@misc{CaviedesVoulliemeMoralesHernandezJuezetal., author = {Caviedes-Voulli{\`e}me, Daniel and Morales-Hern{\´a}ndez, Mario and Juez, Carmelo and Lacasta, Asier and Garc{\´i}a-Navarro, Pilar}, title = {Two-Dimensional Numerical Simulation of Bed-Load Transport of a Finite-Depth Sediment Layer: Applications to Channel Flushing}, series = {Journal of Hydraulic Engineering}, volume = {143}, journal = {Journal of Hydraulic Engineering}, number = {9}, issn = {0733-9429}, doi = {10.1061/(ASCE)HY.1943-7900.0001337}, pages = {04017034}, abstract = {Numerical modeling of bed-load transport in shallow flows, particularly oriented toward environmental flows, is an active field of research. Nevertheless, other possible applications exist. In particular, bed-load transport phenomena are relevant in urban drainage systems, including sewers. However, few applications of coupled two-dimensional (2D) shallow-water and bed-load transport models can be found, and their transfer from environmental applications — usually river and floodplain — into sewer applications requires some adaptation. Unlike to river systems, where there is a thick layer of sediment that constitutes a movable riverbed, sewer systems have thin layers of sediment that need to be removed, thus exposing a rigid, nonerodible surface. This problem requires careful numerical treatment to avoid generating errors and instability in the simulation. This paper deals with a numerical approach to tackle this issue in an efficient way that allows large-scale studies to be performed and provides empirical evidence that the proposed approach is accurate and applicable for sewage and channel-flushing problems.}, language = {en} } @inproceedings{CaviedesVoulliemeAndezhathMohananBruecketal., author = {Caviedes-Voullieme, Daniel and Andezhath Mohanan, Anju and Br{\"u}ck, Yasemine and Zaplata, Markus K. and Hinz, Christoph}, title = {Effect of surface water redistribution on vegetation encroachment in the constructed H{\"u}hnerwasser catchment}, series = {M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beitr{\"a}ge zum Tag der Hydrologie am 22./23. M{\"a}rz 2018 an der Technischen Universit{\"a}t Dresden}, booktitle = {M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beitr{\"a}ge zum Tag der Hydrologie am 22./23. M{\"a}rz 2018 an der Technischen Universit{\"a}t Dresden}, editor = {Sch{\"u}tze, Niels and M{\"u}ller, Uwe and Schwarze, Robert and W{\"o}hling, Thomas and Grundmann, Jens}, publisher = {Technische Universit{\"a}t}, address = {Dresden}, pages = {S. 91}, abstract = {The artificial H{\"u}hnerwasser catchment has experienced a significant and monitored evolution since 2005, changing from a post-mining landscape to an almost fully vegetated ecosystem. The early stages showed a fast rate of ecohydrological evolution with changing dominating processes and feedbacks. The evolution of rill vegetation encroachment is one of such complex co-evolving processes. We hypothesise that rill vegetation encroachment is driven by the evolution of the hydrologic/hydraulic regime of the rill network, which in turn affects the regime, potentially creating a stabilising positive feedback. We further hypothesise that rill vegetation occurs later than hillslope vegetation, and follows a particular establishment and encroachment timeline in response to the changing hydrological/hydraulic regimes. That is, the early runoff-dominated regime results in higher flows, velocities, transport and erosion capacity, thus favouring seed flushing and seedling uprooting. On the other hand, as the system transitions from a runoffdominated into an infiltration- and ET-dominated system, flow, velocity, transport and erosion capacity in the rill network are reduced, making seed establishment in the rills more likely. We explore these hypothesis with two complementary approaches: an analysis of the spatiotemporal distribution of vegetation and a process-based numerical modelling study. Firstly, we assess aerial photography of rill vegetation encroachment between 2007 and 2012 in terms of several vegetation types to derive temporal indicators of encroachment. The analysis reveals that in the initial stages, a rill network developed in the hillslope. Shortly after vegetation first established on hillslopes, the rill network became progressively vegetated. Different pioneering species established heterogeneously, at different times and encroached into the rills at different rates. However, despite the volume of data, it is difficult to assess which are the governing and limiting processes which respectively drive and constrain how and at which rate vegetation encroaches into the rills. In consequence, a pilot modelling study to identify the relative relevance of rill network geometry, bare soil infiltration, hillslope vegetation heterogeneity and intra-storm variability on the hydraulic response of the rill network and its possible impact on encroachment. The overall results suggest that vegetation encroachment may be controlled by the rill network hydraulic regime, but such regime is the result of a complex superposition of responses of all the aforementioned factors, of which rill geometry appears to be a dominant one. Furthermore, the simulations showed that vegetation spatial heterogeneity has an impact on the hydraulic regime coupled to the presence of temporal rainfall variability. Altogether, these results show that the governing coevolving ecohydrological processes are interacting and are strongly affected by spatial and temporal heterogeneities.