scholarly journals A fractional-order infiltration model to improve the simulation of rainfall/runoff in combination with a 2D shallow water model

2018 ◽  
Vol 20 (4) ◽  
pp. 898-916 ◽  
Author(s):  
J. Fernández-Pato ◽  
J. L. Gracia ◽  
P. García-Navarro
Keyword(s):  
Surface Water ◽  
Fractional Derivative ◽  
Shallow Water ◽  
Fractional Order ◽  
Water Distribution ◽  
Water Model ◽  
Storm Events ◽  
Rainfall Runoff ◽  
Runoff Simulation ◽  
Infiltration Process

Abstract In this work, a distributed two-dimensional (2D) shallow water (SW) flow model is combined with a fractional-order version of the Green-Ampt (FOGA) infiltration law to improve rainfall/runoff simulation in real catchments. The surface water model is based on a robust finite volume method on triangular grids that can handle flow over dry bed and multiple wet/dry fronts. When supplied with adequate infiltration laws, this model can provide useful information in surface hydrology. The classical Green-Ampt law is generalized by using a Caputo fractional derivative of order less than or equal to 1 in Darcy's law. The novelty of this combination is that, on the one hand, the distributed SW simulation provides a detailed surface water distribution and, on the other hand, the FOGA model offers the possibility to model infiltration rates not monotonically decreasing. In order to obtain the best results, a non-uniform order of the fractional derivative depending on the cumulative infiltration and the existence of available surface water is proposed for realistic cases. This allows significant improvement of previous published numerical results in the literature for several storm events in catchments where the infiltration process occurs.

Flash flood simulation using unit hydrograph and hydrodynamic models (case study of Western Caucasus, Russia)

2020 ◽  
Author(s):  
Pelagiya Belyakova ◽  
Ekaterina Vasil'eva ◽  
Andrey Aleksyuk ◽  
Vitaly Belikov ◽  
Boris Gartsman ◽  
...  
Keyword(s):  
Shallow Water ◽  
Monitoring System ◽  
Input Data ◽  
Flash Flood ◽  
Rainfall Runoff ◽  
Western Caucasus ◽  
Unit Hydrograph ◽  
Runoff Simulation ◽  
Flood Simulation ◽  
Flood Monitoring

<p>In the Russian part of Western Caucasus heavy rainfall episodes frequently occur, leading to flash floods that often cause fatalities and severe damage. As soon as climate change is expected to increase the risk of flash floods it is necessary to improve flood forecasting and flood risk mapping as well as other precautionary measures. For this scope the better knowledge of catchment response on heavy precipitation is needed using rainfall-runoff simulation and further hydrodynamic modelling of inundation of urbanized areas.</p><p>There is a number of models used for flash flood simulation. In this study we used an available unit hydrograph model KW-GIUH [1] and a hydrodynamic model STREAM 2D CUDA [2]. KW-GIUH model only schematically describes overland flow over the catchment, nonlinear character of response is introduced via kinematic-wave approximation of the travel time. STREAM 2D CUDA is based on numerical solution of shallow water equations in a two-dimensional formulation according to the original algorithm using the exact solution of the Riemann problem [2], due to which the calculation is performed for the entire catchment without special allocation of the channel network. Models were tested on several flash flood events on the river Adagum (6-7 July 2012, catastrophic flood in the Krymsk town) and the Zapadny Dagomys river (25 June 2015, 24-25 October 2018, Sochi).</p><p>Comparison of simulation results was done as the same input data set was used. Input data included DEM HydroSHEDS, measured hourly precipitation and runoff volumes observed on gauges and estimated after high-water marks. Also 10-min water levels from a regional automated flood monitoring system of the Krasnodar Territory were applied. Simulated runoff volumes and peak timing were analyzed. For the Zapadny Dagomys river a forecasting calculation was done using precipitation forecast from COSMO-Ru. For the Adagum river STREAM 2D CUDA allowed to conduct an experiment to assess possible effect from potential reservoir-traps in the tributaries. The results of the rainfall-runoff simulation by the KW-GIUH model can be used as inflow to the boundary of the area for hydrodynamic modeling using STREAM 2D CUDA, also for operational use. Scenario calculations with changing hydraulic conditions at the catchment can be simulated using the STREAM 2D CUDA model itself.</p><p>The flood simulation was supported by the Russian Science Foundation under grant №17-77-30006. Data processing from an automated flood monitoring system in the Krasnodar Territory is funded by Russian Foundation for Basic Research and the Krasnodar Territory, grant № 19-45-233007.</p><p>References:</p><ol><li>Lee K.T., Cheng N.K., Gartsman B.I., Bugayets A.N. (2009): A current version of the model of a unit hydrograph and its use in Taiwan and Russia, Geography and Natural Resources, Volume 30, issue 1, pp. 79–85. https://doi.org/10.1016/j.gnr.2009.03.015</li> <li>Aleksyuk A.I., Belikov V.V. (2017): Simulation of shallow water flows with shoaling areas and bottom discontinuities, Computational Mathematics and Mathematical Physics, Volume 57, issue 2, pp. 318–339. https://doi.org/10.1134/S0965542517020026</li> </ol>

