ORCID Profile
0000-0003-0528-3815
Current Organisation
Australian National University
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Publisher: Wiley
Date: 04-03-2020
DOI: 10.1002/ECO.2199
Publisher: Routledge
Date: 07-02-2020
Publisher: American Geophysical Union (AGU)
Date: 29-06-2021
DOI: 10.1029/2020WR028127
Abstract: Microtopography (MT) can govern runoff dynamics as a net result of local heterogeneities in the flow paths and ponding. This in turn controls the development of the surface water layer that connects and flows downslope. It is therefore important to understand which microtopographic features affect runoff generation dynamics and its macroscopic—hillslope scale—hydrological signatures (e.g., hydrographs, runoff and infiltration volumes). In this study, we numerically solve 2D overland flow from a single rain pulse on 1,460 idealized hillslopes with different slopes and sinusoidal microtopographies and different infiltration capacities. We assess hydrodynamic distributions, hydrographs and hydrological indices to assess the effects of MT and infiltration on the (local) hydrodynamic and (larger scale) hydrologic responses in terms of surface runoff regimes. The results show that MT enhances infiltration and that infiltration and runoff depend in a strong non‐linear way on slope and the properties of MT. Three regimes of influence of MT were identified: one in which MT plays a negligible role but there is a high sensitivity to the infiltration capacity curve, a second regime in which hydrological partitioning is highly sensitive to MT and the infiltration capacity curve, and a third regime in which MT increases infiltration, but the response is insensitive to particular features, and more affected by the average slopes. The regimes are the product of the interplay between small (MT) and large scale (slope) properties. Furthermore, the results suggest that hydrological signatures can be interpreted and explained by the spatiotemporal variation of surface connectivity.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-18200
Abstract: & & & strong& T& /strong& & strong& h& /strong& & strong& e onset & /strong& & strong& and generation & /strong& & strong& of runoff& /strong& & strong& ,& /strong& & strong& and the overall rainfall-runoff transformation, & /strong& & strong& resulting in hillslope and catchment runoff response, & /strong& & strong& are controlled by multiple interacting small-scale processes. & /strong& & strong& Small scale features& /strong& & strong& such & /strong& & strong& as surface & /strong& & strong& microtopography & /strong& & strong& -small variations around the average & /strong& & strong& terrain & /strong& & strong& shape- can& /strong& & strong& govern large scale signatures of runoff & /strong& & strong& dynamics& /strong& & strong& . & /strong& & strong& This is the net result of l& /strong& & strong& ocal heterogeneities in the flow paths and ponding & /strong& & strong& which in turn control& /strong& & strong& the development of the surface water layer and how it connects and flows downslope. & /strong& & strong& It & /strong& & strong& is & /strong& & strong& therefo& /strong& & strong& re & /strong& & strong& rel& /strong& & strong& evant to understand which microtopographic features may play a governing role in runoff generation dynamics. Given that it is very difficult to assess such processes experimentally in the field, we turn to computational modelling to assess different features, hydrological conditions and the overall response. & /strong& & & & & & & & & & & strong& In this work, we numerically solve a physically-based surface water model & /strong& & strong& (based on the Zero-Intertia approximation of the shallow-water equations)& /strong& & strong& on a& /strong& & strong& n idealised& /strong& & strong& hillslope & /strong& & strong& domain, forced by a& /strong& & strong& single pulse of rain. & /strong& & strong& To explore different topographies and microtopographies, we model& /strong& & strong& 1460 surfaces, & /strong& & strong& based on 10 sloping planes & /strong& & strong& (fr& /strong& & strong& om & /strong& & strong& .1%& /strong& & strong& to & /strong& & strong& %& /strong& & strong& )& /strong& & strong& on which a sinusoidal microtopography of various litudes& /strong& & strong& (from & /strong& & strong& & /strong& & strong& to & /strong& & strong& & /strong& & strong& cm)& /strong& & strong& and wavelengths& /strong& & strong& (from & /strong& & strong& & /strong& & strong& to & /strong& & strong& & /strong& & strong& cm)& /strong& & strong& is overlaid.