the Tyrrhenian margin after river capture in the Pliocene was three times greater than the average sediment yield in the same source-to-sink system during the Holocene (410±100 t·km−2·a−1 vs ∼131±8 t·km−2·a−1) and greater magnitude than any subsequent peaks in sediment yield during late Pleistocene glaciations. 10Be-derived denudation rates reveal that focused erosion still affects retreating knickpoints near the sites of former river capture in central Corsica, suggesting persistence of landscape disequilibrium for several millions of years. Our results demonstrate the potentially large impact of river capture on the stratigraphic record and highlight the importance of full consideration of landscape response times to onshore disturbances for any reliable interpretation of the offshore sedimentary archive.

Trivalent Cations Slow Electron Transfer to Macrocyclic Heterobimetallic Complexes.

Incorporation of secondary redox-inactive cations into heterobimetallic complexes is an attractive strategy for modulation of metal-centered redox chemistry, but quantification of the consequences of incorporating strongly Lewis acidic trivalent cations has received little attention. Here, a family of seven heterobimetallic complexes that pair a redox-active nickel center with La3+, Y3+, Lu3+, Sr2+, Ca2+, K+, and Na+ (in the form of their triflate salts) have been prepared on a heteroditopic ligand platform to understand how chemical behavior varies across the comprehensive series. Structural data from X-ray diffraction analysis demonstrate that the positions adopted by the secondary cations in the crown-ether-like site of the ligand relative to nickel are dependent primarily on the secondary cations' ionic radii and that the triflate counteranions are bound to the cations in all cases. Electrochemical data, in concert with electron paramagnetic resonance studies, show that nickel(II)/nickel(I) redox is modulated by the secondary metals; the heterogeneous electron-transfer rate is diminished for the derivatives incorporating trivalent metals, an effect that is dependent on steric crowding about the nickel metal center and that was quantified here with a topographical free-volume analysis. As related analyses carried out here on previously reported systems bear out similar relationships, we conclude that the placement and identity of both the secondary metal cations and their associated counteranions can afford unique changes in the (electro)chemical behavior of heterobimetallic species.

Analysis of Choriocapillaris Reperfusion Topography following Faricimab Treatment for Neovascular Age-Related Macular Degeneration in Non-Treatment-Naïve Patients.

To assess changes in choriocapillaris (CC) vascular density surrounding macular neovascularization (MNV) in age-related macular degeneration (AMD) when transitioning from various anti-VEGF treatments to faricimab, using optical coherence tomography angiography (OCTA). 25 eyes of 22 individuals who underwent intravitreal faricimab injections for neovascular AMD with type 1 MNV were included. OCTA images were obtained prior to (T0), after one (T1), and after three faricimab injections (T2); Noteworthy changes occurred in the first ring at T2 in comparison to T0. The percentage of CC flow deficit (FD%), FD average area (FDa), and FD number (FDn) in 5 rings (R1-R5) surrounding the dark halo around the MNV were calculated. A reduction in FD% at T2 compared to T0 (50.5 ± 10.2% at T0, 46.4 ± 10.6% at T2; p = 0.020) was seen, indicating CC reperfusion. Additionally, we observed a reduction in the average FDa (140.2 ± 172.1% at T0, 93.7 ± 101.8% at T2; p = 0.029). Our study highlights an FD% after three consecutive faricimab injections. The most pronounced effect was observed in the first ring, directly adjacent to the dark halo, suggesting a partial CC reperfusion surrounding the MNV, potentially indicating disease regression.

MORPHOLOGY AND MORPHOMETRY CHARACTERISTIC OF RAYA WATERSHED

The study of watershed morphology and land use patterns significantly affects hydrological processes and runoff coefficients, highlighting the quantitative nature of watershed characteristics. The Raya Watershed in West Kalimantan influences local communities and aims to enhance understanding of its physical attributes and hydrological dynamics through detailed analysis of topography, soil composition, land use, and river networks. Findings inform watershed management and conservation strategies. The analysis of the Raya Watershed, spanning 29,982.96 hectares (87.34% of total area) with elevations below 100 meters, reveals flat terrain vulnerable to flooding, particularly in low-lying or sea-level regions, exacerbated by limited natural drainage. Lower elevations support crucial wetland and floodplain ecosystems. Hydrological disruptions from land use changes and climate fluctuations can harm biodiversity and water quality. Effective land use planning is vital to address flood risk and environmental concerns, mitigating impacts like property damage and population displacement. Soil-type mapping informs conservation efforts, ensuring ecosystem resilience. Sustainable land management practices, guided by watershed characteristics like drain density and stream frequency, are essential to mitigate biodiversity loss and ecological imbalances.