}, language = {en} } @inproceedings{CaviedesVoulliemeMartı́nezArandaFernandezPatoetal., author = {Caviedes-Voullieme, Daniel and Mart{\i}́nez-Aranda, Sergio and Fern{\´a}ndez-Pato, Javier and Garc{\´i}a-Palac{\´i}n, Ignacio and Garc{\´i}a-Navarro, Pilar}, title = {Measuring 2D transient shallow water surfaces: raising the benchmark challenges for 2D shallow water solvers}, series = {M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beitr{\"a}ge zum Tag der Hydrologie am 22./23. M{\"a}rz 2018 an der Technischen Universit{\"a}t Dresden}, booktitle = {M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beitr{\"a}ge zum Tag der Hydrologie am 22./23. M{\"a}rz 2018 an der Technischen Universit{\"a}t Dresden}, editor = {Sch{\"u}tze, Niels and M{\"u}ller, Uwe and Schwarze, Robert and W{\"o}hling, Thomas and Grundmann, Jens}, publisher = {Technische Universit{\"a}t}, address = {Dresden}, pages = {S. 23}, abstract = {In the past decade, shallow water (SW) solvers have been dramatically improved both in terms of accuracy and computational power. The mathematical, numerical and computational improvements available in state-of-the-art solvers now allow for large scale, long term, high resolution simulations of river flooding, flash floods, dam-break phenomena, rainfall-runoff simulation and extensions into pollutants, substance and sediment transport, etc. SW solvers have been benchmarked against a set of test cases, ubiquitious in the literature. The solvers have been systematically verified against 1D and some 2D analytical solutions and validated further against 1D and 2D laboratory experiments, as well as some well-documented real-scale field cases. However, despite the 2D nature of many of these benchmark tests, none of them report 2D water surface elevation. Typically a few profiles are measured and reported, and more often, only a few points are available. Moreover, in field cases, often not even fully transient data is available. The reason for the inavailability of 2D transient water surface data is due to the technical difficulty of measuring a (fast) moving water surface. In most of the reported experiments, pressure gauges are often used to register water depth evolution, and sometimes PIV techniques have been used to obtain velocity fields. In experimental fluid mechanics, measuring the evolution of a free surface has received little attention, as it has been mainly understood as a problem for SW flows, and more recently for free surface granular flows. In consequence, this work aims to generate a new benchmarking dataset in which 2D transient water surfaces are available for SW model developers and users to further test and challenge these models. We argue that the availability of this new data can help identify limitations in the current generation of solvers, thus laying the ground for improvements in the near future. We present laboratory-scale experimental results on steady and unsteady 2D water surfaces performed in a laboratory flume, ranging from steady transcritical flow to dam-break flows around obstacles. The transient water surface was captured using a commercial-grade RGBD sensing device which allows to capture a high-frequency succession of 3D color-coded point clouds. The channel bed can also be registered in the same manner, thus also allowing to compute the 2D transient water-depth field. Color coding also allows to easily differentiate the channel bed, sidewalls and obstacles. The result of the experimental study is a novel collection of 2D benchmark SW cases, with transient water depth and water elevation data for the entire visible flow field. Furthermore, we compare the experimental measurements to 2D shallow water simulations performed with an extensively tested state-of-the-art solver to assess the suitability of this dataset to perform as benchmark test cases and identify some potential limitations of current models.}, language = {en} } @inproceedings{CaviedesVoulliemeHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {The role of topography and intra-annual rainfall variability in semi-arid vegetation self-organisation: a multi-scale modelling study}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {Coevolution of hydrological and vegetation dynamics in semi-arid regions has been widely observed to result in vegetation self-organisation (VSO). Many hypothesis of VSO's underlying ecohydrological processes and feedbacks have been studied relying on mathematical models, which have been key to evaluate the sensitivity of ecohydrological systems to environmental factors and drivers. Although this ecohydrological coevolution is essentially multiscale, researchers have continued to be constrained by the simplicity of the models which are unable to cope with the multiscale, process-based complexity of fast-moving surface water over complex topographies driven by varying rainfall, during decade-to-century long VSO processes. This limitation has not allowed deep exploration of the role and sensitivity of key environmental factors such as topography and rainfall variability, and the lack of proper hydrodynamics still constrains adequate sediment transport modelling and its feedback effects on VSO. We hypothesize that the intra-storm water redistribution by surface runoff at the hillslope scale is strongly controlled by both topography and storm intensity and may control VSO. This requires for these environmental factors to be accurately represented in models and their their hydraulic and hydrological effects properly reflected. This work provides the first systematic study of the effects of topography and intra-annual rainfall distributions on vegetation band formation at the hillslope scale. Simulations were performed with a physically-based numerical model solving the Zero-Inertia approximation to the shallow water equations for surface flow coupled to the HilleRisLambers-Rietkerk vegetation model, allowing to explicitly represent arbitrary topography. An idealized study of ecohydrological evolution over 30 years was performed, solving with a temporal resolution in the seconds