@misc{AlmawazrehCaviedesVoulliemeHinz, author = {Almawazreh, Albara and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Solute dissipation regimes and rates controlled by soil evaporation and rainfall variability in heterogeneous soils}, series = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, journal = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, address = {Katlenburg-Lindau}, abstract = {Reactive solute leaching from the top soil has received wide attention as it relates to major environmental challenges like groundwater and river water pollution by leached reactive solutes such as agricultural pesticides or biochemical pollutants. Adequate understanding of how fast, when and how such solutes and possible contaminants are leached from the top soil is necessary to enhance agricultural practice, pollution risk assessment and overall water quality management. Many empirical studies have been carried on the subject, with varied their approaches and complexity, and have been carried out under different site and atmospheric conditions. Some ofsuch studies argue that properties of soils and solutes are dominant for the leaching process, while others emphasizeatmospheric drivers as a main trigger for preferential flow. Long residence times have also been observed, with solutes lingering in the soils long after initially introduced and after experiencing rainfall events. Modelling and analytical studies have been put forward to better explain these behaviours, but often neglecting some of of the sources of complexity (such as preferential flow and soil heterogeneity) or with simplified modelling strategies. In this work, we study reactive solute dissipation processes in a soil column with a contaminated top soil layer in response to rainfall events. To cope with a heterogeneous soil structure, within an intermediate-complexity and physically-based framework, we solve Richards equation together with a mobile-immobile soil model together with a non-equilibrium advection-diffusion reaction model in Hydrus1D. We perform an extensive analysis of the sensitivity of solute dissipation rates from the top soil in response to all permutations of a parameter space comprised of soil properties (immobile fraction, mobile-immobile mass transfer coefficient), solute properties (decay coefficient, adsorption coefficient), rainfall parameters (total precipitation, duration, frequency) and the presence or absence of evaporation. Results are assessed in terms of the resulting solute dissipation curves and are fitted to exponential decay curves for comparison purposes. The results show that different solute dissipation regimes exist in response to the dominant physical process under a particular set of conditions. We identify three dissipation regimes which exhibit characteristic time scales and dissipation curve shapes: an advection dominated regime occurring under particular rainfall conditions, an evaporation dominated regime occurring under low rainfall volume and intensity and a decay-dominated regime exists, in which the bio- or chemical- decay rate of the substance is large and therefore dominant. Our results also provide further evidence and rationale for long residence times (which have been previously noted in the literature) in the top soil under preferential flow conditions, as the complex interactions between different processes may favour at mobilisation or immobilisation of the solute, which can be related to the characteristic shapes of the dissipation curves and in turn the regimes. The results allow a better understanding of the controlling processes and the related parameters interactions that dominate each regime. The thorough sensitivity analysis shows that, within those regimes, certain properties have higher weight and respectively more attention should be given when investigating them in comprehensive leaching risk assessment.}, language = {en} } @misc{BrueckRojasCaviedesVoulliemeetal., author = {Br{\"u}ck, Yasemine and Rojas, Pedro and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Processing of aerial images to detect vegetation cover and evaluate transient vegetation patch characteristics of H{\"u}hnerwasser catchment}, series = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, journal = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, address = {Katlenburg-Lindau}, abstract = {The artificial catchment "H{\"u}hnerwasser" was built in a post-mining landscape, as a field experiment to observe and monitor early-development ecosystems at first catchment scale. As vegetation is a key driver of hydrological catchment behavior, spatial distribution and temporal dynamics of vegetation affects water redistribution from plot to catchment scale. In the context of early ecosystem development, quantifying changes in vegetation structures is an obvious indicator for state transitions. The first years of ecosystem development at the H{\"u}hnerwasser catchment showed rapidly increasing complexity of emerging structures associated