Probabilistic flood inundation mapping at ungauged streams due to roughness coefficient uncertainty in hydraulic modelling

Papaioannou, George; Vasiliades, Lampros; Λουκάς, Αθανάσιος; Aronica, Giuseppe Tito

doi:10.5194/adgeo-44-23-2017

Cited by 74 publications

(58 citation statements)

References 57 publications

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“…All selected streams drain through the city of Volos and contain multiple hydraulic structures and flood protection works. We point out that the city of Volos has experienced frequent flood events (e.g., 2003,2006,2009,2012) due to heavy precipitation episodes that occurred in the last decades [4,10,25,26,34,35]. In particular, the extreme flash flood event that occurred in October of 2006 involved strong debris flow and mudslides that caused severe impacts on transportation networks, other technical infrastructures and agricultural areas.…”

Section: Study Areamentioning

confidence: 99%

“…One of the basic factors of input data uncertainty in flood inundation modeling and mapping, especially when 2D hydraulic hydrodynamic models are used, is the Digital Elevation Model (DEM) accuracy. The DEM estimation process involves several errors, especially in complex river and riverine areas, due to the topographical technique used [10,25,26,56]. The most common approaches followed for the river and riverine areas topography estimation and the DEM generation are ground surveying topographic approaches and photogrammetric techniques.…”

Section: Hydraulic-hydrodynamic Modellingmentioning

confidence: 99%

“…The two dimensional (2D) HEC-RAS model was developed by the Hydrologic Engineering Center (HEC) of United States Army Corps of Engineers [50] and has been applied in many studies for flood inundation modelling (e.g., [9,10,[25][26][27][51][52][53][54]). Moreover, a benchmark analysis based on the two dimensional modelling capabilities, conducted by the U.S. Army Corps of Engineers, proved that HEC-RAS performed extremely well compared to the leading 2D models [55].…”

Section: Hydraulic-hydrodynamic Modellingmentioning

confidence: 99%

“…Thus, under composite flow conditions, further investigation is needed in the selection of the modelling approach. In such cases, the use of a 2D-modelling approach is generally suggested due to the provision of more accurate or realistic results [10,11,[17][18][19][20][21][22][23][24][25][26]. These models are able to simulate floodplain inundation and river hydraulics, as demonstrated in many studies (e.g., [9,15,[27][28][29][30]).…”

Section: Introductionmentioning

confidence: 99%

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An Operational Method for Flood Directive Implementation in Ungauged Urban Areas

et al. 2018

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An operational framework for flood risk assessment in ungauged urban areas is developed within the implementation of the EU Floods Directive in Greece, and demonstrated for Volos metropolitan area, central Greece, which is frequently affected by intense storms causing fluvial flash floods. A scenario-based approach is applied, accounting for uncertainties of key modeling aspects. This comprises extreme rainfall analysis, resulting in spatially-distributed Intensity-Duration-Frequency (IDF) relationships and their confidence intervals, and flood simulations, through the SCS-CN method and the unit hydrograph theory, producing design hydrographs at the sub-watershed scale, for several soil moisture conditions. The propagation of flood hydrographs and the mapping of inundated areas are employed by the HEC-RAS 2D model, with flexible mesh size, by representing the resistance caused by buildings through the local elevation rise method. For all hydrographs, upper and lower estimates on water depths, flow velocities and inundation areas are estimated, for varying roughness coefficient values. The methodology is validated against the flood event of the 9th October 2006, using observed flood inundation data. Our analyses indicate that although typical engineering practices for ungauged basins are subject to major uncertainties, the hydrological experience may counterbalance the missing information, thus ensuring quite realistic outcomes.

