TY - GEN A1 - Khosh Bin Ghomash, Shahin A1 - Bachmann, Daniel A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph T1 - Impact of Rainfall Movement on Flash Flood Response: A Synthetic Study of a Semi-Arid Mountainous Catchment T2 - Water N2 - Rainfall is a spatiotemporally varied process and key to accurately capturing catchment runoff and determining flood response. Flash flood response of a catchment can be strongly governed by a rainfall’s spatiotemporal variability and is influenced by storm movement which drives a continuous spatiotemporal change throughout a rainfall event. In this work, the sensitivity of runoff and flooded areas to rainfall movement are assessed in the Kan catchment (Iran). The allochthonous nature of floods in the catchment and how they interact with the effects of rainfall movement are investigated. Fifty synthetic rain hyetographs are generated and traversed over the catchment under different velocities and directions and used to force a 1D/2D hydrodynamic model. The results suggest rainfall movement affects the runoff response in different degrees. Peak discharge, hydrograph shapes and flooded areas are affected. Storms with higher velocities result in higher peaks and faster onsets of runoff and consequently higher flooded areas in comparison to slower storms. The direction of the movement also plays a role. Storms moving along the average direction of the stream result in higher peaks and flooded areas. The relevance of storm direction is greater for slow moving storms. Additionally, the influence of rainfall movement is modulated by hyetograph structure, and the allochthonous behavior is greatly dependent on the location within the drainage network at which it is assessed. KW - storm movement KW - rainfall/runoff simulation KW - runoff generation KW - flash-flood KW - rainfall variability Y1 - 2022 UR - https://www.mdpi.com/2073-4441/14/12/1844 U6 - https://doi.org/10.3390/w14121844 SN - 2073-4441 VL - 14 IS - 12 ER - TY - GEN A1 - Khosh Bin Ghomash, Shahin A1 - Bachmann, Daniel A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph T1 - Storm movement effects on the flash flood response of the Kan catchment T2 - EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022 N2 - Rainfall is a complex, spatial and temporally variated process and one of the core inputs for hydrological and hydrodynamic modelling. Most rainfalls are known to be moving storms with varying directions and velocities. Storm movement is known to be an important influence on runoff generation, both affecting peak discharge and the shape of hydrographs. Therefore, exploring the extent rainfall dynamics affect runoff generation and consequently flooded areas, can be an asset in effective flood risk management. In this work, we study how storm movement (e.g. characterized by velocity and direction) can affect surface flow generation, water levels and flooded areas within a catchment. Moreover, the influence of rainfall temporal variability in correlation with storm movement is taken into account. This is achieved by means of numerical-based, spatially explicit surface flow simulations using the tool ProMaIDes (2021), a free software for risk-based evaluation of flood risk mitigation measures. The storm events are generated using a microcanonical random cascade model and further on trajected across the catchment area. The study area is the Kan river catchment located in the province of Tehran (Iran) with a total area of 836 km², which has experienced multiple flooding events in recent years. Due to its semi-arid climate, steep topography with narrow valleys, this area has high potential for flash flood occurrence as a result of high intensity precipitation. The results of this study show a range of possible magnitudes of influence of rainfall movement on the catchment´s runoff response. The resulting flood maps highlight the importance of rainfall velocity and most importantly the direction of the movement in the estimation of flood events as well as their likelihood in catchment area. Moreover, its shown that the magnitude of influence of storm velocity and direction on discharge strongly depends on the location within the river network which it is measured. Y1 - 2022 U6 - https://doi.org/10.5194/egusphere-egu22-2494 ER - TY - GEN A1 - Khosh Bin Ghomash, Shahin A1 - Bachmann, Daniel A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph T1 - Effects ofWithin-Storm Variability on Allochthonous Flash Flooding: A Synthetic Study T2 - Water N2 - Rainfall is a spatiotemporally variated process and one of the key elements to accurately capture both catchment runoff response and floodplain extents. Flash floods are the result of intense