Using Tabu Search Adjusted with Urban Sewer Flood Simulation to Improve Pluvial Flood Warning via Rainfall Thresholds (original) (raw)
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A review of flood modeling methods for urban pluvial flood application
Modeling Earth Systems and Environment, 2020
Pluvial flood has been increasingly understood as a major threat that has presented a significant risk for many cities worldwide. Regarding flood risk management, flood modeling enables to understand, assess and forecast flood conditions and their impact. Likewise, several hydrodynamic models have been developed and their application has been spread. With respect to effective flood modeling, particularly in urbanized floodplains, the choice of an appropriate method, considering contextual requirements, is challenging. This paper gives an overview of prevailing flood modeling approaches in view of their potentials and limitations for modeling pluvial flood in urban settings. The existing methods are categorized into: rapid flood spreading, one-dimensional sewer, overland flow (1D and 2D), sewer-surface coupling approaches (1D-1D and 1D-2D). Each of these techniques is described, by taking aspects influencing the selection of a proper flood modeling method for a particular application into account. This paper would help urban flood managers, and potential users undertake effective flood modeling tasks, balancing between their needs, model complexity and requirements of both input data and time.
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Increasingly frequent, high-intensity rain events associated with climatic change are driving urban drainage systems to function beyond their design discharge capacity. It has become an urgent issue to mitigate the water resource management challenge. To address this problem, a real-time procedure for predicting the inundation risk in an urban drainage system was developed. The real-time procedure consists of three components: (i) the acquisition and forecast of rainfall data; (ii) rainfall-runoff modeling; and (iii) flood inundation mapping. This real-time procedure was applied to a drainage system in the Sukhumvit area of Bangkok, Thailand, to evaluate its prediction efficacy. The results showed precisely that the present real-time procedure had high predictability in terms of both the water level and flood inundation area mapping. It could also determine hazardous areas with a certain amount of lead time in the drainage system of the Sukhumvit area within an hour of rainfall data...
An Urban Flash Flood Alert Tool for Megacities—Application for Manhattan, New York City, USA
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Urban flooding is a frequent problem affecting cities all over the world. The problem is more significant now that the climate is changing and urbanization trends are increasing. Various, physical hydrological models such as the Environmental Protection Agency Storm Water Management Model (EPA SWMM), MIKE URBAN-II and others, have been developed to simulate flooding events in cities. However, they require high accuracy mapping and a simulation of the underground storm drainage system. Sadly, this capability is usually not available for older or larger so-called megacities. Other hydrological model types are classified in the semi-physical category, like Cellular Automata (CA), require the incorporation of very fine resolution data. These types of data, in turn, demand massive computer power and time for analysis. Furthermore, available forecasting systems provide a way to determine total rainfall during extreme events, but they do not tell us what areas will be flooded. This work in...
Stochastic Environmental Research and Risk Assessment, 2021
This study proposed an equation for Rainfall Threshold for Flood Warning (RTFW) for small urban watersheds based on computer simulations. First, a coupled 1D-2D dual-drainage model was developed for nine watersheds in Seoul, Korea. Next, the model simulation was repeated for a total of 540 combinations of the synthetic rainfall events and watershed imperviousness (9 watersheds x 4 NRCS Curve Number (CN) values x 15 rainfall events). Then, the results of the 101 simulations that caused the critical flooded depth (0.25m-0.35m) were used to develop the equation that relates the value of RTFW to the rainfall event temporal variability (represented as coefficient of variation or CV) and the watershed Curve Number. The results suggest that (1) RTFW exponentially decreases as the rainfall CV increases; (2) RTFW linearly decreases as the watershed CV increases; and that (3) RTFW is dominated by CV when the rainfall has low temporal variability (e.g., CV<0.2) while RTFW is dominated by CN when the rainfall has high temporal variability (e.g., CV>0.4). For validation, the proposed equation was applied for the flood warning system with two storm events occurred in 2010 and 2011 over 239 watersheds in Seoul. The system showed the the hit, false and missed alarm rates at 69% (48%), 31% (52%) and 6.7% (4.5%), respectively for the 2010 (2011) event.
2019
Rafea Al-Suhili 1, Cheila Cullen 1,2* and Reza Khanbilvardi 3 5 1 Civil Engineering Department, NOAA-Crest Center at the City College of New York, NY 10031, USA; 6 ralsuhili@ccny.cuny.edu 7 2 Chemistry, Earth & Environmental Sciences Department, Bronx Community College, New York, NY 8 10479, USA; ccullen@gradcenter.cuny.edu 9 3 Civil Engineering Department, NOAA-Crest Center at the City College of New York, NY 10031, USA; 10 khanbilvardi@ccny.cuny.edu 11 * Correspondence: ccullen@gradcenter.cuny.edu; Tel.: +1-718-289-5569 12 Received: date; Accepted: date; Published: date 13 14 Abstract: Climate change and the world trends on urbanization are driving attention to the urban 15 flooding phenomenon due to its increasing frequency. Available physical models for simulating 16 flooding events such as SWIM, MIKE Urban-II and others of their kind, require the capability of 17 accurately mapping or simulating the underground storm drainage system. Sadly, this capability is 18 usually not ava...