Effect of different surface roughening treatment on polyether ether ketone and acrylic resin bonding: A pilot study.

As polyether ether ketone (PEEK) is a relatively new material in dentistry, its bonding properties with regard to dental acrylic base materials are not fully known. To ensure the long-term success of removable dentures with a PEEK framework, the base materials must be well bonded to each other. The study aimed to investigate the effects of different kinds of surface roughening treatment on PEEK and acrylic resin bonding. Eighty PEEK specimens (N = 80) were randomly divided into 5 groups (n = 16 per group) and subjected to various surface roughening treatment (control, grinding, sandblasting, tribochemical silica coating (CoJet), and sulfuric acid etching). Heat-polymerized acrylic resin was applied to the treated surfaces of the PEEK specimens. The shear bond strength (SBS) test, environmental scanning electron microscopy (ESEM) analysis and three-dimensional (3D) surface topography analysis were performed. The statistical analysis of the data was conducted using the analysis of variance (ANOVA) and Tukey's multiple comparison test. The one-way ANOVA showed significant differences in the SBS values between the groups (p = 0.001). Sandblasting, tribochemical silica coating and sulfuric acid etching resulted in high SBS values (p = 0.001). The highest SBS values were observed in the sulfuric acid etching group (8.83 ±3.63 MPa), while the lowest SBS values were observed in the control group (3.33 ±2.50 MPa). The additional roughening treatment applied to the PEEK surface increases the bond strength with heat-polymerized acrylic resin.

Theoretical Investigation on Dialumenes toward Dihydrogen Activation: Mechanism and Ligand Effect.

Herein, we report a computation study based on the density functional theory calculations to understand the mechanism and ligand effect of the base-stabilized dialumenes toward dihydrogen activation. Among all of the examined modes of dihydrogen activation using the base-stabilized dialumene, we found that the concerted 1,2-hydrogenation of the Al═Al double bond is kinetically more preferable. The concerted 1,2-hydrogenation of the Al═Al double bond adopts an electron-transfer model with certain asynchrony. That is, the initial electron donation from the H-H σ bonding orbital to the empty 3p orbital of the Al1 center is followed by the backdonation from the lone pair electron of the Al2 center to the H-H σ antibonding orbital. Combined with the energy decomposition analysis on the transition states of the concerted 1,2-hydrogenation of the Al═Al double bond and the topographic steric mapping analysis on the free dialumenes, we ascribe the higher reactivity of the aryl-substituted dialumene over the silyl-substituted analogue in dihydrogen activation to the stronger electron-withdrawing effect of the aryl group, which not only increases the flexibility of the Al═Al double bond but also enhances the Lewis acidity of the Al═Al core. Consequently, the aryl-substituted dialumene fragment suffers less geometric deformation, and the orbital interactions between the dialumene and dihydrogen moieties are more attractive during the 1,2-hydrogenation process. Moreover, our calculations also predict that the Al═Al double bond has a good tolerance with the stronger electron-withdrawing group (-CF3) and the weaker σ-donating N-heterocyclic carbene (NHC) analogue (e.g., triazol carbene and NHSi). The reactivity of the dialumene in dihydrogen activation can be further improved by introducing these groups as the supporting ligand and the stabilizing base on the Al═Al core, respectively.

A Middle Palaeolithic incised bear bone from the Dziadowa Skała Cave, Poland: the oldest marked object north of the Carpathian Mountains

A fragment of an ursid radius with seventeen incisions (one of them incomplete) was excavated in the 1950s in the Dziadowa Skała Cave in the Częstochowa Upland in southern Poland from a deposit with faunal remains from the Eemian (ca 130–115 kyr). This object has been cited as the earliest evidence of Neanderthal cognitive abilities in the region, but it has been never studied in detail. The artefact has now been re-examined using microscopy and X-ray computed tomography. For this study we revised the determination of the bone and studied the morphology and metric parameters of the incisions (length, width, depth and opening angle). We also used experiments, statistical analysis and an analysis of the incisions' topography to establish the techniques behind their manufacture. The obtained results show that the bone was marked using a retouched stone tool, and that the incisions were produced during a single episode by a right-handed individual using repeated unidirectional movements of the tools’ cutting edge. The incisions are evidently an effect of a deliberate action, not a side-effect of some practical activity. The bear radius from Dziadowa Skała is thus yet another piece of evidence for the emergence of symbolic culture, evolved by hominins in Africa and Eurasia, and represents the oldest example of marked bone north of the Carpathian Mountains.