scale. Plane, convex and convex hillslope topologies with different slopes were used, while forcing the model with different annual rainfalls along a semi-arid rainfall gradient, with discrete events of different frequencies. We describe results in terms of evolution of total biomass, hydrological water balance, and of the spatial properties of banded vegetation. Results show that both topography and intra-annual rainfall distribution can play a shaping and governing role in VSO by controlling surface water redistribution and the hydrologic water balance. Increasing slopes favours runoff over infiltration, reducing the available water for vegetation and resulting in different evolutions of vegetation band geometry and band migration. Hillslope topology plays a strong role in the internal water redistribution of the system. Plane and convex surfaces behave similarly, but concave surfaces exhibit a different ecohydrological behaviour, despite the very small topological differences. Different intra-annual rainfall distributions result in different rainfall intensities for the same total annual rainfall which strongly affect the band formation and evolution process: higher intensities lead to less available water, to which vegetation adapts by spatially clustering in bands with different geometrical properties. The study also shows that it is computationally feasible (a few hours runtime) to perform decade-to-century long simulations of these systems with physically-based numerical models paving the way to simulate natural systems with arbitrary topography and high-resolution rainfall data, and is a first step in introducing physically-based sediment transport processes and feedbacks in these studies.}, language = {en} } @inproceedings{BrueckAndezhathMohananCaviedesVoulliemeetal., author = {Br{\"u}ck, Yasemine and Andezhath Mohanan, Anju and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph and Zaplata, Markus K.}, title = {Spatio-temporal development of rill vegetation in the H{\"u}hnerwasser Catchment}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, 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 hillslope scale. Early on, rain-induced rill and channels formation was observed, followed by vegetation growth in between rills, and later on inside the rills. In this work, we aim to describe the temporal evolution of the spatial distribution of rill vegetation. In general terms, we hypothesize four different encroachment patterns might occur: (1) The vegetation spreads from the top of the rills downstream. The underlying hypothesis would be a higher establishment probability due to a lower velocity of surface runoff and therefore less transport probability compared to downstream rill segments. (2) The vegetation starts growing downstream and moves upwards. In this case we can hypothesize that the spatial distribution of the vegetation is dominated by water availability, which is higher or more stable downstream. (3) The vegetation encroaches from the sides into the rills, meaning that inter-rill vegetation governs vegetation encroachment inside the rills. (4) If no patterns are detected it might mean that the encroachment process depends strongly on very local conditions, or perhaps that the underlying assumption of an initially homogeneous seed distribution is false. To investigate the rills formation and rill vegetation encroachment processes, rills and vegetation patches inside these rills were identified and digitized from aerial photographs of the catchment from 2007 to 2012. Different vegetation types were identified based on the colour and texture of the patches. The geometrical properties of the rill segments and vegetation patches were used to define how the different vegetation types have distributed in space and how this distribution has changed over time. Rill mapping reveals a large increase of rill area from 2007 to 2008 and only a small rise from 2008 to 2009. Starting in 2010 dense vegetation prevents a precise mapping of the rills in the aerial photographs, so we assume that there is no change in rill area from 2009 to 2012. In 2007 vegetation covered only 1.4\% of the rill area. There is only a small increase of this area in 2008 compared to the later years. In 2012 more than 50\% of the rill area is covered by plants. Ten different vegetation types have been identified in the aerial photographs, starting with two types in 2007. By 2012 nine types are spotted in the rills of the catchment. Some of these vegetation types show an encroachment from up- to downstream (e.g. Tussilago farfara), some from down- to upstream like Phragmites australis, whose creeping rhizomes can also promote such spreading. Others reveal no patterns. To better assess and identify the underlying processes leading to these encroachment processes shown by the different vegetation types further data analysis -e.g. comparison with ground based vegetation mapping- and process-based hydrological modelling is necessary to fully explain these observations and assessing additional competition effects, which may be at play.