Urban pluvial flooding in Jakarta: applying state-of-the-art technology in a data scarce environment
Water Science and Technology, 2010
Available data relating to major pluvial flooding events in Jakarta, Indonesia were used to investigate the suitability of two different levels of sophistication in urban modelling tools for modelling these events. InfoWorks CS v9.0 was employed to build 1D and 1D/2D models of a 541 ha area of inner city Ciliwung River catchment which has a history of being particularly badly affected by flooding during heavy rainfall events. The study demonstrated that a 1D model was sufficient to simulate the flood extent of a major event using the limited data available. While the 1D/2D model also performed well, more data and time would have been required to match the 1D model's simulation of flood extent. Much more detailed data would have been required to produce reliable results in the 1D/2D model and to enable any kind of verification or calibration of the two models beyond visual comparison with crude flood extent maps.
Journal of Flood Risk Management, 2012
Urban areas are concentrations of flood risk because of the density of development and because they tend to be constructed in low-lying areas. They may be subject to flooding from rivers or the sea but are also vulnerable to the effects of intense direct rainfall, which can overwhelm urban drainage systems, and cause complex and often localised patterns of pluvial flooding. The risk from pluvial flooding is particularly difficult to assess because it is sensitive to the spatialtemporal characteristics of rainfall, local runoff and surface flow processes, the performance of urban drainage systems, and the exact location of buildings. Sampling the variability or uncertainty in all of these processes in order to generate accurate flood risk estimates quickly becomes computationally prohibitive, especially for large urban areas. In this paper, we evaluate alternative approaches for making use of high-resolution spatial-temporal rainfall simulations in urban flood risk analysis. Flood depths are computed with a coupled sewer and surface flood model, and flood damage is estimated using standard depth-damage criteria. Efficient sampling of rainfall events and judicious use of response surfaces that relate rainfall event properties to flood volumes and damages are evaluated and shown to reduce the computational expense of risk analysis by more than 70%. The risk analysis methodology is successfully demonstrated for two contrasting urban locations in the UK.
Water Resources Research, 2019
Recent unprecedented events have highlighted that the existing approach to managing flood risk is inadequate for complex urban systems because of its overreliance on simplistic methods at coarse-resolution large scales, lack of model physicality using loose hydrologic-hydraulic coupling, and absence of urban water infrastructure at large scales. Distributed models are a potential alternative as they can capture the complex nature of these events through simultaneous tracking of hydrologic and hydrodynamic processes. However, their application to large-scale flood mapping and forecasting remains challenging without compromising on spatiotemporal resolution, spatial scale, model accuracy, and local-scale hydrodynamics. Therefore, it is essential to develop techniques that can address these issues in urban systems while maximizing computational efficiency and maintaining accuracy at large scales. This study presents a physically based but computationally efficient approach for large-scale (area > 10 3 km 2) flood modeling of extreme events using a distributed model called Interconnected Channel and Pond Routing. The performance of the proposed approach is compared with a hyperresolution-fixed-mesh model at 60-m resolution. Application of the proposed approach reduces the number of computational elements by 80% and the simulation time for Hurricane Harvey by approximately 4.5 times when compared to the fixed-resolution model. The results show that the proposed approach can simulate the flood stages and depths across multiple gages with a high accuracy (R 2 > 0.8). Comparison with Federal Emergency Management Agency building damage assessment data shows a correlation greater than 95% in predicting spatially distributed flooded locations. Finally, the proposed approach can estimate flood stages directly from rainfall for ungaged streams. Plain Language Summary Climate change and land development or urbanization is expected to exacerbate both the intensity and frequency of extreme flooding worldwide. As the flood severity rises, there is a growing need to develop flood prediction and alert systems that provide fast and reliable forecasts. Currently, it is extremely difficult to identify how much, when, and where the flooding will occur, which can create uncertainty in evacuation planning and preparation. This study proposes a method to improve the urban flood prediction by incorporating more physicality into the numerical flood models, which enables a better estimation of the depth, location, and arrival time of flooding. The graphical elements used to construct the models result in a better representation of the real-world physical features, thereby improving the accuracy of flood simulation. Moreover, the approach presented here also decreases the computation time required to simulate flooding, which is vital for providing timely forecasts. The proposed methods are tested across a large and complex urban system using the rainfall from Hurricane Harvey (2017) and validated using three additional flood events in Texas, United States.
An Evaluation Framework for Urban Pluvial Flooding Based on Open-Access Data
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Identifying the location and estimating the magnitude of urban pluvial flooding events is essential to assess their impacts, particularly in areas where data are unavailable. The present work focused on developing and exemplifying a tool to evaluate urban pluvial flooding based on open-access information. The tool has three separate submodules: (1) sewer network generation and design; (2) hydrodynamic model development; (3) urban pluvial flood evaluation. Application of the first two modules in two catchments and comparison of these results with real data indicated that the tool was able to generate systems with realistic layouts and hydraulic properties. Hydrodynamic models derived from this data were able to simulate realistic flow dynamics. The third module was evaluated for one of the study cases. The results of this indicated that the current approach could be used to identify flood areas and associated flood depths during different rainfall scenarios. The outcomes of this stud...