rainfall, typically associated to highly variable rain in both space and time, such as convective storms. In this work, the extent within-storm variability affects runoff and flooding is explored. The Kan catchment (Tehran, Iran) is used as base topography for the simulations. The allochthonous nature of floods in the catchment and how they interact with the effects of storm variability are further investigated. For this, 300 synthetic rainfall signals with different hyetograph variabilities are generated and imposed on a 1D/2D hydrodynamic model. Additionally, a set of simulations with different levels of spatial variability are performed. The results suggest that temporal and spatial variability affect the runoff response in different degrees. Peak discharge and hydrograph shapes, as well as flooded areas, are affected. The effect of storm temporal variability is shown to be significantly higher than storm spatial variability and storm properties such as return period, duration, and volume. Further on the influence of storm spatiotemporal variability on stream discharge and flood response is seen to be strongly dependent on the location within the drainage network at which it is assessed. KW - flash flood KW - rainfall variability KW - rainfall/runoff simulation KW - runoff generation Y1 - 2023 U6 - https://doi.org/10.3390/w15040645 SN - 2073-4441 VL - 15 IS - 4 ER - TY - GEN A1 - Khosh Bin Ghomash, Shahin A1 - Bachmann, Daniel A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph T1 - Introducing a dynamic spatiotemporal rainfall generator for flood risk analysis T2 - EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023 N2 - Precipitation scenario analysis is a crucial step in flood risk assessment, in which storm events with different probabilities are defined and used as input for the hydrological/hydrodynamic calculations. Rainfall generators may serve as a basis for the precipitation analysis. With the increase in the use of high resolution spatially-explicit hydrological/hydrodynamic models in flood risk calculations, demand for synthetic gridded precipitation input is increasing. In this work, we present a dynamic spatiotemporal rainfall generator. The model is capable of generating catchment-scale rainfields containing moving storms, which enable physically-plausible and spatiotemporally coherent precipitation events. This is achieved by the tools event-based approach, where dynamic storms are identified as clusters of related data that occur at different locations in space and time, and are then used as basis for event regeneration. The implemented methodology, mainly inspired by Dierden et al. (2019), provides an improvement in the spatial coherence of precipitation extremes, which can in turn be beneficial in flood risk calculations. The model has been validated under different databases such as the radar-based RADALON dataset or spatially-interpolated historical raingauge timeseries of different catchments in Germany, which is also presented in this work. The validation indicates the models ability to adequately preserve observed storm statistics in the generated timeseries. The generator is developed as an extension to the state-of-the-science flood risk modelling tool ProMaIDes (Promaides 2023). The model also puts great focus on user accessibility with offering features such as an easy installation process, support for most operating systems, a user interface and an online user manual. Y1 - 2023 UR - https://meetingorganizer.copernicus.org/EGU23/EGU23-2599.html UR - https://meetingorganizer.copernicus.org/EGU23/EGU23-2599.html?pdf U6 - https://doi.org/10.5194/egusphere-egu23-2599 ER - TY - GEN A1 - Fernández-Pato, Javier A1 - Caviedes-Voullième, Daniel A1 - García-Navarro, Pilar T1 - Rainfall/runoff simulation with 2D full shallow water equations: Sensitivity analysis and calibration of infiltration parameters T2 - Journal of Hydrology N2 - One of the most difficult issues in the development of hydrologic models is to find a rigorous source of data and specific parameters to a given problem, on a given location that enable reliable calibration. In this paper, a distributed and physically based model (2D Shallow Water Equations) is used for surface flow and runoff calculations in combination with two infiltration laws (Horton and Green–Ampt) for estimating infiltration in a watershed. This technique offers the capability of assigning a local and timedependent infiltration rate to each computational cell depending on the available surface water, soil type or vegetation. We investigate how the calibration of parameters is affected by transient distributed Shallow Water model and the complexity of the problem. In