& /strong& & strong& In a previous proof-of-concept work, we showed how these microtopograhies have an impact on rainfall-runoff-infiltration partitioning & /strong& & strong& and generate different runoff regimes from disconnected flow to steady sheet flow& /strong& & strong& . In this contribution, & /strong& & strong& we extend our analysis to include a more realistic, time-dependent infiltration capacity, & /strong& & strong& and therefore explore the effects this has in the process of ponding and establishing surface flow connectivity. We & /strong& & strong& extend the number of surfaces & /strong& & strong& (within the same ranges) & /strong& & strong& to better observe the different runoff regimes. & /strong& & strong& We & /strong& & strong& quantitatively & /strong& & strong& assess the results mainly in terms of the increase in total infiltration in the presence of microtopography relative to a smooth plan& /strong& & strong& e& /strong& & strong& , & /strong& & strong& and qualitatively in terms of the generated & /strong& & strong& runoff regimes.& /strong& & & & & & & & & & & strong& The results show that microtopography& /strong& & strong& increase& /strong& & strong& s& /strong& & strong& total infiltration & /strong& & strong& (up to six times in our simulations)& /strong& & strong& over the whole domain relative to & /strong& & strong& a& /strong& & strong& smooth & /strong& & strong& lane and there is & /strong& & strong& a strong non-linear dependency & /strong& & strong& of infiltration and runoff & /strong& & strong& on slope and & /strong& & strong& on& /strong& & strong& the ratio of the characteristic wavelength and litude of microtopography. & /strong& & strong& Moreover, three characteristic regimes of influence of microtopography exist: one in which microtopography plays a negligible role, another in which microtopography increases infiltration, but the particular & /strong& & strong& microtopography & /strong& & strong& features are not very relevant, and one regime in which small changes in microtopography generate significant variations on infiltration. & /strong& & strong& Such regimes are the result of the interplay between small (microtopography) and large scale (slope) & /strong& & strong& system & /strong& & strong& features. & /strong& & strong& Finally, the results also show that & /strong& & strong& the time-dependent infiltration capacity can enhance the effect of microtopography on infiltration. From a modelling perspective, these results hint that neglecting microtopography and time-dependent infiltration in hydrological modelling can lead to an underestimation of infiltration and an overestimation of runoff. & /strong& & strong& The coupled analysis of spatial & /strong& & strong& hydrodynamics& /strong& & strong& and hydrological & /strong& & strong& signatures& /strong& & strong& suggests that the & /strong& & strong& latter & /strong& & strong& can be & /strong& & strong& interpret& /strong& & strong& e& /strong& & strong& d and & /strong& & strong& explained by the spatiotemporal variations triggered by surface connectivity. & /strong& & &
Publisher: DE GRUYTER
Date: 16-07-2013
Publisher: Informa UK Limited
Date: 05-2013
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-2494
Abstract: & & Rainfall is a complex, spatial and temporally variated process and one of the core inputs for hydrological and hydrodynamic modelling. Most rainfalls are known to be moving storms with varying directions and velocities. Storm movement is known to be an important influence on runoff generation, both affecting peak discharge and the shape of hydrographs. Therefore, exploring the extent rainfall dynamics affect runoff generation and consequently flooded areas, can be an asset in effective flood risk management.& & & & In this work, we study how storm movement (e.g. characterized by velocity and direction) can affect surface flow generation, water levels and flooded areas within a catchment. Moreover, the influence of rainfall temporal variability in correlation with storm movement is taken into account. This is achieved by means of numerical-based, spatially explicit surface flow simulations using the tool ProMaIDes (2021), a free software for risk-based evaluation of flood risk mitigation measures. The storm events are generated using a microcanonical random cascade model and further on trajected across the catchment area.& & & & The study area is the Kan river catchment located in the province of Tehran (Iran) with a total area of 836 km& #178 , which has experienced multiple flooding events in recent years. Due to its semi-arid climate, steep topography with narrow valleys, this area has high potential for flash flood occurrence as a result of high intensity precipitation.& & & & The results of this study show a range of possible magnitudes of influence of rainfall movement on the catchment& #180 s runoff response. The resulting flood maps highlight the importance of rainfall velocity and most importantly the direction of the movement in the estimation of flood events as well as their likelihood in catchment area. Moreover, its shown that the magnitude of influence of storm velocity and direction on discharge& strongly depends on the location within the river network which it is measured.& & & & ProMaIDes (2021): Protection Measures against Inundation Decision support. promaides.h2.de& &