with rising vegetation cover and increasing number of plant species. This work will focus on characterizing vegetation cover using aerial images aiming to describe spatial structures and how those evolve in time. The early stages are especially of interest. The structure is therefore characterized by the area of the catchment covered by vegetation, the number of vegetation patches, the mean and maximum patch size and a form factor (area of patch divided by its perimeter). Aerial images with a resolution at cm scale were taken once per year from 2007 to 2018. Binary maps are generated by setting thresholds for red, green and blue channels to differentiate between vegetation cover and bare soil. To evaluate the consistency of the binary images of each channel these images were stacked and compared. The performance of the method was tested by using a set of combinations of thresholds and a comparison with manual mapping of vegetation cover at an image subset was made. The blue channel seems to be very sensitive to detect vegetation and a better differentiation of vegetation and dark/wet soil can be achieved by setting the thresholds of the channels in a specific order. The structures derived by the classification into vegetated and bare soil are more important in the early years of ecosystem development. In those years (2007 to 2011) the most changes took place. As time advances vegetation became less patchy and other characteristics need to be implemented to describe the vegetation cover, taking into account different plant functional types.}, language = {en} } @misc{CaviedesVoulliemeHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Transient trajectories in vegetation patterns spawning from non-equilibrium initial conditions and singular perturbations}, series = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, journal = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, address = {Katlenburg-Lindau}, abstract = {Vegetation self-organisation in water-limited ecosystems in semi-arid climates has been extensively studied by means of numerical simulation using a set of different reaction-diffusion-equations. Most of such models and studies have been concerned with the long-term steady ecohydrological steady states on domains with periodic boundary conditions and forced by steady rainfall. A vast majority of the modelling literature on vegetation self-organisation exists around near-equilibrium conditions. One of the clearest examples of this is that most of the published numerical results have been obtained by evolving near-equilibrium initial conditions to asymptotic steady states, since researchers have been historically interested in the resilience and stability of the systems to perturbation around converged, steady (equilibrium) states and little interest has been given to the transient states which lead to the equilibrium states. Nonetheless, ecohydrological theory recognises that dryland ecosystems can often be far-from-equilibrium systems, in quasi-permanent transient condition, exhibiting non-linear responses to boundary conditions and forcings. This prompts the question of how different the behaviour of the system can be when far-from equilibrium. In this contribution we explore the role of far-from equilibrium initial hydrological conditions on both the transient and long-term asymptotically steady ecohydrological states. A simulation study was performed using the HilleRisLambers-Rietkerk ecohydrological model on a flatland varying the initial available water both near and far from equilibrium whilst also spanning the rainfall gradient (90 - 360 mm/year), performing simulations up to 200 years long. The results were assessed in terms of the evolution of total biomass yield and hydrological water balance, as well as a quantitative assessment of vegetation patterns. The results show that equilibrium conditions always yield smooth system trajectories, with little over- or undershooting, converging to the well-established patterns in the literature. However, as initial conditions move further away from equilibrium, the patterns start to differ, both in their temporal trajectory as in their long-term stable states. Conditions closer to equilibrium generate patterns with quantitative differences when compared to equilibrium conditions (e.g., larger spots). Conditions far from equilibrium can result in an entirely different hybrid patterns, consisting of a mix of spots, arcs and spirals. We evaluate these differences both qualitatively (by observing the patterns) and quantitatively, through a set of geometric indicators which describe the patterns. The results show that the patterns are history dependent and suggest that published results so far are only a subset of possible patterns. Additionally, the quantitative assessment of pattern properties in time shows that although patterns appear steady, they may indeed be slowly changing over time, while the total biomass and vegetation cover are steady early on. This has implications on the definitions of ecohydrological steady states. We also show that the effects of the idealised initial conditions on model results can be analogous to singular hydrometeorological events, as even stable patterns can be shifted into hybrid patterns by single events. Furthermore, we also explore how the new hybrid patterns compare to the well-established ones in terms of resilience to hydrological perturbations.