Merging Top-View Lidar Data With Street-View SFM Data To Enhance Urban Flood Simulation

Top-view data obtainedfrom LiDAR systemshas long been used as topographic-input data for urban flood modelling applications. This high-resolution input data has considerable potential to improve urban flood modelling predictions with more detail. However, the difficulty of employing top-view data is that it may create some missing urban features because this type ofdata cannot represent anyurban features,which are hiddenunderneath other objects. These hidden featuresmay play a substantial part in diverting floodwater flowing through,especially in complex urban areas. The recent advances in Photogrammetry and Computer Vision techniques offer an opportunity to create high-resolution topographic data. By using a consumer digital camera,2Ddigital photoscan betaken from different viewpoints. The so-called Structure from Motion (SfM) techniquecan usethese overlappingphotos and reconstruct theminto3D point-cloud data with a high level of accuracy and resolution,usinga cost effective approach. In this work, we create street-view SfM point-cloud data obtained from street viewpoints. We also introduce a new multi-view approach by merging top-view LiDAR data withstreet-view SfM data. This new multi-view data can be used as topographic input data for a coupled 1D-2D model. When applyingsuch newdata, the flood simulation results can highlight some flood propagations much better than using the traditional top-view LiDAR data. Therefore, it has the potential toenhance the multi-view approach into practicable flood-modelling applications for the present and future urbanizing areas

Modelling sewer discharge via displacement of manhole covers during flood events using 1D/2D SIPSON/P-DWave dual drainage simulations

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordIn urban areas, overloaded sewers may result in surcharge that causes surface flooding. The overflow from sewer systems mainly starts at the inlets until the pressure head in the manhole is high enough to lift up its cover, at which stage the surcharged flow may be discharged via the gap between the bottom of the manhole cover and the ground surface. In this paper, we propose a new approach to simulate such a dynamic between the sewer and the surface flow in coupled surface and sewer flow modelling. Two case studies are employed to demonstrate the differences between the new linking model and the traditional model that simplifies the process. The results show that the new approach is capable of describing the physical phenomena when manhole covers restrict the drainage flow from the surface to the sewer network and reduce the surcharge flow and vice versa.DFG (Deutsche Forschungsgemeinschaft

The urban inundation model with bidirectional flow interaction between 2D overland surface and 1D sewer networks

8th international conference, Novatech 2013, Lyon, France, 23 – 27 June 2013An integrated numerical model is developed in the study for simulating the runoff processes in urban areas. A 1D model is used for calculating the rainfall-runoff hydrographs and the flow conditions in drainage networks. A 2D model is employed for routing flow on overland surface. Both models are solved by different numerical schemes and using different time steps with the flow through manholes adopted as model connections. The effluents and influents via manholes are determined by the weir or the orifice equations. Timing synchronisation between both models is taken into account to guarantee suitable model linkages.EPSRC: Engineering and Physical Sciences Research Counci

Multi-Block Computation for Flood Inundation Studies

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Application of cellular automata approach for fast flood simulation

CCWI 2011: Computing and Control for the Water Industry, 5-7 September 2011, University of Exeter, UKThe increasing pluvial flooding in many urban areas of the world has caused tremendous damage to societies and has drawn the attention of researchers to the development of a fast flood inundation model. Most available models are based on solving a set of partial differential equations that require a huge computational effort. Researchers are increasingly interested in an alternative grid-based approach called Cellular Automata (CA), due to its computational efficiency (both with respect to time and computational cost) and inherent parallel nature. This paper deals with the computational experiment with a new CA method for modelling 2D pluvial flood propagation. A Digital Elevation Model (DEM) comprising square grids forms the discrete space for the CA setup. Local rules are applied in the von Neumann Neighbourhood for the spatio-temporal evolution of the flow field. The proposed model is applied to a hypothetical terrain to assess its performance. The results from the CA model are compared with those of a physically based 2D urban inundation model (UIM). The CA model results are comparable with the results from UIM model. The advantages of low computational cost of CA and its ability to mimic realistic fluid movement are combined in a novel and fast flood simulation model

Formulation of fast 2D urban pluvial flood model using cellular automata approach