the first part of this work, we calibrate the infiltration parameters for both Horton and Green–Ampt models under flat ponded soil conditions. Then, by means of synthetic test cases, we perform a space-distributed sensitivity analysis in order to show that this calibration can be significantly affected by the introduction of topography or rainfall. In the second part, parameter calibration for a real catchment is addressed by comparing the numerical simulations with two different sets of experimental data, corresponding to very different events in terms of the rainfall volume. We show that the initial conditions of the catchment and the rainfall pattern have a special relevance in the quality of the adjustment. Hence, it is shown that the topography of the catchment and the storm characteristics affect the calibration of infiltration parameters. KW - Finite volumes KW - Shallow-water equations KW - Hydrologic modeling KW - Infiltration models KW - Rain-runoff generation Y1 - 2016 UR - http://dx.doi.org/10.1016/j.jhydrol.2016.03.021 U6 - https://doi.org/10.1016/j.jhydrol.2016.03.021 SN - 0022-1694 VL - 536 SP - 496 EP - 513 ER - TY - CHAP A1 - Caviedes-Voullième, Daniel A1 - Jozefik, Zoltan A1 - Hinz, Christoph T1 - Towards a physically-based multi-scale ecohydrological simulator for semi-arid regions T2 - European Geosciences Union General Assembly 2017 Vienna, Austria, 23–28 April 2017 N2 - The use of numerical models as tools for describing and understanding complex ecohydrological systems has enabled to test hypothesis and propose fundamental, process-based explanations of the system system behaviour as a whole as well as its internal dynamics. Reaction-diffusion equations have been used to describe and generate organized pattern such as bands, spots, and labyrinths using simple feedback mechanisms and boundary conditions. Alternatively, pattern-matching cellular automaton models have been used to generate vegetation self-organization in arid and semi-arid regions also using simple description of surface hydrological processes. A key question is: How much physical realism is needed in order to adequately capture the pattern formation processes in semi-arid regions while reliably representing the water balance dynamics at the relevant time scales? In fact, redistribution of water by surface runoff at the hillslope scale occurs at temporal resolution of minutes while the vegetation development requires much lower temporal resolution and longer times spans. This generates a fundamental spatio-temporal multi-scale problem to be solved, for which high resolution rainfall and surface topography are required. Accordingly, the objective of this contribution is to provide proof-of-concept that governing processes can be described numerically at those multiple scales. The requirements for a simulating ecohydrological processes and pattern formation with increased physical realism are, amongst others: i. high resolution rainfall that adequately captures the triggers of growth as vegetation dynamics of arid regions respond as pulsed systems. ii. complex, natural topography in order to accurately model drainage patterns, as surface water redistribution is highly sensitive to topographic features. iii. microtopography and hydraulic roughness, as small scale variations do impact on large scale hillslope behaviour iv. moisture dependent infiltration as temporal dynamics of infiltration affects water storage under vegetation and in bare soil Despite the volume of research in this field, fundamental limitations still exist in the models regarding the aforementioned issues. Topography and hydrodynamics have been strongly simplified. Infiltration has been modelled as dependent on depth but independent of soil moisture. Temporal rainfall variability has only been addressed for seasonal rain. Spatial heterogenity of the topography as well as roughness and infiltration properties, has not been fully and explicitly represented. We hypothesize that physical processes must be robustly modelled and the drivers of complexity must be present with as much resolution as possible in order to provide the necessary realism to improve transient simulations, perhaps leading the way to virtual laboratories and, arguably, predictive tools. This work provides a first approach into a model with explicit hydrological processes represented by physicallybased hydrodynamic models, coupled with well-accepted vegetation models. The model aims to enable new possibilities relating to spatiotemporal variability, arbitrary topography and representation of spatial heterogeneity, including sub-daily (in fact, arbitrary) temporal variability of rain as the main forcing of the