}, language = {en} } @misc{KhoshBinGhomashCaviedesVoulliemeHinz, author = {Khosh Bin Ghomash, Shahin and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Effects of topography and infiltration heterogeneity on surface runoff and connectivity in the Huehnerwasser catchment}, series = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, journal = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, address = {Katlenburg-Lindau}, abstract = {The Huehnerwasser catchment is a monitored, early-development constructed catchment within the Lower Lausatia post-mining landscape in Germany. From the initial bare catchment state, a sequence of landscape-forming processes occurred, including erosion-based topographic change and vegetation establishment, which are at the centre of this study. Erosion-based topographic change is strongly driven by surface runoff, while in turn itself also modifying runoff in the catchment. These topographic changes can have a significant impact on the hydrological response of a catchment, as they can affect flow paths, flow speeds and rainfall-runoff-infiltration partitioning, all of which manifest in different ways in runoff hydrographs in response to rainfall events. Vegetation establishment enhances local infiltration capacity, introducing infiltration heterogeneity, thus affecting the topography-controlled flowpaths as water infiltrates at vegetation patches. Critical-zone observatories and monitored early-development systems allow to document signatures of the evolution of catchments and to correlate certain behaviours to processes. However, readily and easily achievable runoff signatures often cannot provide a clear nor full description of process interactions, as the individual roles of processes are stacked together, and strongly shaped by the temporal distribution of rainfall, making it very difficult to disentangle the effects of each process, and making modelling a necessary approach to understand these interactions and their manifestations. All such processes occur at small spatial scales, and are difficult to observe or assess when experimentally studying catchment hydrology. Moreover, given that the complexity of processes contributing to morphological changes and the corresponding alteration of runoff signatures, single catchment experiments and even comprehensive monitoring programmes of whole catchments will neither allow to decipher all processes interactions nor will it allow to apply a statistically derived experimental. In this work, we study the effects that spatial distributions of surface topography and infiltration properties have on surface runoff and surface connectivity in response to single rainfall events, in the context of the Huehnerwasser catchment. We simulate rainfall/runoff processes by means of a physically-based, spatially explicit surface flow model, and assess the results in terms of hydrological signatures (hydrograph, hydrological balance), spatial distribution of the hydrodynamics of runoff, and surface flow connectivity. To do this, we use several DEMs of the H{\"u}hnerwasser catchment recorded during the erosion-based development of the surface (2006-2010), different hypothetical infiltration properties distributions, and a set of different singular rainfall events. The study allows to observe the individual effects that topographic properties and infiltration distributions have on the hydrograph signatures and connect cause-and-effect through an intermediate, conceptual property of the system: surface runoff connectivity, arguably an indicator of hydrological organisation of the runoff response. Moreover, by systematic analysis, the interactions between topography and infiltration can also be assessed in the hydrograph and explained through connectivity. The results show a range of possible magnitudes of influence of topography and infiltration on the runoff response, while highlighting that the onset of runoff and the rising limb of the hydrograph are mostly affected by these features and their interactions, and strongly related to surface runoff connectivity.