}, language = {en} } @inproceedings{CaviedesVoulliemeAndezhathMohananBruecketal., author = {Caviedes-Voulli{\`e}me, Daniel and Andezhath Mohanan, Anju and Br{\"u}ck, Yasemine and Hinz, Christoph}, title = {Rill hydrodynamics and its impact on rill vegetation encroachment: a modelling study of the constructed H{\"u}hnerwasser catchment}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {The H{\"u}hnerwasser catchment is a monitored, early-development constructed catchment within the Lower Lausatia post-mining landscape in Germany. Observations have shown that a sequence of landscape-forming processes occurred, including the initial vegetation establishment stages, which are the main interest of this study. In the initial stages of geomorphic development a surface drainage network of rills was formed as vegetation started to appear on the hillslopes and subsequently inside the rill network. Observations and analysis of the rill vegetation establishment suggest that different vegetation types encroach into the rill network at different times, rates and form different directions. We hypothesize that these encroachment processes may respond to the runoff properties of the catchment at such time: velocity distribution in the rills might play a significant role in flushing seeds in high-velocity reaches of the rill network, thus favouring the appearance of vegetation in low-velocity regions. Consequently, the goal of this study is to assess the magnitudes and spatiotemporal behaviour of velocity in the rill network, to assess its possible impact on seed flushing and rill vegetation encroachment. One rill subcatchment of H{\"u}hnerwasser was selected to perform an explorative study of rill hydrodynamics and their impact on vegetation establishment. Two vegetation states were simulated: bare hillslopes and vegetated hillslopes. The vegetated cover polygons were obtained from digitized aerial photography, and stochastically dissagregated 10-minute resolution precipitation data were used, selecting events with early, middle and late peak storm intensities. A 2D explicit finite volume scheme solving the Zero-Inertia approximation to the shallow water equations was used to simulate surface flow in the subcatchment. The preliminary modelling results suggest that that there is no clear overall velocity gradient in the downstream direction along the rills. In fact, velocity in the rills may increase or decrease along the rill following local topography and rill geometry. Consequently, no global trend for the probability of seeds being transported can be established. The results also shows that varying rainfall intensity and rainfall intrastorm distribution -in the absence of hillslope vegetation- does not affect the rill locations of maximum velocities, but mostly affect the magnitude of velocity. In the presence of hillslope vegetation -and thus heterogeneous infiltration conditions in the hillslopes- the spatial distribution of velocity is strongly affected, and can be in fact governed not by topography or rill geometry, but by the spatial heterogeneity of infiltration capacity. Furthermore, the time at which maximum discharge and velocities occur may not match that of maximum intensity. That is, emerging temporal dynamics arise due to the introduction of spatial heterogeneity, which also manifests in the fact that outflow from the subcatchment exhibits a intensity-thresholded behaviour.}, language = {en} } @inproceedings{CaviedesVoulliemeHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Convergent biomass, divergent patterns: Can initial conditions govern vegetation self-organisation?}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, 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 states on domains with periodic boundaries and forced by steady rainfall, whilst little interest has been given to the transient states which lead to them as well as the spatiotemporal multiscale nature of the feedback processes. It is generally accepted that alternative random initial biomass distributions do not significantly affect the resulting steady state vegetation patterns. However, the role of the initial hydrological conditions -initial surface and subsurface water- has not been explored, mainly due to the interest in the long-term steady state. Nonetheless, vegetation patterns are directly linked to the water distribution occurring at much shorter time scales than vegetation growth, and because they have been shown to be sensitive to annual rainfall, it is reasonable that the initially available water will also play a role. We therefore hypothesize that the initially available water will play a role in the transient process leading to a steady ecohydrological state, and that the steady vegetation patterns will differ in response to the water availability in time during the entire process. In this contribution we explore the role of initial hydrological conditions on both the transient and longterm steady ecohydrological state. A simulation study was performed using the HilleRisLambers-Rietkerk ecohydrological model on a flatland varying the initial available water whilst also spanning the rainfall gradient (90 - 360 mm/year) . The results were assessed in terms of the evolution and steady state of total biomass yield and hydrological water balance, as well as a quantitative assessment of both transient and steady vegetation patterns. The results show that the initially available water does play a role, not only in the early transient state, but in the long-term steady state, and indeed in the geometry of the converged vegetation pattern. Furthermore, although the steady state biomass yield may be the same for varying initial conditions, the final patterns still differ, e.g., a reduction to one-fourth initial water availability results in more but smaller vegetation patches, while a reduction to one-eigth initial water results in less, but larger patches, and a reduction to one-sixteenth results in a completely new pattern, although total biomass is the same for all. This suggests that long-term average rainfall may govern the total biomass but the initial conditions may play a relevant shaping role in the long term spatial distributions of steady ecohydrological states of water-limited ecohydrosystems. This is relevant, among other reasons, because the resilience of the system is associated to the vegetation patterns. It also suggests that neither the temporal distribution of rainfall nor the system's evolution cannot be neglected to understand the environmental factors which lead to a steady ecohydrological state, since multiple paths may be possible. This warrants further developments from the ecohydrological modelling community and further study of transient states through process-based models.