scholarly journals A coupled atmospheric-hydrologic modeling system with variable grid sizes for rainfall-runoff simulation in semi-humid and semi-arid watersheds: How does the coupling scale affects the results?

2020 ◽  
Author(s):  
Jiyang Tian ◽  
Jia Liu ◽  
Yang Wang ◽  
Wei Wang ◽  
Chuanzhe Li ◽  
...  
Keyword(s):  
Hydrologic Modeling ◽  
Wrf Model ◽  
Northern China ◽  
Flood Forecasting ◽  
Storm Events ◽  
Rainfall Runoff ◽  
Infiltration Capacity ◽  
Runoff Simulation ◽  
Flood Simulation ◽  
Simulation Results

Abstract. The coupled atmospheric-hydrologic modeling system is an effective way in improving the accuracy of rainfall-runoff modeling and extending the lead time in real-time flood forecasting. The aim of this study is to explore the appropriate coupling scale of the coupled atmospheric-hydrologic modeling system, which is established by the Weather Research and Forecasting (WRF) model and the gridded Hebei model with three different sizes (1 × 1 km, 3 × 3 km and 9 × 9 km). The soil moisture storage capacity and infiltration capacity of different grids in the gridded Hebei model are obtained and dispersed using the topographic index. The lumped Hebei model is also used to establish the lumped atmospheric-hydrologic coupled system as a reference system. Four 24 h storm events occurring at two small and medium-scale sub-watersheds in northern China are selected as cases study. Contrastive analyses of the flood process simulations from the gridded and lumped systems are carried out. The results show that the flood simulation results may not always be improved with higher dimension precision and more complicated system, and the grid size selection has a great relationship with the rainfall evenness. For the storm events with uniform spatial distribution, the coupling scale has less impact on flood simulation results, and the lumped system also performs well. For the storm events with uneven spatiotemporal distribution, the corrected rainfall can improve the simulation results significantly, and higher resolution lead to better flood process simulation. The results can help to establish the appropriate coupled atmospheric-hydrologic modeling system to improve the flood forecasting accuracy.

scholarly journals Improved calibration of Green-Ampt infiltration in the EROSION-2D/3D model using a rainfall-runoff experiment database

2020 ◽  
Author(s):  
Hana Beitlerová ◽  
Jonas Lenz ◽  
Jan Devátý ◽  
Martin Mistr ◽  
Jiří Kapička ◽  
...  
Keyword(s):  
Soil Erosion ◽  
3D Model ◽  
Transfer Functions ◽  
Model Performance ◽  
Percentage Error ◽  
Rainfall Runoff ◽  
Soil Infiltration ◽  
Runoff Simulation ◽  
Infiltration Process ◽  
The Impact