}, language = {de} } @misc{KhoshBinGhomashCaviedesVoulliemeHinz, author = {Khosh Bin Ghomash, Shahin and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Effects of erosion-induced changes to topography on runoff dynamics}, series = {Journal of Hydrology}, volume = {573}, journal = {Journal of Hydrology}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2019.04.018}, pages = {811 -- 828}, abstract = {Runoff generation from rainfall events is a complex, spatial and temporally dependent process strongly governed, among other factors, by catchment surface topography. Although it is widely known that many catchments experience morphological evolution, it is often ignored in analysis for different reasons ranging from simplification to lack of data. However, young catchments and early landscapes (such as those which are affected by natural or anthropogenic disturbances) do exhibit topography changes which in turn affect catchment hydrodynamics, hydrology and in particular runoff. In this work, we study the runoff generation and hydrodynamics of the H{\"u}hnerwasser artificial catchment (Brandenburg, Germany) during a period of erosion-based topographical changes (2006-2010). Nine Digital Elevation Models from such period were used as topography over which physically-based simulations were performed. The results suggest that topographic evolution in this catchment mostly affects the onset of runoff, whereas peak discharges and receding hydrograph limbs are less affected. These differences in hydrological signatures can be explained through the changes in the spatial distribution of runoff hydrodynamics and their impact on surface runoff connectivity. Relatively small topographical differences produce changing ponding conditions and modify flowpaths which becomes evident only through inspection of the spatial distribution of hydrodynamic variables. Moreover, the study shows that in order for simulations to be able to capture such responses, appropriate computational mesh and topographical data resolution are critical, since connectivity itself can be greatly affected by low resolution data or representation.}, language = {en} } @incollection{LacastaCaviedesVoulliemeGarciaNavarro, author = {Lacasta, Asier and Caviedes-Voulli{\`e}me, Daniel and Garc{\´i}a-Navarro, Pilar}, title = {Application of the Adjoint Method for the Reconstruction of the Boundary Condition in Unsteady Shallow Water Flow Simulation.}, series = {Advances in Evolutionary and Deterministic Methods for Design, Optimization and Control in Engineering and Sciences. Computational Methods in Applied Sciences. Part of the Computational Methods in Applied Sciences book series (COMPUTMETHODS, volume 48)}, booktitle = {Advances in Evolutionary and Deterministic Methods for Design, Optimization and Control in Engineering and Sciences. Computational Methods in Applied Sciences. Part of the Computational Methods in Applied Sciences book series (COMPUTMETHODS, volume 48)}, editor = {Minisci, Edmondo and Vasile, Massimiliano and Periaux, Jacques and Gauger, Nicolas R. and Giannakoglou, Kyriakos C. and Quagliarella, Domenico}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-319-89986-2}, doi = {10.1007/978-3-319-89988-6}, pages = {157 -- 172}, abstract = {Hydraulic phenomena in open-channel flows are usually described by means of the shallow water equations. This hyperbolic non-linear system can be used for predictive purposes provided that initial and boundary conditions are supplied and the roughness coefficient is calibrated. When calibration is required to fully pose the problem, several strategies can be adopted. In the present work, an inverse technique, useful for any of such purposes, based on the adjoint system and gradient descent is presented. It is used to find the optimal time evolution of the inlet boundary condition required to meet the 20 measured water depth data in an experimental test case of unsteady flow on a beach. The partial differential systems are solved using an upwind finite volume scheme. Several subsets of probes were selected and the quality of the reconstructed boundary tested against the experimental results. The results show that the adjoint technique is useful and robust for these problems, and exhibits some sensitivity to the choice of probes, which can be used to properly select probes in real applications.}, language = {en} } @misc{KhoshBinGhomashCaviedesVoulliemeHinz, author = {Khosh Bin Ghomash, Shahin and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Effects of topography and infiltration heterogeneity on surface runoff and connectivity in the H{\"u}hnerwasser catchment.}, series = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, journal = {European Geosciences Union, General Assembly 2019, Vienna, Austria, 7-12 April 2019}, address = {Katlenburg-Lindau}, language = {en} } @misc{OezgenXianMolinsKesserwanietal., author = {{\"O}zgen-Xian, Ilhan and Molins, Sergi and Kesserwani, Georges and Caviedes-Voullieme, Daniel and Steefel, Carl I.}, title = {Meshing workflows for multiscale hydrological simulations: Wavelet-based approach improves model accuracy.