}, language = {en} } @misc{CaviedesVoulliemeFernandezPatoHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Fern{\´a}ndez-Pato, Javier and Hinz, Christoph}, title = {Cellular Automata and Finite Volume solvers converge for 2D shallow flow modelling for hydrological modelling}, series = {Journal of Hydrology}, volume = {563}, journal = {Journal of Hydrology}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2018.06.021}, pages = {411 -- 417}, abstract = {Surface flows of hydrological interest, including overland flow, runoff, river and channel flow and flooding have received significant attention from modellers in the past 30 years. A growing effort to address these complex environmental problems is in place in the scientific community. Researchers have stud-ied and favoured a plethora of techniques to approach this issue, ranging from very simple empirically-based mathematical models, to physically-based, deductive and very formal numerical integration of systems of partial-differential equations. In this work, we review two families of methods: cell-based simulators - later called Cellular Automata - and Finite Volume solvers for the Zero-Inertia equation, which we show to converge into a single methodology given appropriate choices. Furthermore, this convergence, mathematically shown in this work, can also be identified by critically reviewing the exist-ing literature, which leads to the conclusion that two methods originating from different reasoning and fundamental philosophy, fundamentally converge into the same method. Moreover, acknowledging such convergence allows for some generalisation of properties of numerical schemes such as error behaviour and stability, which, importantly, is the same for the converging methodology, a fact with practical implications. Both the review of existing literature and reasoning in this work attempts to aid in the effort of synchronising and cross-fertilizing efforts to improve the understanding and the outlook of Zero-Inertia solvers for surface flows, as well as to help in clarifying the possible confusion and parallel develop-ments that may arise from the use of different terminology originating from historical reasons. Moreover, synchronising and unifying this knowledge-base can help clarify model capabilities, applicability and modelling issues for hydrological modellers, specially for those not deeply familiar with the mathematical and numerical details.}, language = {en} } @inproceedings{CaviedesVoulliemeFernandezPatoHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Fern{\´a}ndez-Pato, Javier and Hinz, Christoph}, title = {Zero-Inertia vs full shallow water equations: a comparison for rainfall-runoff modelling}, series = {Computational Methods in Water Resources XXII (CMWR 2018), Bridging gaps between data, models, and predictions}, booktitle = {Computational Methods in Water Resources XXII (CMWR 2018), Bridging gaps between data, models, and predictions}, pages = {2}, language = {en} } @inproceedings{CaviedesVoulliemeHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {An ecohydrological model to explore topographic and rainfall variability effects on vegetation self-organisation}, series = {Computational Methods in Water Resources XXII (CMWR 2018), Bridging gaps between data, models, and predictions}, booktitle = {Computational Methods in Water Resources XXII (CMWR 2018), Bridging gaps between data, models, and predictions}, pages = {2}, language = {en} } @inproceedings{VarraniCaviedesVoulliemeHinz, author = {Varrani, Arianna and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Dynamic mapping of surface topografy at rainfall events}, series = {Proceedings of the 5th IAHR Europe Congress — New Challenges in Hydraulic Research and Engineering}, booktitle = {Proceedings of the 5th IAHR Europe Congress — New Challenges in Hydraulic Research and Engineering}, editor = {Armanini, Aronne and Nucci, Elena}, publisher = {IAHR Secretariat, Department of Civil, Environmental and Mechanical Engineering}, address = {Madrid, Spain}, isbn = {978-981-11-2731-1}, pages = {139 -- 140}, abstract = {Landscape evolution forced by rainfall is simulated at the laboratory scale and dynamically tracked using six virtual sensors Kinect™ to ensure detailed meas-urements with relatively low-cost devices.}, language = {en} } @misc{Martı́nezArandaFernandezPatoCaviedesVoulliemeetal., author = {Mart{\i}́nez-Aranda, Sergio and Fern{\´a}ndez-Pato, Javier and Caviedes-Voulli{\`e}me, Daniel and Garc{\´i}a-Palac{\´i}n, Ignacio and Garc{\´i}a-Navarro, Pilar}, title = {Towards transient experimental water surfaces: A new benchmark dataset for 2D shallow water solver}, series = {Advances in Water Resources}, volume = {121}, journal = {Advances in Water Resources}, issn = {0309-1708}, doi = {10.1016/j.advwatres.2018.08.013}, pages = {130 -- 149}, abstract = {In the past decade, shallow water solvers have dramatically improved both in terms of accuracy and computational power. New mathematical models and numerical schemes have been systematically verified against 1D exact solutions and laboratory experiments. Despite the two-dimensional nature of some of these benchmark tests, none of them reports complete 2D water depth fields, but only a few profiles are measured and reported in the best case. This work reports a new benchmarking dataset for validation of shallow water solvers, in which two-dimensional transient water depth measurements are available for complex steady and transient laboratory flume experiments, ranging from transcritical steady flow to dam-break flows around obstacles and complex beds. The transient water surface was measured using a commercial-grade RGB-D sensing device which allows to capture a succession of color-coded point clouds at a high frequency. These experimental measurements are compared with 2D shallow water simulations carried out with an extensively tested finite volume solver. Results asses the suitability of this dataset to perform as benchmark tests, identifying potential limitations of current and future models.