Abstract. Soil infiltration is one of the key factors that has an influence on soil erosion caused by rainfall. Therefore, a well-represented infiltration process is a necessary precondition for successful soil erosion modelling. Complex natural conditions do not allow the full mathematical description of the infiltration process and additional calibration parameters are required. The Green-Ampt based infiltration module in the EROSION-2D/3D model is adjusted by calibration of the skinfactor parameter. Previous studies provide skinfactor values for several combinations of soil and vegetation conditions. However, their accuracies are questionable and estimating the skinfactors for other than the measured conditions yields significant uncertainties in the model results. This study presents new empirically based transfer functions for skinfactor estimation that significantly improve the accuracy of the infiltration module and thus the overall EROSION-2D/3D model performance. The transfer functions are based on a statistical analysis of the rainfall-runoff simulation database, which contains 273 experiments compiled by two independent working groups. Linear mixed effects models, with a manual backward elimination approach for the predictor selection, were applied to derive the transfer functions. Soil moisture and bulk density were identified as the most significant predictors explaining 79 % of the skinfactor variability, followed by the soil texture and the impact of previous rainfall events. The mean absolute percentage error of the skinfactor prediction was improved from 192 % using the currently available method, to 66 % using the presented transfer functions. Error propagation of the predicted skinfactors into the surface runoff and soil loss on the hypothetical slope showed significant improvement in the EROSION-2D/3D results. A first validation of real rainfall-runoff events indicates good model performance for events with a higher total precipitation and intensity.

scholarly journals A coupled atmospheric–hydrologic modeling system with variable grid sizes for rainfall–runoff simulation in semi-humid and semi-arid watersheds: how does the coupling scale affects the results?

2020 ◽  
Vol 24 (8) ◽  
pp. 3933-3949 ◽  
Author(s):  
Jiyang Tian ◽  
Jia Liu ◽  
Yang Wang ◽  
Wei Wang ◽  
Chuanzhe Li ◽  
...  
Keyword(s):  
Hydrologic Modeling ◽  
Northern China ◽  
Flood Forecasting ◽  
Storm Events ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Infiltration Capacity ◽  
Runoff Simulation ◽  
Flood Simulation ◽  
Simulation Results

Abstract. The coupled atmospheric–hydrologic modeling system is an effective way to improve the accuracy of rainfall–runoff modeling and extend the lead time in real-time flood forecasting. The aim of this study is to explore the appropriate coupling scale of the coupled atmospheric–hydrologic modeling system, which is established by the Weather Research and Forecasting (WRF) model and the gridded Hebei model with three different sizes (1 km×1 km, 3 km×3 km and 9 km×9 km). The Hebei model is a conceptual rainfall–runoff model designed to describe a mixed runoff generation mechanism, including both storage excess and infiltration excess, in the semi-humid and semi-dry area of northern China. The soil moisture storage capacity and infiltration capacity of different grids in the gridded Hebei model are obtained and dispersed using the topographic index. The lumped Hebei model is also used to establish the lumped atmospheric–hydrologic coupled system as a reference system. Four 24 h storm events occurring at two small- and medium-scale sub-watersheds in northern China are selected as case studies. Contrastive analyses of the flood process simulations from the gridded and lumped systems are carried out. The results show that the flood simulation results may not always be improved with higher-dimension precision and more complicated system, and the grid size selection has a strong relationship with the rainfall evenness. For the storm events with uniform spatial distribution, the coupling scale has less impact on flood simulation results, and the lumped system also performs well. For the storm events with uneven spatiotemporal distribution, the corrected rainfall can improve the simulation results significantly, and higher resolution leads to better flood process simulation. The results can help to establish the appropriate coupled atmospheric–hydrologic modeling system to improve the flood forecasting accuracy.

Investigation of the Green-Ampt infiltration model in rainfall-runoff simulations with a robust 2D shallow water model

2020 ◽  
Author(s):  
Franziska Tügel ◽  
Aziz Hassan ◽  
Manal Wannous ◽  
Uwe Tröger ◽  
Reinhard Hinkelmann
Keyword(s):  
Shallow Water ◽  
Soil Texture ◽  
Laboratory Experiments ◽  
Water Model ◽  
Rainfall Runoff ◽  
Shallow Water Model ◽  
Infiltration Model ◽  
Double Ring ◽  
Infiltration Rates