Copyright © 2013 IWA Publishing. The definitive peer-reviewed and edited version of this article is published in Journal of Hydroinformatics Vol 15 (3), pp. 676–686 (2013), DOI: 10.2166/hydro.2012.245 and is available at www.iwapublishing.comWith the increase in frequency and severity of flash flood events in major cities around the world, the infrastructure and people living in those urban areas are exposed continuously to high risk levels of pluvial flooding. The situation is likely to be exacerbated by the potential impact of future climate change. A fast flood model could be very useful for flood risk analysis. One-dimensional (1D) models provide limited information about the flow dynamics whereas two-dimensional (2D) models require substantial computational time and cost, a factor that limits their use. This paper presents an alternative approach using cellular automata (CA) for 2D modelling. The model uses regular grid cells as a discrete space for the CA setup and applies generic rules to local neighbourhood cells to simulate the spatio-temporal evolution of pluvial flooding. The proposed CA model is applied to a hypothetical terrain and a real urban area. The synchronous state updating rule and inherent nature of the proposed model contributes to a great reduction in computational time. The results are compared with a hydraulic model and good agreement is found between the two models.Engineering and Physical Sciences Research Council (EPSRC

The application of a GIS-based BMP selection tool for the evaluation of hydrologic performance and storm flow reduction.

A GIS-based BMP tool has been developed within the EU-funded SWITCH project to enable stakeholders to identify appropriate BMPs and their locations to facilitate the control of urban runoff and to reduce the pollutant loads discharged to receiving waters. The attenuation impact of the installed BMPs on separate sewer flows has been predicted by linking this tool to a hydraulic model (STORM). The capability of this combined tool is illustrated using a 4.5 ha section of a city centre development site subjected to measured rainfall data for an extreme storm event. Green roofs and porous paving are used as illustrative examples of BMPs and are shown to have the potential to remove 23-26% and 22-28%, respectively of hourly based flows depending in the incident rainfall volumes. When used in combination, these BMPs have the potential to alleviate exceedance flows in the receiving pipe system. The installation of BMPs is also demonstrated to reduce the short term flow variability caused by rainfall fluctuations and hence to enable planners to more accurately design sewer systems with the required capacity

Exploring new technologies for simulation and analysis of urban flooding

Eng.D ThesisRegulatory drivers, climate change and urbanisation put pressure on urban water managers to find sustainable solutions protecting people and properties from floods now and in the future. For this purpose flood model simulations and analysis are conducted to assess impacts of change on existing systems and to test options for adaptation. Recent developments in hydrodynamic models like CityCAT offer innovative concepts for effective and efficient integrated urban flood modelling. The application of new developments however is met by constraints related to the legacy of established modelling strategies, the modelling tools applied, data availability and the specific duties and responsibilities of stakeholders. The aim of this thesis is to explore new technologies for the simulation and analysis of urban flooding and outline a programme for delivering practical solutions for end-users which addresses these constraints. To address the important practical challenge of missing and inadequate data, a method for generating synthetic networks of storm drain inlets was developed and demonstrated. Tested in fully coupled CityCAT models to link the surface and sub-surface drainage domain, results have shown that synthetic networks of storm drain inlets provide satisfactory results compared with surveyed inlet networks. The results also highlight the sensitivity of the inlet drainage performance related to their location and elevation. Additionally, a generic, open-source flood exposure analysis tool was developed. Detailed hydrodynamic model results and exact building geometries are used to assess the potential internal flooding of buildings for entire cities. Newly developed mapping scripts combine exposure results with hydrodynamic model results to assess cause and consequence of floods. The third part of the thesis presents a strategic-level options appraisal highlighting the practical and financial benefits in relation to a potential industrial application of the new developments. With the availability of open architecture modelling software, this section demonstrates that the model building, simulation and analysis process can be optimised through the application of automated, generic algorithms and cloud computingScottish Water and EPSRC for co-funding

The Value of Urban Flood Modeling

Floods are important disturbances to urban socio-eco-technical systems and their meteorological drivers are projected to increase through the century due to global climate change. Urban flood models are numerical models that have the capability of representing the features of urban ecosystems and the mechanisms of flooding that impact them. They have the potential to play a critical role in flood risk assessment, operational response, and resilience planning, but existing models remain limited in their capability to represent integrated flooding processes in urban areas and provide the credible quantitative information needed to support risk assessment and resilience practice. Research to advance model development, facilitate intensive watershed monitoring for model parameterization and validation, and support collaboration between researchers and practitioners should be prioritized. This will represent a substantial, expensive effort, but will still be of great value as cities are faced with urgent challenges posed by climate change in coming decades