}, language = {en} } @inproceedings{Martı́nezArandaFernandezPatoCaviedesVoulliemeetal., author = {Mart{\i}́nez-Aranda, Sergio and Fern{\´a}ndez-Pato, Javier and Caviedes-Voulli{\`e}me, Daniel and Garc{\´i}a-Palac{\´i}n, Ignacio and Garc{\´i}a-Navarro, Pilar}, title = {Towards transient 2D experimental water surfaces: strengthening SW model validation}, series = {HIC 2018, 13th International Conference on Hydroinformatics}, booktitle = {HIC 2018, 13th International Conference on Hydroinformatics}, editor = {La Loggia, Goffredo and Freni, Gabriele and Puleo, Valeria and De Marchis, Mauro}, doi = {10.29007/qpmx}, pages = {1324 -- 1331}, abstract = {The measurement and simulation of 2D free-surface shallow flows is carried out in this work. For the experimental study a 3D-sensing device (Microsoft Kinect) is used to measure both steady and transient water surface elevation fields with different flow characteristics. This procedure provides 640x480 px resolution water surface level point clouds with a frequency ranging from 8 Hz to 30 Hz. The experimental measurements are compared with 2D finite volume simulations carried out by means of a robust and well-balanced numerical scheme able to deal with flow regime transitions and wet/dry fronts. A good agreement is found between experimental and numerical results for all the cases studied, demonstrating the capability of the RGB-D sensor to capture the water free-surface position accurately. This new experimental technique, which allows us to obtain 2D water depth fields in open- channel flows, leads to a wide range of promising capabilities in order to validate new shallow water models and to improve their accuracy and performance.}, language = {en} } @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} } @misc{ShlewetKaestnerCaviedesVoulliemeetal., author = {Shlewet, Marlin and K{\"a}stner, Karl and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Einfluss urbaner Strukturen auf die r{\"a}umliche und zeitliche Dynamik pluvialer Fluten}, series = {Abstract-Band, Tag der Hydrologie 2023, Nachhaltiges Wassermanagement - Regionale und Globale Strategien, 22. \& 23.03.2023, Ruhr-Universit{\"a}t Bochum \& Hochschule Bochum}, journal = {Abstract-Band, Tag der Hydrologie 2023, Nachhaltiges Wassermanagement - Regionale und Globale Strategien, 22. \& 23.03.2023, Ruhr-Universit{\"a}t Bochum \& Hochschule Bochum}, language = {de} } @misc{KaestnerVijselCaviedesVoulliemeetal., author = {K{\"a}stner, Karl and Vijsel, Roeland C. van de and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Unravelling the spatial structure of regular environmental spatial patterns}, series = {EGU General Assembly 2024, Vienna, Austria \& Online, 14-19 April 2024}, journal = {EGU General Assembly 2024, Vienna, Austria \& Online, 14-19 April 2024}, publisher = {Copernicus GmbH}, doi = {10.5194/egusphere-egu24-3412}, abstract = {Spatial patterns where patches of high biomass alternate with bare ground occur in many resource-limited ecosystems. Especially fascinating are regular patterns, which are self-similar at a lag distance corresponding to the typical distance between patches. Regular patterns are understood to form autogenously through self-organization, which can be generated with deterministic reaction-diffusion models. Such models generate highly regular patterns, which repeat at the characteristic wavelength and are therefore periodic. Natural patterns do not repeat, as they are noisy and as the patch size and spacing vary. Natural patterns are therefore usually perceived as perturbed periodic patterns. However, the self-similarity of natural patterns decreases at longer lag distances, which indicates that their spatial structure is not a perturbed periodic structure originating through deterministic processes. Here, we provide an overview of our recent work on the spatial structure and formation of natural environmental spatial patterns as a basis for discussion: First, we develop a statistical periodicity test and compile a large dataset of more than 10,000 regular environmental spatial patterns. We find that neither isotropic (spotted) nor anisotropic (banded) patterns are periodic. Instead, we find that their spatial structure can be well described as random fields originating through stochastic processes. Second, we recognize the regularity as a gradually varying property, rather than a dichotomous property of being periodic or not. We develop a method for quantifying the regularity and apply it in a metastudy to a set of natural and model-generated patterns found in the literature. We find that patterns generated with deterministic reaction-diffusion models do not well reproduce the spatial structure of environmental spatial structure, as they are too regular. Third, we develop an understanding of pattern formation through stochastic reaction-diffusion processes, which incorporate random environmental heterogeneities. We find that regular patterns form through filtering of the environmental heterogeneities and identify stochastic processes which reproduce both isotropic and anisotropic patterns.