<p>The Green-Ampt model was developed more than 100 years ago and is still one of the most commonly used approaches to consider infiltration in rainfall-runoff models, which can be either conceptual catchment models as well as 2D hydrodynamic models. When coupling, for example, the Green-Ampt model for infiltration with a 2D shallow water model for the flow, the calculated ponding water depths are transferred from the flow model to the Green-Ampt model to calculate the infiltration rates, and the resulting infiltration rates represent then sinks in the mass balance equation of the shallow water model. The so-called Green-Ampt parameters in terms of saturated water content, hydraulic conductivity, and suction head at the wetting front, are needed as model input in addition to the initial water content. Often, the Green-Ampt parameters are not directly measured in the field for the area that should be modeled but are only assumed based on average values from the literature depending on the dominant soil texture class. If reliable data of certain rainfall-runoff events are available for the study area, the values of the Green-Ampt parameters can be determined besides other calibration parameters within reasonable ranges. However, in some cases, a calibration of the Green-Ampt parameters is not possible due to a lack of measurements, for example during suddenly occurring flash floods or in completely ungauged basins. This study aims to investigate with a coupled shallow water flow and infiltration model if the Green-Ampt parameters could be appropriately assumed based on average values from literature depending on the given soil texture classes. Furthermore, the effects that could lead to an inappropriate representation of infiltration with tabulated Green-Ampt parameters are studied, such as surface clogging, sub-grid rill-flow, and coarse DEM resolution. To investigate the general suitability of using average Green-Ampt parameters from literature dependent on soil texture classes, different small-scale test cases with available data for calibration are shown, where two of them are laboratory experiments and one is a rainfall-runoff experiment on a small plot in Senegal. Finally, a case study on flash floods in a desert region in Egypt is represented. The results show that in the laboratory experiments, the infiltration rates with average Green-Ampt parameters are underestimated, while for the field experiment in Senegal infiltration rates are overestimated. For the case study in Egypt, infiltration with Green-Ampt parameters from literature as well as with measured infiltration rates from double ring infiltrometer tests is strongly overestimated in the model. It is planned to conduct plot-scale rainfall-runoff experiments with a rainfall simulator for the study area in Egypt to better represent the natural conditions during heavy rainfalls and compare the measured infiltration rates with the ones from literature and double ring infiltrometer test.</p>

Correction and preparation of continuously measured raingauge data: a standard method in North Rhine-Westphalia

1998 ◽  
Vol 37 (11) ◽  
pp. 155-162 ◽  
Author(s):  
B. Maul-Kötter ◽  
Th. Einfalt
Keyword(s):  
Water Balance ◽  
Standard Method ◽  
The State ◽  
Rainfall Runoff ◽  
Runoff Simulation ◽  
Site Specific ◽  
Free Data ◽  
Important Input ◽  
Raingauge Data ◽  
Environmental Agency

Continuous raingauge measurements are an important input variable for detailed rainfall-runoff simulation. In North Rhine-Westphalia, more than 150 continuous raingauges are used for local hydrological design through the use of site specific rainfall runoff models. Requiring gap-free data, the State Environmental Agency developed methods to use a combination of daily measurements and neighbouring continuous measurements for filling periods of lacking data in a given raindata series. The objective of such a method is to obtain plausible data for water balance simulations. For more than 3500 station years the described methodology has been applied.

scholarly journals Fractional-Order Colour Image Processing

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 457
Author(s):  
Manuel Henriques ◽  
Duarte Valério ◽  
Paulo Gordo ◽  
Rui Melicio
Keyword(s):  
Image Processing ◽  
Edge Detection ◽  
Fractional Derivative ◽  
Fractional Order ◽  
Fractional Derivatives ◽  
Grey Scale ◽  
Colour Image ◽  
Colour Image Processing ◽  
Image Processing Algorithms ◽  
Processing Algorithms

Many image processing algorithms make use of derivatives. In such cases, fractional derivatives allow an extra degree of freedom, which can be used to obtain better results in applications such as edge detection. Published literature concentrates on grey-scale images; in this paper, algorithms of six fractional detectors for colour images are implemented, and their performance is illustrated. The algorithms are: Canny, Sobel, Roberts, Laplacian of Gaussian, CRONE, and fractional derivative.

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