}, series = {AGU 100 : Fall Meeting 2019, San Francisco, CA, 9-13 December2019}, journal = {AGU 100 : Fall Meeting 2019, San Francisco, CA, 9-13 December2019}, address = {San Francisco, California}, pages = {1}, abstract = {The high computational cost of large-scale, process-based hydrological simulations can be approached using variable resolution meshes, where only the region around significant topographic features is refined. However, generating quality variable resolution meshes from digital elevation data is non-trivial. In literature, usually a slope or curvature-based criterion is defined to detect regions of refinement. These techniques often involve a number of free parameters that control the finest and coarsest resolutions, and the transition between fine resolution to coarse resolution. The influence of these parameters on the resulting mesh is usually not well-understood. In order to overcome the large number of free parameters involved, we propose to carry out the Mallat decomposition of the digital elevation data using the Haar wavelet. This gives a nested multilevel representation of the elevation data, split into average coefficients and detail coefficients. Applying hard-thresholding to these detail coefficients assigns a required level of refinement to each data point. This reduces the number of free parameters to exactly one: the acceptable error threshold. In this presentation, we focus on identifying which geomorphometric parameter(s) should be used to steer mesh refinement. We compare zero-inertia model simulation runs on meshes generated by decomposing elevation and slope. We hypothesize that because of the form of the Haar wavelet, the first mesh refinement essentially is using the gradient information, while the latter is using the curvature as refinement criterion. Our results suggest that in high-elevation catchments the curvature of the topography is a far better indicator for refinement than the slope. Using the Mallat decomposition on the tensor of the first derivative of the bed elevation (i.e., bed slope) for mesh refinement yields better agreement in the hydrograph compared to the decomposition of the bed elevation. We present surface runoff results for the Lower Triangle catchment, CO, USA, to illustrate the performance of the wavelet-based local mesh refinement.}, language = {en} } @misc{CaviedesVoulliemeFernandezPatoHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Fern{\´a}ndez-Pato, Javier and Hinz, Christoph}, title = {Performance assessment of 2D Zero-Inertia and Shallow Water models for simulating rainfall-runoff processes}, series = {Journal of Hydrology}, volume = {584}, journal = {Journal of Hydrology}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2020.124663}, pages = {20}, abstract = {Rainfall-runoff simulations are increasingly being performed with physically-based and spatially distributed solvers. The current computational and numerical technology enables the use of full shallow water equations solvers to be applied for these type of flow problems. Nonetheless, Zero-Inertia (diffusive wave) solvers have been historically favoured due to their conceptual and mathematical simplicity in comparison to shallow water solvers, with the working assumption that the simplifications introduced by Zero-Inertia will have some assumable impact on accuracy but will also allow for computational efficiency. Since both types of solvers have been primarily developed, benchmarked and compared to each other for fluvial and floodplain simulations, it is relevant to assess t-he relative performance for rainfall-runoff problems. In this work, both solvers are applied to a set of six well known test cases with reference solutions. The performance of the solvers is assessed in terms of global signatures such as hydrographs and flooded areas, but also in terms of spatial distributions of depth and velocity, as well as computational cost. Furthermore, the comparisons are performed across different spatial resolutions. The results show that for rainfall-runoff problems explicit, finite volumes solvers for both equations provide a similar accuracy, but the shallow water solver requires less computational time. The Zero-Inertia solver was found to be less sensitive to mesh refining than the full shallow water solver.}, language = {en} } @misc{CaviedesVoulliemeHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {From nonequilibrium initial conditions to steady dryland vegetation patterns: How trajectories matter}, series = {Ecohydrology}, volume = {13}, journal = {Ecohydrology}, number = {3}, issn = {1936-0584}, doi = {10.1002/eco.2199}, pages = {14}, abstract = {The multiscale nature of ecohydrological processes and feedbacks implies that vegetation patterns arising in water-limited systems are directly linked to water redistribution processes occurring at much shorter timescales than vegetation growth. This in turn suggests that the initially available water in the system can play a role in determining the trajectory of the system, together with the well-known role of the rainfall gradient. This work explores the role of initial hydrological conditions on vegetation dynamics and vegetation patterns. To do so, the HilleRisLambers-Rietkerk model was solved with different rainfall amounts and a large range of initial hydrological conditions spanning from near-equilibrium to far-from-equilibrium conditions. The resulting