Modelling Sediment Transport in the disastrous Flash Flood of November 2017 in Mandra (Attica, Greece)  

2021 ◽  
Author(s):  
Vasiliki Sant ◽  
George Mitsopoulos ◽  
Aristides Bloutsos ◽  
Anastasios Stamou
Keyword(s):  
Sediment Transport ◽  
Flash Flood ◽  
Catastrophic Event ◽  
Marine Research ◽  
National Network ◽  
The Third ◽  
Debris Transport ◽  
Sediment Transport Equation ◽  
Analysis System ◽  
General Secretariat

<p> </p><p><strong>Abstract</strong></p><p>The flash flood in Mandra on the 15<sup>th</sup> of November 2017 was the third most disastrous “November” flood in Attica; it was characterized by heavy sediment and debris transport that can be easily observed in Figure 1.</p><p>We applied the Hydrologic Engineering Center's-River Analysis System (HEC-RAS) to model sediment transport using the Ackers-White sediment transport equation that is engraved in HEC-RAS to analyze sediment transport characteristics. The required input data were based on a limited number of available studies, which mainly include a survey performed by the Hellenic Centre for Marine Research in the coastal area of the Elefsis Bay where sediments were deposited after the catastrophic event. We compared the results of the model with calculations performed within a previous Thesis in 2018 using TELEMAC-2D and SISYPHE.</p><p>The present paper is based on the Diploma Thesis of the first author; it was performed within the project “National Network on Climate Change and its Impacts (CLIMPACT)” of the General Secretariat of Research and Technology.</p><p> </p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.5d3d3b91860061319301161/sdaolpUECMynit/12UGE&app=m&a=0&c=bc7fbb3ecf180060dec33436ebc2faea&ct=x&pn=gepj.elif&d=1" alt=""></p><p>Figure 1. The greater area of Mandra (a) before and (b) after the flood event</p>

Ship of the Future

1991 ◽  
Vol 28 (04) ◽  
pp. 197-212
Author(s):  
K. Paetow
Keyword(s):  
Research And Development ◽  
Organizational Structure ◽  
Development Projects ◽  
Main Task ◽  
Focal Points ◽  
Marine Research ◽  
The Third ◽  
Operational Costs ◽  
The Future

In 1980 work began on one of the most intensive and comprehensive marine research and development projects—the German Ship of the Future. The main task was the reduction of the operational costs of a vessel. After five years of work the project was successfully finished with the maiden voyage of the first SdZ prototype ship. The paper describes first the R&D project itself. The organizational structure, the financial background and some examples of development topics are explained. The second part deals with the conversion of the outcomes of the R&D project into the reality of a containership. The third part gives, by example of some focal points of the newly developed ship service technique, a broad description of the HDW-SdZ prototype ships and their economy. A short outlook to further developments concludes the paper.

scholarly journals A hydro-sedimentary modeling system for flash flood propagation and hazard estimation under different agricultural practices

2014 ◽  
Vol 14 (3) ◽  
pp. 625-634 ◽  
Author(s):  
N. N. Kourgialas ◽  
G. P. Karatzas
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Water Depth ◽  
Riparian Vegetation ◽  
Flash Flood ◽  
Flood Hazard ◽  
Hydraulic Modeling ◽  
Modeling Framework ◽  
Mike 11 ◽  
Discharge Velocity

Abstract. A modeling system for the estimation of flash flood flow velocity and sediment transport is developed in this study. The system comprises three components: (a) a modeling framework based on the hydrological model HSPF, (b) the hydrodynamic module of the hydraulic model MIKE 11 (quasi-2-D), and (c) the advection–dispersion module of MIKE 11 as a sediment transport model. An important parameter in hydraulic modeling is the Manning's coefficient, an indicator of the channel resistance which is directly dependent on riparian vegetation changes. Riparian vegetation's effect on flood propagation parameters such as water depth (inundation), discharge, flow velocity, and sediment transport load is investigated in this study. Based on the obtained results, when the weed-cutting percentage is increased, the flood wave depth decreases while flow discharge, velocity and sediment transport load increase. The proposed modeling system is used to evaluate and illustrate the flood hazard for different riparian vegetation cutting scenarios. For the estimation of flood hazard, a combination of the flood propagation characteristics of water depth, flow velocity and sediment load was used. Next, a well-balanced selection of the most appropriate agricultural cutting practices of riparian vegetation was performed. Ultimately, the model results obtained for different agricultural cutting practice scenarios can be employed to create flood protection measures for flood-prone areas. The proposed methodology was applied to the downstream part of a small Mediterranean river basin in Crete, Greece.