Implications of MOLA topography on the presence of liquid water under the south polar cap of Mars

The existence of liquid water at the base of the south polar layered deposits (SPLD) on Mars has been proposed on the basis of radar data, but dry interpretations have been advanced as well. Here, we consider topography of the SPLD surface above the location of hypothesized water using individual altimetry tracks rather than gridded or interpolated data. Liquid water could create negative surface relief through drainage events and subsequent collapse, or positive surface relief through ice expansion. We find meters of positive topographic relief relative to the surrounding region, consistent with thermal expansion of the ice column from the added geothermal heat that would be required to maintain liquid water at the SPLD base. However, topographic analysis of randomly chosen areas throughout the SPLD suggest that positive topographic relief of this amplitude has a 20% chance of occurring through other processes or statistical noise. Therefore, we conclude that both wet and dry interpretations of the radar data remain viable.

Maxillary Sinus Floor Elevation and Simultaneous Implant Installation via Osseodensification Drills: A Retrospective Analysis of Bone Gain in 72 Patients Followed for 6 Months.

Background/Objectives: The aim of this retrospective study was to radiographically evaluate the endo-sinus bone gain (ESBG) following osseodensification procedures using CBCT and compare the results to more conventional sinus lifting techniques. Methods: A total of 72 patients underwent crestal sinus floor elevation procedures and were provided with 102 implants with a sand-blasted and acid-etched surface with microthreads (Medentika® Microcone Implants, Hugelsheim, Germany). Patients were divided into two groups; the osseodensification group (OD; n = 36) and the osseodensified augmentation group (ODA; n = 36). Results: The mean residual bone height (RBH) was 5.71 (1.77) and 4.30 (0.94) mm in the OD and ODA groups, respectively. An ESBG of 3.45 (1.18) and 5.74 (1.31) mm was observed in the OD and ODA groups, respectively, and as compared to the baseline RBH, the ESBG was statistically significant in both groups after 6 months (p < 0.001). Conclusions: Within the limits of this retrospective study, crestal sinus lifting with the osseodensification technique seems to be a fast, effective, and safe method. Longer follow-up studies with full intrasinus bone topography and structure analyses are needed to prove the success rate of endo-sinus bone gain.

Effect of Macro Fibers on the Permeability and Crack Surface Topography of Layered Fiber Reinforced Concrete.

This paper describes the effects of macro fibers on permeability and crack surface topography of layered fiber-reinforced concrete (FRC) specimens with different layering ratios under uniaxial tensile load. The crack permeability of layered FRC specimens is investigated by a self-designed permeability setup. The topographical analysis of crack surfaces is investigated by a custom-designed laser scanning setup. The results show that when the fiber volume content and layering ratio of the FRC layer are constant, the tensile toughness of layered FRC specimens depends on the proportion of steel fiber in macro fibers, and with an increase in the proportion of steel fiber, the tensile toughness of layered FRC specimens increases. For the layered FRC specimens, the crack permeability is much lower than that of the normal concrete (NC) specimen. A significant positive synergistic effect on crack impermeability can be achieved by the combination of steel fiber and polypropylene fiber in the SF80PP2.3 specimen. The crack surface roughness parameter (Rn) values of the NC layer in layered FRC specimens are all higher than those of the NC specimen, and the crack surface Rn of the FRC layer in layered FRC specimens is higher than that of the unlayered FRC specimens. This can effectively increase the head loss of cracks and reduce the crack permeability of layered FRC specimens.

Core/Shell-Like Localized Emission at Atomically Thin Semiconductor-Au Interface.