vegetation patterns and ecohydrological signatures were quantitatively studied. The results show that not only do initial hydrological conditions play a role in the ecohydrological dynamics but also they can play a dominating one even resulting in divergent vegetation patterns that exhibit convergent mean-field properties, including a new set of hybrid patterns. Our results highlight the relevance of assessing both global ecological and hydrological signatures and quantitatively assessing patterns to describe and understand system dynamics and in particular to determine if the systems are transient or steady. Furthermore, our analysis shows that the trajectories the system follows during its transient stages cannot be neglected to understand complex dependencies of the long-term steady state to environmental factors and drivers.}, language = {en} } @misc{CaviedesVoulliemeGerhardSiksteletal., author = {Caviedes-Voulli{\`e}me, Daniel and Gerhard, Nils and Sikstel, Aleksey and M{\"u}ller, Siegfried}, title = {Multiwavelet-based mesh adaptivity with Discontinuous Galerkin schemes: Exploring 2D shallow water problems}, series = {Advances in Water Resources}, volume = {138}, journal = {Advances in Water Resources}, issn = {0309-1708}, doi = {10.1016/j.advwatres.2020.103559}, pages = {29}, abstract = {In Gerhard et al. (2015a) a new class of adaptive Discontinuous Galerkin schemes has been introduced for shallow water equations, including the particular necessary properties, such as well-balancing and wetting-drying treatments. The adaptivity strategy is based on multiresolution analysis using multiwavelets in order to encode information across different mesh resolution levels. In this work, we follow-up on the previous proof-of-concept to thoroughly explore the performance, capabilities and weaknesses of the adaptive numerical scheme in the two-dimensional shallow water setting, under complex and realistic problems. To do so, we simulate three well-known and frequently used experimental benchmark tests in the context of flood modelling, ranging from laboratory to field scale. The real and complex topographies result in complex flow fields which pose a greater challenge to the adaptive numerical scheme and are computationally more ambitious, thus requiring a parallelised version of the aforementioned scheme. The benchmark tests allow to examine in depth the resulting adaptive meshes and the hydrodynamic performance of the scheme. We show that the scheme presented by Gerhard et al. (2015a) is accurate, i.e., allows to capture simultaneously large and very small flow structures, is robust, i.e., local grid refinement is controlled by just one parmeter that is auotmatically chosen and is more efficient in terms of the adaptive meshes than other shallow-water adaptive schemes achieving higher resolution with less cells.}, language = {en} } @misc{OezgenXianKesserwaniCaviedesVoulliemeetal., author = {{\"O}zgen-Xian, Ilhan and Kesserwani, Georges and Caviedes-Voulli{\`e}me, Daniel and Molins, Sergi and Xu, Zexuan and Dwivedi, Dipankar and Moulton, J. David and Steefel, Carl I.}, title = {Wavelet-based local mesh refinement for rainfall-runoff simulations}, series = {Journal of Hydroinformatics}, volume = {22}, journal = {Journal of Hydroinformatics}, number = {5}, issn = {1464-7141}, doi = {10.2166/hydro.2020.198}, pages = {1059 -- 1077}, abstract = {A wavelet-based local mesh refinement (wLMR) strategy is designed to generate multiresolution and unstructured triangular meshes from real digital elevation model (DEM) data for efficient hydrological simulations at the catchment scale. The wLMR strategy is studied considering slope- and curvature-based refinement criteria to analyze DEM inputs: the slope-based criterion uses bed elevation data as input to the wLMR strategy, whereas the curvature-based criterion feeds the bed slope data into it. The performance of the wLMR meshes generated by these two criteria is compared for hydrological simulations; first, using three analytical tests with the systematic variation in topography types and then by reproducing laboratory- and real-scale case studies. The bed elevation on the wLMR meshes and their simulation results are compared relative to those achieved on the finest uniform mesh. Analytical tests show that the slope- and curvature-based criteria are equally effective with the wLMR strategy, and that it is easier to decide which criterion to take in relation to the (regular) shape of the topography. For the realistic case studies: (i) slope analysis provides a better metric to assess the correlation of a wLMR mesh to the fine uniform mesh and (ii) both criteria predict outlet hydrographs with a close predictive accuracy to that on the uniform mesh, but the curvature-based criterion is found to slightly better capture the channeling patterns of real DEM data.