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-10102
Abstract: & & The concept of local-scale interactions of spatially periodic vegetation patterns are well known in arid and semi-arid regions. The vegetation patterns are easily observable from aerial and satellite photography. Additionally, various mathematical models have been developed to reproduce the patterns observed in nature, aimed towards understanding the driving factors leading to pattern properties. Several studies exist attempting to analyse spatial properties of these patterns, their spatial distribution and their relationship to& topography and climate. However, there are limitations in how these studies provide spatially-distributed statistics, and on the specifics of vegetation patch and band geometries, making it difficult to compare to model predictions.& & & & & This study proposes& a new workflow (implemented in R) to measure geometric& characteristics of vegetation bands and patches. We use high-resolution satellite imagery as the base dataset. Color filters are used to binarise and identify in idual patches/bands of arbitrary irregular shapes. We then compute different geometrical properties, such as& patch-size, separation between them, orientation, among others. Additionally, the principal axes of each patch/band are identified, and used to measure characteristic lengths and widths, for which statistics are then computed, and can be represented in spatial subdomains to allow for spatial analysis at different scales. The strategy can also be easily applied to modelling results, thus facilitating comparison, and the algorithm is flexible enough to yield different forms of patterns and spatial extent.& & & & As a test case, we apply this workflow to a study site (11.05 N, 28.35 E) in Kordofan, south Sudan (a region previously reported and documented in the literature), using Google Earth Imagery as input. For this domain (3500 x 1400 m), the& results show that the length of the patches has a strong positive correlation with their width. Additionally, the length and the average nearest neighbor distance displayed a small positive correlation to the elevation. Using the available ALOS topography, the results also confirm that that 92% of the bands in our study area are oriented perpendicularly to the slope direction, as is expected from these systems.& & & & & This test is a first step into applying this workflow to a larger extend within Kordofan and other regions known to exhibit vegetation bands (tiger bush in wester Africa, Australia, Nevada) and perform extensive geometric and spatial analysis of the bands, as well as simulated banded systems obtained from numerical models.& & & & Keywords: Vegetation patterns, Self-organization, Tiger-bush, Geometric analysis, Oriented direction& &
Publisher: Oxford University Press
Date: 15-12-2022
DOI: 10.1093/OSO/9780198847182.001.0001
Abstract: This book explores the syntactic and semantic change of three types of constructions in the history of Spanish and Portuguese: (i) complex DPs with clausal adjunction ( el hecho de , o facto de ), (ii) complex prepositions/complementizers and complex connectives ( sin embargo de , sem embargo de so pena de, sob pena de ), and (iii) complex predicates containing light verbs ( dar consejo de, dar conselho de ). While these constructions are syntactically different, they are all clause-taking expressions containing a noun followed by the functional preposition de (“of”). This book is the first work to examine them together through a systematic comparative corpus study. This makes it possible to tease apart in idual from general changes and to focus on the chronological clustering of changes involving complex constructions in both languages. The development of these constructions has multiple causes related to the noun. Specifically, the reanalysis of the entire expression is affected both by the meaning of the noun and by changes in complementation patterns that affected nouns (as well as verbs and adjectives) in the 16th–17th centuries in both languages. By studying mechanisms of language change and their outcomes in two sister languages, the book addresses questions like: How do complex constructions evolve? How does the meaning of the noun change when considered in isolation and when compared to the meaning of the whole construction? How do syntactic categories change over time? Studies of closely related languages, which can reveal distinct developments occurring in parallel over time, provide a crucial test case for theories of language change.