Localized emission in atomically thin semiconductors has sparked significant interest as single-photon sources. Despite comprehensive studies into the correlation between localized strain and exciton emission, the impacts of charge transfer on nanobubble emission remains elusive. Here, we report the observation of core/shell-like localized emission from monolayer WSe2 nanobubbles at room temperature through near-field studies. By altering the electronic junction between monolayer WSe2 and the Au substrate, one can effectively adjust the semiconductor to metal junction from a Schottky to an Ohmic junction. Through concurrent analysis of topography, potential, tip-enhanced photoluminescence, and a piezo response force microscope, we attribute the core/shell-like emissions to strong piezoelectric potential aided by induced polarity at the WSe2-Au Schottky interface which results in spatial confinement of the excitons. Our findings present a new approach for manipulating charge confinement and engineering localized emission within atomically thin semiconductor nanobubbles. These insights hold implications for advancing the nano and quantum photonics with low-dimensional semiconductors.

Unfolding rotational tectonics and topographic evolution from localized verses diffuse plate boundary counterparts

We present a kinematic model developed from geodetic observations, topography analysis and analogue tectonic modelling results, which reveals a striking similarity between the rotational tectonic settings of the Gakkel Ridge-Chersky Range system in the Arctic, and the Central Indian Tectonic Zone within the Indian subcontinent. A crucial aspect of large-scale extensional rift systems is the gradual variation of extension along the rift axis, due to plate rotation about a Euler pole, which may lead to contraction on the opposite side of the Euler pole to form a rotational tectonic system. Our geodetic and topographic analysis, combined with the reanalysis of analogue tectonic modelling results demonstrates such rotational tectonic plate motion in both the Arctic and Indian case. However, the plate boundary between the North American and Eurasian Plates as represented by the Arctic Gakkel Ridge-Chersky Range system is strongly localized, whereas the Central Indian Tectonic Zone that separates the North and South India Plates involves diffuse deformation instead. Furthermore, in both the Arctic and Central Indian we find that the relative Euler rotation pole is located near an indenter-like feature, which possibly controls the present-day rotational tectonics and contrasting topography on opposite sides of the Euler pole.

Rapid Deposition of the Biomimetic Hydroxyapatite-Polydopamine-Amino Acid Composite Layers onto the Natural Enamel.

In this work, we developed a technology that enables rapid deposition of biomimetic composite films onto natural enamel slices (known as biotemplates). These films are composed of polydopamine (PDA) and nanocrystalline carbonate-substituted hydroxyapatite (nano-cHAp) that have been functionalized with amino acid l-Arginine. We utilized atomic force microscopy (AFM) and scattering scanning near-field optical microscopy (s-SNOM) combined with infrared (IR) synchrotron to achieve nanoscale spatial resolution for both IR absorption and topography analyses. This combined analytical modality allowed us to understand how morphology connects to local changes in the chemical environment on the biotemplate surface during the deposition of the bioinspired coating. Our findings revealed that when using the proposed technology and after the deposition of the first PDA layer, the film formed on the enamel surface nearly covers the entire surface of the specimen whose thickness is larger on the surface of the emerging enamel prisms. Calculation of the crystallinity index for the biomimetic layer showed a multiple increase compared with natural enamel. This indicates regular and dense aggregation of nano-cHAp into larger crystals, imitating the morphology of natural enamel rods. The microhardness of the formed PDA-based biomimetic layer mineralized with nano-cHAp functionalized with amino acid l-Arginine deposited on natural enamel was practically the same as that of natural enamel. The characterization of nano-cHAp-amino acid-PDA layers using IR and Raman microspectroscopy showed that l-arginine acts as a conjunction agent in the formation of mineralized biomimetic composite coatings. The uniformity of the mechanisms of PDA layer formation under different deposition conditions and substrate types allows for the formation of coatings regardless of the macro- and micromorphology of the template. Therefore, the results obtained in this work have a high potential for future clinical applications in dental practice.