Sediment transport equation assessment for selected rivers in Malaysia

2005 ◽  
Vol 3 (3) ◽  
pp. 203-208 ◽  
Author(s):  
Chang Chun Kiat ◽  
Aminuddin Ab. Ghani ◽  
Nor Azazi Zakaria ◽  
Zorkeflee Abu Hasan ◽  
Rozi Abdullah
Keyword(s):  
Sediment Transport ◽  
Transport Equation ◽  
Sediment Transport Equation

scholarly journals Distributed modeling of soil erosion and sediment transport

2018 ◽  
Vol 34 (2) ◽  
pp. 763
Author(s):  
V. HRISSANTHOU ◽  
A. PSILOVIKOS
Keyword(s):  
Sediment Transport ◽  
River Basin ◽  
Sediment Yield ◽  
Surface Erosion ◽  
Rainfall Runoff ◽  
Distributed Modeling ◽  
The Third ◽  
Nestos River ◽  
Under Construction ◽  
The Individual

A mathematical model is used for the estimation of the annual sediment yield resulting from rainfall and runoff at the outlet of Nestos River basin (Toxotes, Thrace, Greece), where the ecologically interesting Nestos delta exists. The model is applied to that part of Nestos River basin (838 km2) which lies downstream of three dams. Two dams (Thissavros and Platanovryssi) have been already constructed, while the third one (Temenos) is under construction. The model consists of three sub-models: a rainfall-runoff sub-model, a surface erosion sub-model and a sediment transport sub-model for streams. This model is also capable of computing the annual erosion amount and sediment yield in the individual sub-basins

scholarly journals Robustness Analysis of Model Parameters for Sediment Transport Equation Development

2019 ◽  
Vol 12 ◽  
pp. 1-17
Author(s):  
Nadiatul Adilah Ahmad Abdul Ghani ◽  
Junaidah Ariffin ◽  
Duratul Ain Tholibon
Keyword(s):  
Sediment Transport ◽  
Transport Equation ◽  
Polynomial Regression ◽  
Robustness Analysis ◽  
Shear Velocity ◽  
Model Parameters ◽  
Evolutionary Polynomial Regression ◽  
Sediment Transport Equation ◽  
Sediment Data ◽  
Influential Parameters

Robustness analysis of model parameters for sediment transport equation development is carried out using 256 hydraulics and sediment data from twelve Malaysian rivers. The model parameters used in the analyses include parameters in equations by Ackers-White, Brownlie, Engelund-Hansen, Graf, Molinas-Wu, Karim-Kennedy, Yang, Ariffin and Sinnakaudan. Seven parameters in five parameter classes were initially tested. Robustness of the model parameters was measured on the statistical relations through Evolutionary Polynomial Regression (EPR) technique and further examined using the discrepancy ratio of the predicted versus the measured values. Results from analyses suggest  (ratio of shear velocity to flow velocity) and  (ratio of hydraulic radius to mean sediment diameter) to be the most significant and influential parameters for the development of sediment transport equation.

scholarly journals Numerical Investigation of a Flash Flood Process that Occurred in Zhongdu River, Sichuan, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingyuan Yang ◽  
Tonghuan Liu ◽  
Jingjing Zhai ◽  
Xiekang Wang
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Flash Flood ◽  
Peak Level ◽  
Field Studies ◽  
Bed Deformation ◽  
Bed Erosion ◽  
Set Up ◽  
Discharge Profile ◽  
The Impact

In 2018, a flash flood occurred in the Zhongdu river, which lies in Yibin, Sichuan province of China. The flood caused many casualties and significant damage to people living nearby. Due to the difficulty in predicting where and when flash floods will happen, it is nearly impossible to set up monitors in advance to detect the floods in detail. Field investigations are usually carried out to study the flood propagation and disaster-causing mechanism after the flood’s happening. The field studies take the relic left by the flash flood to deduce the peak level, peak discharge, bed erosion, etc. and further revel the mechanism between water and sediment transport during the flash flood This kind of relic-based study will generate bigger errors in regions with great bed deformation. In this study, we come up with numerical simulations to investigate the flash flood that happened in the Zhongdu river. The simulations are based on two-dimensional shallow water models coupled with sediment transport and bed deformation models. Based on the real water level and discharge profile measured by a hydrometric station nearby, the numerical simulation reproduced the flash flood in the valley. The results show the flood coverage, water level variation, and velocity distribution during the flood. The simulation offers great help in studying the damage-causing process. Furthermore, simulations without considering sediment transport are also carried out to study the impact of bed erosion and sedimentation. The study proved that, without considering bed deformation, the flood may be greatly underestimated, and the sediment lying in the valley has great impact on flood power.

scholarly journals Application of Python Scripting Techniques for Control and Automation of HEC-RAS Simulations

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1382 ◽  
Author(s):  
Tomasz Dysarz
Keyword(s):  
Sediment Transport ◽  
River Flow ◽  
Data File ◽  
Automatic Calibration ◽  
Sediment Samples ◽  
Python Script ◽  
The Third ◽  
Python Scripting ◽  
Flow And Sediment Transport ◽  
Sediment Data

The purpose of the paper was to present selected techniques for the control of river flow and sediment transport computations with the programming language Python. The base software for modeling of river processes was the well-known and widely used HEC-RAS. The concepts were tested on two models created for a single reach of the Warta river located in the central part of Poland. The ideas described were illustrated with three examples. The first was a basic simulation of a steady flow run from the Python script. The second example presented automatic calibration of model roughness coefficients with Nelder-Mead simplex from the SciPy module. In the third example, the sediment transport was controlled by Python script. Sediment samples were accessed and changed in the sediment data file stored in XML format. The results of the sediment simulation were read from HDF5 files. The presented techniques showed good effectiveness of this approach. The paper compared the developed techniques with other, earlier approaches to control of HEC-RAS computations. Possible further developments were also discussed.

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