Publisher: Informa UK Limited
Date: 14-10-2014
Publisher: The University of Kansas
Date: 2008
Publisher: Informa UK Limited
Date: 05-2013
Publisher: Informa UK Limited
Date: 02-01-2015
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-11905
Abstract: & & In arid environments, vegetation tends to self-organize into patches separated by bare soil. This is necessitated by the lack of water for sustaining a continuous vegetation cover and facilitated by the attraction of water from barren interpatch areas by the vegetation. This process is a positive feedback which introduces spatially heterogeneity into otherwise homogeneous environments, characterised by regular patterns. These patterns are typically considered to be periodic and distinguished on hand of their wavelength. Such patterns have so far been studied with numerical models which generate periodic patterns in homogeneous environments. However, environments are rarely homogeneous, as topography and soil-hydraulic properties vary in space. This raises the questions to which degree heterogeneity of vegetation is self-organized or imposed by the environment, and how environmental heterogeneity interacts with the self-organization process. In contrast to the persisting conceptual model of periodic patterns, natural vegetation exhibit a high degree of irregularity. Several studies have linked this irregularity to heterogeneity in the environment, but a comprehensive theory for analysing the irregularity has not yet been established. Furthermore remains the extend of irregularity unexplored on a global scale. To fill this gap, we, demonstrate empirically the global prevalence of irregularity in vegetation patterns and find that natural vegetation patterns are stochastic, rather than periodic. We then propose a stochastic framework to conceptually describe and measure the regularity, based on the spectral density of the patterns. In addition to the dominant wavelength, measuring the spatial scale, it reveals a novel parameter, measuring the regularity. The parameter is determined by the correlation structure and discriminates gradually between the limit cases of periodicity and white noise. Applied to natural and computer-generated patterns, we find that the former are highly irregular, while the latter are close to periodic. We reproduce the stochasticity of patterns with numerical models by introducing spatial heterogeneity of the model coefficients. We provide a fresh look at the nature of vegetations patterns and present a comprehensive theory for a more holistic understanding of self-organized systems.& & & & & img src=& quot ileStorageProxy.php?f=gnp.b390733f41e167285512461/sdaolpUECMynit/22UGE& app=m& a=0& c=abd147c2aca67c19a20b0a025d582dd3& ct=x& n=gnp.elif& d=1& quot alt=& quot & quot width=& quot & quot height=& quot & quot & & &
Publisher: John Benjamins Publishing Company
Date: 29-01-2018
Publisher: John Benjamins Publishing Company
Date: 2014
DOI: 10.1075/IHLL.1.06CAN
Publisher: Universitat Autonoma de Barcelona
Date: 15-09-2022
Abstract: N/A
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-5004
Abstract: & & Surface runoff (dis)connectivity manifests across scales, spawning from different spatial flow patterns, which are dominated by both topography (structural connectivity) and hydrodynamics (dynamic connectivity). How the connectivity builds and evolves throughout rainfall events is integrated into observable hydrological signatures (namely, hydrographs and water balance).& & & & & In this contribution we explore the connectivity properties of runoff generation processes across spatial scales. We revisit three case studies of runoff generation during rainfall, numerically simulated by solving shallow-water equations. This approach provides a full description of the hydrodynamic flow fields, allowing to study both the connectivity properties, as well as the domain-integrated hydrological signatures (namely, hydrographs) that build up in response to flow phenomena.& & & & & We discuss and link the runoff generation processes arising from (i) runoff generation at the plot scale (20 m2 at cm resolution) with explicit microtopographies, (ii) runoff generation at the hillslope or first-order catchment scale with overland and (ephemeral) rill flows in the H& #252 hnerwasser experimental catchment (4000 m2 at m resolution), and (iii) runoff generation at the catchment scale in the Lower Triangle catchment (15 km2 at m resolution).& & & & The detailed study of runoff generation dynamics highlights the needs to use time-evolving connectivity metrics, which are particularly useful to understand spatiotemporal model output. We computed the number of disconnected flooded clusters (and Euler characteristic) as the main connectivity metric.& & & & The results of the three different systems suggest similar qualitative behaviours of connectivity across scales, from plot to catchment scales, and therefore also offer the possible use of connectivity to understand how fluxes are re-scaled across the landscape, and as a multiscale indicator of hydrological function. The relationship between the connectivity response at a given scale (e.g., plot) and the hydrological signature observed at the next larger scale (e.g., hillslope) may lead into a hierarchical relationship of connectivities and signatures, in which the time-continuous nature of the connectivity signal may give rise to non-linear and threshold behaviours in the larger scale signature.& & & & & Additionally, in the context of assessing model quality, connectivity is a feature of the natural system which models (and modellers) should strive to ensure. In this sense, we argue that model formulations, meshing (including resolution/topology and preprocessing/smoothing of the terrain model) and parameterisations should be evaluated not only using integrated signatures (e.g., water balance, hydrographs) or point data (water depth, velocities) but also using (dis)connectivity metrics. In this way, it is possible to evaluate to which extent a model and its setup can simulate natural flow paths and landscape functions.& &
Publisher: Walter de Gruyter GmbH
Date: 27-05-2019
Abstract: This paper provides empirical evidence showing that the clause-taking nominals el hecho de (Spanish) and o facto de (Portuguese) are not reliable tests of factivity of predicates, as commonly assumed in the literature. Naturally occurring data from both languages show that these nominals are compatible with a wide range of predicates and that they occur in sentences with both factive and non-factive interpretations. Our findings contribute to the debate on the syntactic and semantic properties of clause-taking nominal constructions, clausal nominalization in Ibero-Romance, and to current research on the nature of factivity.
No related grants have been discovered for Manuel Delicado Cantero.