Neural tracking of natural speech in children in relation to their receptive speech abilities

Receptive speech is the ability to understand speech addressed to a person. It is a crucial process for a child’s cognitive development. We examine the relationship between receptive speech and neural tracking of natural speech in 52 children aged 3–8 years to infer the neurophysiological mechanisms underlying speech development. We registered a 32-channel electroencephalogram (EEG) while children listened to narrative audio stories. The temporal response function (TRF) approach was used to study neural tracking features at acoustic and semantic levels. We found a strong positive correlation between the TRF prediction accuracy values that demonstrate the magnitude of neural tracking, and receptive speech abilities measured by the Preschool Language Scales (PLS-5). Topographic analysis of these correlations showed significant clusters of EEG channels in the right temporal region for acoustic tracking, and in the left fronto-central and right parieto-occipital regions for semantic tracking. We assume that these results reflect the development of the brain systems necessary for speech comprehension. To sum up, we suggest that the TRF measures are easy-to-assess neurophysiological markers of receptive speech development in children.

Studying Patterns of Rainfall and Topographical Clustering for Kingdom of Bahrain: An Application of Big Data

Rainfall is an important aspect for urban planners, especially for professionals related to highway design. This study was aimed at studying the patterns of rainfall in Kingdom of Bahrain using cluster analysis with topographical data. The rainfall data was collected from the website meteorological directorate of ministry of transportation and telecommunication of Bahrain, which consisted of approximately 14000 days, thus referred to as big data. K-means clustering was used to identify the patterns. Moreover, Geographic Information System (GIS) was used for topographical clustering of elevation map of Bahrain. This was done to identify the areas which should receive more attention with regards to drainage due to the topography of Bahrain. The results of this study showed that the time periods which receive comparatively heavier rainfall are around January while those with significantly lower rainfall are during May and October. The topographical analysis showed that the northern parts of the country are supposed to be paid more attention to avoid flooding and, consequently, damage to infrastructure. Moreover, results of the study could be used by the urban and transportation planners in Bahrain for design of efficient drainage resulting in economic benefits to the society.

Atomic Force Microscopy beyond Topography: Chemical Sensing of 2D Material Surfaces through Adhesion Measurements.

Developing new functionalities of two-dimensional materials (2Dms) can be achieved by their chemical modification with a broad spectrum of molecules. This functionalization is commonly studied by using spectroscopies such as Raman, IR, or XPS, but the detection limit is a common problem. In addition, these methods lack detailed spatial resolution and cannot provide information about the homogeneity of the coating. Atomic force microscopy (AFM), on the other hand, allows the study of 2Dms on the nanoscale with excellent lateral resolution. AFM has been extensively used for topographic analysis; however, it is also a powerful tool for evaluating other properties far beyond topography such as mechanical ones. Therefore, herein, we show how AFM adhesion mapping of transition metal chalcogenide 2Dms (i.e., MnPS3 and MoS2) permits a close inspection of the surface chemical properties. Moreover, the analysis of adhesion as relative values allows a simple and robust strategy to distinguish between bare and functionalized layers and significantly improves the reproducibility between measurements. Remarkably, it is also confirmed by statistical analysis that adhesion values do not depend on the thickness of the layers, proving that they are related only to the most superficial part of the materials. In addition, we have implemented an unsupervised classification method using k-means clustering, an artificial intelligence-based algorithm, to automatically classify samples based on adhesion values. These results demonstrate the potential of simple adhesion AFM measurements to inspect the chemical nature of 2Dms and may have implications for the broad scientific community working in the field.

Topographic Radioanatomical Analysis of the Singular Canal: Computed Tomography Study

Purpose: The singular canal (SC) is where the singular nerve, a branch of the inferior vestibular nerve, which carries afferent information from the posterior semicircular canal (PSCC), passes and is important in the surgical approach of the presigmoid retrolabyrinthine. This study was carried out to evaluate the visibility of the SC on standard computed tomography (CT) images, its distance to the surrounding structures, and to investigate the variations of its anatomy and its relationship with the meatus acusticus internus. Materials and Methods: The study was carried out retrospectively using images of 194 temporal bones on temporal bone CT scans of 44 men and 53 women aged 18–65. In the study, various measurements were made, especially the presence of the SC, its length, its angle with the internal acoustic canal (IAC), and the distance between the internal acoustic pore (IAP) and the singular foramen. In addition, the presence of the high jugular bulb and PSCC dehiscence images were investigated. Results: The SC was detected in 85.1% of the analyzed images. The mean canal length was 3.93 ± 1.22 mm, the angle between the SC and the IAC was 22.68° ±3.60°, and the distance between the SC and the IAP was 7.70 ± 0.83 mm. While no difference was found between the sides, it was determined that the length and diameter of the SC did not differ according to gender. Conclusion: Detailed morphometric analysis of the SC and a thorough understanding of its relationship with the IAC, vestibulum, and PSCC will help to accurately define the posterior and lateral borders of the dissection for this region.