}, language = {en} } @misc{KaestnerVijselCaviedesVoulliemeetal., author = {K{\"a}stner, Karl and Vijsel, Roeland C. van de and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {A scale-invariant method for quantifying the regularity of environmental spatial patterns}, series = {Ecological Complexity}, volume = {60}, journal = {Ecological Complexity}, publisher = {Elsevier BV}, issn = {1476-945X}, doi = {10.1016/j.ecocom.2024.101104}, pages = {13}, abstract = {Spatial patterns of alternating high and low biomass occur in a wide range of ecosystems. Patterns can improve ecosystem productivity and resilience, but the particular effects of patterning depend on their spatial structure. The spatial structure is conventionally classified as either regular, when the patches of biomass are of similar size and are spaced in similar intervals, or irregular. The formation of regular patterns is driven by scale-dependent feedbacks. Models incorporating those feedbacks generate highly regular patterns, while natural patterns appear less regular. This calls for a more nuanced quantification beyond a binary classification. Here, we propose measuring the degree of regularity by the maximum of a pattern's spectral density, based on the observation that the density of highly regular patterns consists of a narrow and high peak, while the density of highly irregular patterns consists of a low and wide lobe. We rescale the density to make the measure invariant with respect to the characteristic length-scale of a pattern, facilitating the comparison of patterns observed or modelled under different conditions. We demonstrate our method in a metastudy determining the regularity of natural and model-generated patterns depicted in previous studies. We find that natural patterns have an intermediate degree of regularity, resembling random surfaces generated by stochastic processes. We find that conventional deterministic models do not reproduce the intermediate regularity of natural patterns, as they generate patterns which are much more regular and similar to periodic surfaces. We call for appreciating the stochasticity of natural patterns in systems with scale-dependent feedbacks.}, language = {en} } @misc{KaestnerVijselCaviedesVoulliemeetal., author = {K{\"a}stner, Karl and Vijsel, Roeland C. van de and Caviedes-Voulli{\`e}me, Daniel and Frechen, Nanu T. and Hinz, Christoph}, title = {Unravelling the spatial structure of regular dryland vegetation patterns}, series = {CATENA}, volume = {247}, journal = {CATENA}, publisher = {Elsevier BV}, issn = {0341-8162}, doi = {10.1016/j.catena.2024.108442}, pages = {13}, abstract = {Many resource-limited ecosystems exhibit spatial patterns where patches of biomass alternate with bare ground. Patterns can enhance ecosystem functioning and resilience, depending on their spatial structure. Particularly conspicuous are regular patterns, where patches are of similar size and spaced in similar intervals. The spatial structure of regular patterns is often described to be periodic. This has been corroborated by statistical testing of natural patterns and generation of periodic patterns with deterministic reaction-diffusion models. Yet, natural regular patterns appear conspicuously erratic compared to periodic patterns. So far, this has been attributed to perturbations by noise, varying patch size and spacing. First, we illustrate by means of an example that the spatial structure of regular vegetation patterns cannot be reproduced by perturbing periodic patterns. We then compile a large dataset of regular dryland patterns and find that their spatial structure systematically differs from periodic patterns. We further reveal that previous studies testing for periodicity overlook two aspects which dramatically inflate the number of false positives and result in the misclassification of patterns as periodic. We amend the test procedure by accounting for both aspects, finding that regular natural patterns have no significant periodic components. Lastly, we demonstrate that stochastic processes can generate regular patterns with similar visual appearance, spatial structure and frequency spectra as natural regular patterns. We conclude that new methods are required for quantifying the regularity of spatial patterns beyond a binary classification and to further investigate the difference between natural and model generated patterns.}, language = {en} } @misc{MaurerCaviedesVoulliemeGerkeetal., author = {Maurer, Thomas and Caviedes-Voulli{\`e}me, Daniel and Gerke, Horst H. and Hinz, Christoph}, title = {A 3D-spatial approach for modeling soil hydraulic property distributions on the artificial Huehnerwasser catchment}, series = {Geophysical Research Abstracts}, volume = {21}, journal = {Geophysical Research Abstracts}, pages = {1}, abstract = {Knowledge of catchment 3D spatial heterogeneity is crucial for the assessment and modeling of eco-hydrological processes. Especially during the initial development phase of a hydro-geo-system, the primary structural properties have the potential to determine further development pathways. Small-scale heterogeneity (cm to m scale) may have significant effects on processes on larger spatial scales, but is difficult to measure and quantify. The H{\"u}hnerwasser (Chicken Creek) catchment offers the unique opportunity to study early ecosystem development within an initial structural setup that is well-known, from the plot up to the catchment scale. Based on information on the open-cast mining technology, catchment boundaries and sediment properties, we developed a structure generator program for the process-based modeling of specific dumping structures and sediment property distributions on the catchment. The structure generator reproduces the trajectories of spoil ridges and can be conditioned to reproduce actual sediment distributions according to remote sensing and soil sampling data. Alternatively, sediment distribution scenarios can be generated based on geological data from the excavation site, or can be distributed stochastically. Using pedotransfer functions, the effective hydraulic van-Genuchten parameters are then calculated from sediment texture and bulk density. The main application of the 3D catchment model is to provide detailed 3D-distributed flow domain information for hydrological flow modeling. Observation data are available from catchment monitoring are available for determining the boundary conditions (e.g., precipitation), and the calibration / validation of the model (catchment discharge, ground water). The analysis of multiple sediment distribution scenarios allows to evaluate the effect of initial conditions on hydrological behavior development. Generally, the modeling approach can be used to pinpoint the influx of specific soil structural features on ecohydrological processes across spatial scales.