model, explicit representation of infiltration processes, and various feedback mechanisms between the hydrodynamics and the vegetation. Preliminary testing strongly suggests that the model is viable, has the potential of producing new information of internal dynamics of the system, and allows to successfully aggregate many of the sources of complexity. Initial benchmarking of the model also reveals strengths to be exploited, thus providing an interesting research outlook, as well as weaknesses to be addressed in the immediate future. Y1 - 2017 UR - http://meetingorganizer.copernicus.org/EGU2017/EGU2017-14851.pdf N1 - EGU2017-14851 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Caviedes-Voullième, Daniel A1 - Domin, Andrea A1 - Hinz, Christoph T1 - Nonlinear effects of microtopography on macroscopic rainfall-runoff partitioning a the hillslope scale: a modelling study T2 - European Geosciences Union General Assembly 2017 Vienna, Austria, 23–28 April 2017 N2 - The quantitative description and prediction of hydrological response of hillslopes or hillslope-scale catchments to rainfall events is becoming evermore relevant. At the hillslope scale, the onset of runoff and the overall rainfall-runoff transformation are controlled by multiple interacting small-scale processes, that, when acting together produce a response described in terms of hydrological variables well-defined at the catchment and hillslope scales. We hypothesize that small scale features such microtopography of the land surface will will govern large scale signatures of temporal runoff evolution. This can be tested directly by numerical modelling of well-defined surface geometries and adequate process description. It requires a modelling approach consistent with fundamental fluid mechanics, well-designed numerical methods, and computational efficiency. In this work, an idealized rectangular domain representing a hillslope with an idealized 2D sinusoidal microtopography is studied by simulating surface water redistribution by means of a 2D diffusive-wave (zero-inertia) shallow water model. By studying more than 500 surfaces and performing extensive sensitivity analysis forced by a single rainfall pulse, the dependency of characteristic hydrological responses to microtopographical properties was assessed. Despite of the simplicity of periodic surface and the rain event, results indicate complex surface flow dynamics during the onset of runoff observed at the macro and micro scales. Macro scale regimes were defined in terms of characteristics hydrograph shapes and those were related to surface geometry. The reference regime was defined for smooth topography and consisted of a simple hydrograph with smoothly rising and falling limbs with an intermediate steady state. In constrast, rough surface geometry yields stepwise rising limbs and shorter steady states. Furthermore, the increase in total infiltration over the whole domain relative to the smooth reference case shows a strong non-linear dependency on slope and the ratio of the characteristic wavelength and amplitude of microtopography. The coupled analysis of spatial and hydrological results also suggests that the hydrological behaviour can be explained by the spatiotemporal variations triggered by surface connectivity. This study significantly extents previous work on 1D domains, as our results reveal complexities that require 2D representation of the runoff processes. Y1 - 2017 UR - http://meetingorganizer.copernicus.org/EGU2017/EGU2017-8115.pdf N1 - EGU2017-8115 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Maurer, Thomas A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph A1 - Gerke, Horst H. T1 - Dynamik der initialen (öko-) hydrologischen Entwicklung – Modellierung von Anfangsbedingungen und Wasserflüssen in einem exemplarischen Einzugsgebiet T2 - Abstract-Sammlung zu Posterbeiträgen, eingereicht zum Tag der Hydrologie in Trier 2017, 23. 03. – 24. 03. 2017 Y1 - 2017 UR - https://www.uni-trier.de/fileadmin/fb6/prof/PHY/PDF-Dateien/TdH2017_4Abstracts_Poster.pdf SP - S. 20 ER - TY - CHAP A1 - Maurer, Thomas A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph A1 - Gerke, Horst H. T1 - Flow processes on the catchment scale – modeling of initial structural states and hydrological behavior in an artificial exemplary catchment T2 - European Geosciences Union General Assembly 2017 Vienna, Austria, 23–28 April 2017 N2 - Landscapes that are heavily disturbed or newly formed by either natural processes or human activity are in a state of disequilibrium. Their initial development is thus characterized by highly dynamic processes under all climatic conditions. The primary distribution and structure of the solid phase (i.e. mineral particles forming the pore space) is one of the decisive factors for the development of hydrological behavior of the eco-hydrological system and therefore (co-) determining for its – more or less – stable final state. The artificially constructed ‚Hühnerwasser‘ catchment (a 6 ha area located in the open-cast lignite mine Welzow-Süd, southern Brandenburg, Germany) is a landscape laboratory where the initial eco-hydrological development is observed since 2005. The specific formation (or construction) processes generated characteristic sediment structures and distributions, resulting in a spatially heterogeneous initial state of the catchment. We developed a structure generator that simulates the characteristic distribution of the solid phase for such constructed landscapes. The program is able to generate quasi-realistic structures and sediment compositions on multiple spatial levels (1 cm up to ∼ 100 m scale). The generated structures can be i) conditioned to actual measurement values (e.g., soil texture and bulk distribution); ii) stochastically generated, and iii) calculated deterministically according to the geology and technical processes at the excavation site. Results are visualized using the GOCAD software package and the free software Paraview. Based on the 3D-spatial sediment distributions, effective hydraulic van-Genuchten parameters are calculated using pedotransfer functions. The hydraulic behavior of different sediment distribution (i.e. versions or variations of the catchment’s porous body) is calculated using a numerical model developed by one of us (Caviedes-Voullième). Observation data are available from catchment monitoring are available for i) determining the boundary conditions (e.g., precipitation), and ii) the calibration / validation of the model (catchment discharge, ground water). The analysis of multiple sediment distribution scenarios should allow to approximately determine the influx of starting conditions on initial development of hydrological behavior. We present first flow modeling results for a reference (conditioned) catchment model and variations thereof. We will also give an outlook on further methodical development of our approach. Y1 - 2017 UR - http://meetingorganizer.copernicus.org/EGU2017/EGU2017-6639.pdf N1 - EGU2017-6639 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - GEN A1 - Pueyo, Y. A1 - Kéfi, S. A1 - Caviedes-Voullième, Daniel A1 - Fernández-Pato, Javier T1 - Modelling the role of allelopathy on semiarid ecosystems controlled by plant-water feedbacks T2 - XIV MEDECOS & XIII AEET meeting, Human driven scenarios for evolutionary and ecological changes, Abstract book, 31st January - 4th February 2017, Seville, Spain N2 - Plant-plant biotic interactions (i.e. interference and facilitation) are important for the functioning of semi-arid ecosystems. Interference goes beyond competition for resources, and it can involve chemical interactions such as allelopathy. The presence of allelopathy can change the net interaction outcome between plants. For example, allelopathy can be a weapon of an inferior competitor for a limited resource. The output of the biotic interactions between a competitive superior and a competitive inferior plant competing for a limited resource could change if the competitive inferior plant is allelopathic. Moreover, in semiarid ecosystems, vegetation pattern is patchy, and plant establishment occurs predominantly in vegetation patches. Thus, community dynamics are highly dependent on local interactions between plants. Allelopathy could be relevant for plant community dynamics exploiting dynamic and patchy scarce resources, but this mechanism has seldom been explored. We aim to investigate the role of allelopathic interactions on ecosystem dynamics ruled by plant-water feedbacks with a modelling approach to understand its relevance and consequences for semi-arid ecosystems. Allelopathy was included mechanistically, by diffusion of allelopathic compounds with water movements in a spatially-explicit two species model (allelopathic and susceptible plants). We found that the balance between sensitivity to allelopathic compounds and cost of the allelopathic production is key for determining community composition at steady state. Moreover, the range of conditions that presented bistability was widened with the inclusion of allelopathy. These results imply that the ecosystem would be less resilient after perturbations and degraded states could be more stable when allelopathic plants dominate the community. Y1 - 2017 UR - http://www.medecos-aeet-meeting2017.es/ABSTRACT_BOOK_421_p.htm SP - S. 185 PB - Asociación Española de Ecología Terrestre (AEET) CY - Madrid ER -