Comprehensive material study of Ge grown by aspect ratio trapping on Si substrate

High-quality monolithic Ge-on-Si is sought for CMOS-compatible optoelectronic devices. We examine the structural characteristics of Ge-on-Si grown by the aspect ratio trapping (ART) method on a SiO2/Si(001) template in pre-patterned holes. Transmission electron microscopy and surface topography analysis revealed high-quality Ge islands overgrown from the ART holes in SiO2. The superior crystal quality of Ge ART growth was also confirmed by comparing x-ray diffraction (XRD) data of Ge ART and Ge planar epilayer samples. The XRD and micro-Raman data additionally show a small residual strain in the islands which vanishes by reducing the hole diameter from 280 nm to 180 nm, while leading to only a minor increase in the crystallographic inclinations of the Ge islands from 0.34 deg to 0.54 deg. With finite element method simulations, we find that the small residual strain in Ge originates during the cool-down from growth to room temperature because of thermal expansion coefficient mismatch between Ge and SiO2. A tensile force develops along the [001] axis of the Ge pillar whose faster shrinkage to the room temperature volume is restricted by the oversized surface island.

Continuity, Resilience, and Change in Rural Settlement Patterns from the Roman to Islamic Period in the Sicani Mountains (Central-Western Sicily)

This study aims to analyze the dynamics of change in settlement models from the Roman, late antique, and Byzantine periods, focusing on how these transformations influenced the formation of Islamic societies in the rural landscapes of western Sicily. The study is centered around the territory of Corleone in the Sicani Mountains (central-western Sicily). This region, strategically located between the significant cities of Palermo on the Tyrrhenian Sea and Agrigento on the Strait of Sicily, has been pivotal in the communication network spanning from the Roman era to the Middle Ages and beyond. The area has been subject to extensive surveys and excavations, revealing diverse dynamics of continuity, resilience, and innovation in settlement patterns from the Roman to the Islamic periods. Beyond presenting the results of archaeological fieldwork, this study employs GIS-based spatial and statistical analyses and utilizes a range of topographic (elevation, slope, aspect, topographic position index (TPI), and distance to water sources) and ecological factors (vegetation series). These analyses aim to assess the evolving relationships and site positioning within the territory over time. Combining archaeological data with topographic and ecological landscape analysis, this integrated approach elucidates the complex transition dynamics from the Roman settlement system to the Islamic age’s landscape formation in western Sicily’s rural areas. The study thereby contributes to a deeper understanding of the intricate interplay between historical developments and environmental factors in shaping rural settlement patterns.

Limits to knickzone retreat and bedrock river incision on the Hawaiian islands

AbstractA knickzone is defined as a waterfall or an oversteepened fluvial reach encompassing a series of waterfalls. Knickzones are remarkable landforms in that they may represent diametrically opposed conditions: either rapid upstream propagation of base‐level fall or a condition of stability and stalled response to base‐level fall. Knickzones on the Hawaiian islands exhibit evidence of both behaviours, and in this study, we explore whether this dichotomy can be explained by a threshold stream power for river incision. Topographic analysis shows that the transition between fluvial hanging valleys, where no measurable upstream retreat from the stream junction or coastline has occurred, and knickzones that have retreated or formed upstream of their outlet can be defined by a range of catchment sizes from ~0.5 to 6 km2. This transition is present on all volcanoes in our analysis regardless of significant base‐level fall, and there is no clear trend of drainage area above knickzones with volcano age. To explain these observations, we hypothesize that knickzones form or stabilize where maximum unit stream power ( ) does not exceed the critical unit stream power required to incise bedrock . Using estimates of a maximum possible flood discharge as a function of drainage area to calculate , we show that drainage areas above knickzones are well described by the theoretical prediction that incision stalls when , where falls in a narrow range from 14 to 40 kW/m2. Furthermore, we demonstrate that knickzone positions are largely insensitive to mean climate conditions, likely reflecting the fact that extreme flood events are either insensitive or inversely correlated with mean annual rainfall.