}, language = {en} } @misc{KaestnerCaviedesVoulliemeHinz, author = {K{\"a}stner, Karl and Caviedes-Voulli{\`e}me, Daniel and Hinz, Christoph}, title = {Formation of spatial vegetation patterns in heterogeneous environments}, series = {PLOS One}, volume = {20}, journal = {PLOS One}, number = {5}, editor = {Li, Pan}, publisher = {Public Library of Science (PLoS)}, address = {San Francisco, California}, issn = {1932-6203}, doi = {10.1371/journal.pone.0324181}, pages = {1 -- 38}, abstract = {Functioning of many resource-limited ecosystems is facilitated through spatial patterns. Patterns can indicate ecosystems productivity and resilience, but the interpretation of a pattern requires good understanding of its structure and underlying biophysical processes. Regular patterns are understood to form autogenously through self-organization, for which exogenous heterogeneities are negligible. This has been corroborated by reaction-diffusion models which generate highly regular patterns in idealized homogeneous environments. However, such model-generated patterns are considerably more regular than natural patterns, which indicates that the concept of autogenous pattern formation is incomplete. Models can generate patterns which appear more natural when they incorporate exogenous random spatial heterogeneities (noise), such as microtopography or spatially varying soil properties. However, the mechanism through which noise influences the pattern formation has not been explained so far. Recalling that irregular patterns can form through stochastic processes, we propose that regular patterns can form through stochastic processes as well, where spatial noise is filtered through scale-dependent biophysical feedbacks. First, we demonstrate that the pattern formation in nonlinear reaction-diffusion models is highly sensitive to noise. We then propose simple stochastic processes which can explain why and how random exogenous heterogeneity influences the formation of regular and irregular patterns. Finally, we derive linear filters which reproduce the spatial structure and visual appearance of natural patterns well. Our work contributes to a more holistic understanding of spatial pattern formation in self-organizing ecosystems.}, language = {en} } @misc{CaviedesVoulliemePueyoHinz, author = {Caviedes-Voulli{\`e}me, Daniel and Pueyo, Yolanda and Hinz, Christoph}, title = {Topography and rainfall variability shaping dryland vegetation self-organisation : insights from a numerical modelling study}, series = {Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution}, volume = {264}, journal = {Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0341-8162}, doi = {10.1016/j.catena.2026.109791}, pages = {1 -- 23}, abstract = {The coevolution of hydrological and vegetation dynamics in semi-arid regions often leads to vegetation self-organisation (VSO). While numerous hypotheses on the ecohydrological processes driving VSO have been explored through mathematical models, these have struggled to capture the multiscale complexity emerging from short-term surface runoff over heterogeneous topographies under variable rainfall. This limitation hinders understanding of how natural topography and rainfall variability shape long-term vegetation patterns. Previous studies suggest that intra-storm water redistribution at the hillslope scale - controlled by topography and storm intensity - plays a key role in VSO. However, these factors have rarely been considered together due to methodological constraints in numerical solvers. We argue that accurately representing these processes is essential to investigate their interactions. This study systematically examines the effects of hillslope topography and intra-annual rainfall distributions on vegetation band formation using a physically based model that couples the Zero-Inertia (Diffusive Wave) approximation of the shallow water equations with the HilleRisLambers-Rietkerk vegetation model. Idealised 30-year simulations were conducted at second-scale hydrodynamic resolution across different hillslope forms (plane, convex, concave), slopes, and rainfall regimes along a semi-arid gradient. Results show that both topography and rainfall variability strongly influence band formation through their control on water redistribution and hydrological balance. Steeper slopes enhance runoff over infiltration, reducing water availability and altering band geometry and migration. Concave hillslopes exhibit distinct runoff convergence and redistribution patterns compared to plane or convex slopes. Rainfall intermittency interacts with topography to further affect pattern stability and morphology. While both drivers shape pattern characteristics differently, their joint effects mainly influence band migration without providing a strong stabilising mechanism. These results demonstrate the feasibility of long-term, physically based ecohydrological simulations, paving the way for more comprehensive models including sediment transport and geomorphic feedbacks.}, language = {en} }