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Section: Study Areamentioning

confidence: 99%

Section: Hydraulic-hydrodynamic Modellingmentioning

confidence: 99%

Section: Hydraulic-hydrodynamic Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Operational Method for Flood Directive Implementation in Ungauged Urban Areas

et al. 2018

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“…The parameter which is under investigation for uncertainty is the Manning coefficients of the catchment, which is quite an important parameter in the simulation [10][11][12]. For the derivation of the training data set, one hundred (100) UHs were derived, adopting the Latin Hypercube Sampling technique for the values of the Manning coefficients.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Roughness Coefficient Uncertainty in Urban Flooding Simulations through a Simplified Methodology

Bellos

Kourtis

Moreno-Rodenas

et al. 2017

Water

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Abstract:A methodology is presented which can be used in the evaluation of parametric uncertainty in urban flooding simulation. Due to the fact that such simulations are time consuming, the following methodology is proposed: (a) simplification of the description of the physical process; (b) derivation of a training data set; (c) development of a data-driven surrogate model; (d) use of a forward uncertainty propagation scheme. The simplification comprises the following steps: (a) unit hydrograph derivation using a 2D hydrodynamic model; (b) calculation of the losses in order to determine the effective rainfall depth; (c) flood event simulation using the principle of the proportionality and superposition. The above methodology was implemented in an urban catchment located in the city of Athens, Greece. The model used for the first step of the simplification was FLOW-R2D, whereas the well-known SWMM software (US Environmental Protection Agency, Washington, DC, USA) was used for the second step of the simplification. For the training data set derivation, an ensemble of 100 Unit Hydrographs was derived with the FLOW-R2D model. The parameters which were modified in order to produce this ensemble were the Manning coefficients in the two friction zones (residential and urban open space areas). The surrogate model used to replicate the unit hydrograph derivation, using the Manning coefficients as an input, was based on the Polynomial Chaos Expansion technique. It was found that, although the uncertainties in the derived results have to be taken into account, the proposed methodology can be a fast and efficient way to cope with dynamic flood simulation in an urban catchment.

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Investigating sea‐state effects on flash flood hydrograph and inundation forecasting

Papaioannou

Varlas

Λουκάς

et al. 2021

Hydrological Processes

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A common source of uncertainty in flood inundation forecasting is the hydrograph used.Given the role of sea-air-hydro-land chain processes on the water cycle, flood hydrographs in coastal areas can be indirectly affected by sea state. This study investigates sea-state effects on precipitation, discharge, and flood inundation forecasting implementing atmospheric, ocean wave, hydrological, and hydraulic-hydrodynamic coupled models. The Chemical Hydrological Atmospheric Ocean wave System (CHAOS) was used for coupled hydro-meteorological-wave simulations 'accounting' or 'not accounting' the impact of sea state on precipitation and, subsequently, on flood hydrograph. CHAOS includes the WRF-Hydro hydrological model and the WRF-ARW meteorological model two-way coupled with the WAM wave model through the OASIS3-MCT coupler. Subsequently, the 2D HEC-RAS hydraulic-hydrodynamic model was forced by the flood hydrographs and map the inundated areas. A flash flood event occurred on 15 November 2017 in Mandra, Attica, Greece, causing 24 fatalities, and damages was selected as case study. The calibration of models was performed exploiting historical flood records and previous studies. Human interventions such as hydraulic works and the urban areas were included in the hydraulic modelling geometry domain.The representation of the resistance caused by buildings was based on Unmanned Aerial System (UAS) data while the local elevation rise method was used in the urban-flood simulation. The flood extent results were assessed using the Critical Success Index (CSI), and CSI penalize. Integrating sea-state affected the forecast of precipitation and discharge peaks, causing up to +24% and from −8% to +36% differences, respectively, improving inundation forecast by 4.5% and flooding additional approximately 70 building blocks. The precipitation forcing time step was also highlighted as significant factor in such a small-scale flash flood. The integrated multidisciplinary methodological approach could be adopted in operational forecasting for civil protection applications facilitating the protection of socio-economic activities and human lives during similar future events.

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Probabilistic flood inundation mapping at ungauged streams due to roughness coefficient uncertainty in hydraulic modelling

Cited by 74 publications

References 57 publications

An Operational Method for Flood Directive Implementation in Ungauged Urban Areas

An Operational Method for Flood Directive Implementation in Ungauged Urban Areas

Quantifying Roughness Coefficient Uncertainty in Urban Flooding Simulations through a Simplified Methodology

Investigating sea‐state effects on flash flood hydrograph and inundation forecasting

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