}, language = {en} } @misc{SchuettCaviedesVoulliemeHinz, author = {Sch{\"u}tt, Claudia and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Exploring the effects of rainfall variability on banded vegetation}, series = {EGU General Assembly 2020, Online, 4-8 May 2020}, journal = {EGU General Assembly 2020, Online, 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-13238}, language = {en} } @misc{CaviedesVoulliemeGerhardSiksteletal., author = {Caviedes-Voulli{\`e}me, Daniel and Gerhard, Nils and Sikstel, Aleksey and M{\"u}ller, Siegfried}, title = {Adaptive 2D shallow water simulation based on a MultiWavelet Discontinous Galerkin approach}, series = {EGU General Assembly 2020, Online, 4-8 May 2020}, journal = {EGU General Assembly 2020, Online, 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-14464}, language = {en} } @misc{NonesCaviedesVoullieme, author = {Nones, Michael and Caviedes-Voulli{\`e}me, Daniel}, title = {Computational advances and innovations in flood risk mapping}, series = {Journal of Flood Risk Management}, volume = {13}, journal = {Journal of Flood Risk Management}, number = {4}, issn = {1753-318X}, doi = {10.1111/jfr3.12666}, pages = {3}, language = {en} } @misc{MoralesHernandezOezgenXianCaviedesVoullieme, author = {Morales-Hernandez, Mario and {\"O}zgen-Xian, Ilhan and Caviedes-Voulli{\`e}me, Daniel}, title = {Effects of microtopography across spatial scales: studying hydrological response through high-resolution shallow-water modelling}, series = {EGU General Assembly 2020, Online, 4-8 May 2020}, journal = {EGU General Assembly 2020, Online, 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-10655}, language = {en} } @misc{RojasCaviedesVoulliemeHinz, author = {Rojas, Pedro and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Semi-automatic image analysis of spatiotemporal vegetation evolution in the H{\"u}hnerwasser catchment}, series = {EGU General Assembly 2020, Online, 4-8 May 2020}, journal = {EGU General Assembly 2020, Online, 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-13522}, language = {en} } @misc{AhmadiniaCaviedesVoulliemeHinz, author = {Ahmadinia, Ebrahim and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Coupled effects of microtopography and time-dependant infiltration capacity on rainfall-runoff-infiltration partitioning on a hillslope}, series = {EGU General Assembly 2020, Online, 4-8 May 2020}, journal = {EGU General Assembly 2020, Online, 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-18200}, language = {en} } @misc{HinzMengsuwanCaviedesVoullieme, author = {Hinz, Christoph and Mengsuwan, Konlavach and Caviedes-Voullieme, Daniel}, title = {Spatial analytics of self-organized vegetation pattern in semi-arid regions: an example on tiger-bush patterns in Sudan}, series = {EGU General Assembly 2021}, journal = {EGU General Assembly 2021}, doi = {10.5194/egusphere-egu21-10102}, language = {en} } @misc{CaviedesVoulliemeOezgenXianHinz, author = {Caviedes-Voulli{\`e}me, Daniel and {\"O}zgen-Xian, Ilhan and Hinz, Christoph}, title = {Surface runoff connectivity across scales: revisiting three simulation studies}, series = {EGU General Assembly 2021}, journal = {EGU General Assembly 2021}, doi = {10.5194/egusphere-egu21-5004}, language = {en} } @misc{CaviedesVoulliemeAhmadiniaHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Ahmadinia, Ebrahim and Hinz, Christoph}, title = {Interactions of Microtopography, Slope and Infiltration Cause Complex Rainfall-Runoff Behavior at the Hillslope Scale for Single Rainfall Events}, series = {Water Resources Research}, volume = {57}, journal = {Water Resources Research}, number = {7}, issn = {1944-7973}, doi = {10.1029/2020WR028127}, pages = {20}, 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.}, language = {en} } @misc{KaestnerCaviedesVoulliemeFrechenetal., author = {K{\"a}stner, Karl and Caviedes-Voullieme, Daniel and Frechen, Tobias Nanu and Hinz, Christoph}, title = {Theory and empirical evidence for the irregularity of self-organized vegetation patterns}, series = {EGU General Assembly 2022, Vienna, Austria, 23-27 May 2022}, journal = {EGU General Assembly 2022, Vienna, Austria, 23-27 May 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.}, language = {en} } @misc{KaestnerHinzCaviedesVoulliemeetal., author = {K{\"a}stner, Karl and Hinz, Christoph and Caviedes-Voulli{\`e}me, Daniel and Frechen, Tobias Nanu and Vijsel, Roeland C. van de}, title = {A metaanalysis of the regularity of environmental spatialpatterns and a theory relating them to stochastic processes}, series = {EGU General Assembly 2023, Vienna, Austria, 24-28 Apr 2023}, journal = {EGU General Assembly 2023, Vienna, Austria, 24-28 Apr 2023}, doi = {10.5194/egusphere-egu23-5817}, language = {en} } @misc{ShlewetCaviedesVoulliemeKaestneretal., author = {Shlewet, Marlin and Caviedes-Voulli{\`e}me, Daniel and K{\"a}stner, Karl and Hinz, Christoph}, title = {Effects of urban structures on spatial and temporal flood distribution}, series = {EGU General Assembly 2023, Vienna, Austria, 24-28 Apr 2023}, journal = {EGU General Assembly 2023, Vienna, Austria, 24-28 Apr 2023}, doi = {10.5194/egusphere-egu23-9498}, language = {en} }