A high resolution coupled hydrologic–hydraulic model (HiResFlood-UCI) for flash flood modeling

Flash Floods are damaging natural hazards which often occur in the European Alps. Precipitation patterns and intensity may change in a future climate affecting their occurrence and magnitude. For impact studies, flash floods can be difficult to simulate due the complex orography and limited extent & duration of the heavy rainfall events which trigger them. The new generation convection-permitting regional climate models improve the intensity and frequency of heavy precipitation (Ban et al., 2021).Therefore, this study combines such simulations with high-resolution distributed hydrological modelling to assess changes in flash flood frequency and occurrence over the Alpine terrain. We use the state-of-the-art Unified Model (Berthou et al., 2018) to drive a high-resolution distributed hydrological wflow_sbm model (e.g. Imhoff et al., 2020) covering most of the Alpine mountain range on an hourly resolution. Simulations of the future climate RCP 8.5 for the end-of-century (2096-2105) and current climate (1998-2007) are compared.First, the wflow_sbm model was validated by comparing ERA5 driven simulation with streamflow observations (across Rhone, Rhine, Po, Adige and Danube). Second, the wflow_sbm simulation driven by UM simulation of the current climate was compared to a dataset of historical flood occurrences (Paprotny et al., 2018, Earth Syst. Sci. Data) to validate if the model can accurately simulate the location of the flash floods and to determine a suitable threshold for flash flooding. Finally, the future run was used to asses changes in flash flood frequency and occurrence. Results show an increase in flash flood frequency for the Upper Rhine and Adige catchments. For the Rhone the increase was less pronounced. The locations where the flash floods occur did not change much.This research is embedded in the EU H2020 project EUCP (EUropean Climate Prediction system) (https://www.eucp-project.eu/), which aims to support climate adaptation and mitigation decisions for the coming decades by developing a regional climate prediction and projection system based on high-resolution climate models for Europe.&#160;N. Ban, E. Brisson, C. Caillaud, E. Coppola, E. Pichelli, S. Sobolowski, &#8230;, M.J. Zander (2021): &#8220;The first multi-model ensemble of regional climate simulations at the kilometer-scale resolution, Part I: Evaluation of precipitation&#8221;, manuscript accepted for publication in Climate Dynamics.S. Berthou, E.J. Kendon, S. C. Chan, N. Ban, D. Leutwyler, C. Sch&#228;r, and G. Fosser, 2018, &#8220;Pan-european climate at convection-permitting scale: a model intercomparison study.&#8221; Climate Dynamics, pages 1&#8211;25, DOI: 10.1007/s00382-018-4114-6Imhoff, R.O., W. van Verseveld, B. van Osnabrugge, A.H. Weerts, 2020. &#8220;Scaling point-scale pedotransfer functions parameter estimates for seamless large-domain high-resolution distributed hydrological modelling: An example for the Rhine river.&#8221; Water Resources Research, 56. Doi: 10.1029/2019WR026807Paprotny, D., Morales Napoles, O., & Jonkman, S. N., 2018. "HANZE: a pan-European database of exposure to natural hazards and damaging historical floods since 1870". Earth System Science Data, 10, 565&#8211;581, https://doi.org/10.5194/essd-10-565-2018

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High resolution simulations of a flash flood near Venice

Natural Hazards and Earth System Science ◽

10.5194/nhess-9-1671-2009 ◽

2009 ◽

Vol 9 (5) ◽

pp. 1671-1678 ◽

Cited By ~ 31

Author(s):

S. Davolio ◽

D. Mastrangelo ◽

M. M. Miglietta ◽

O. Drofa ◽

A. Buzzi ◽

...

Keyword(s):

High Resolution ◽

Flash Flood ◽

Mesoscale Convective System ◽

Early Morning ◽

Venice Lagoon ◽

Precipitation Event ◽

Convective System ◽

Mesoscale Convective ◽

Barrier Type ◽

The Alps

Abstract. During the MAP D-PHASE (Mesoscale Alpine Programme, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) Operational Period (DOP, 1 June–30 November 2007) the most intense precipitation event observed south of the Alps occurred over the Venice Lagoon. In the early morning of 26 September 2007, a mesoscale convective system formed in an area of convergence between a south-easterly low level jet flowing along the Adriatic Sea and a north-easterly barrier-type wind south of the Alps, and was responsible for precipitation exceeding 320 mm in less than 12 h, 240 mm of which in only 3 h. The forecast rainfall fields, provided by several convection resolving models operated daily for the D-PHASE project, have been compared. An analysis of different aspects of the event, such as the relevant mechanisms leading to the flood, the main characteristics of the MCS, and an estimation of the predictability of the episode, has been performed using a number of high resolution, convection resolving models (MOLOCH, WRF and MM5). Strong sensitivity to initial and boundary conditions and to model parameterization schemes has been found. Although low predictability is expected due to the convective nature of rainfall, the forecasts made more than 24 h in advance indicate that the larger scale environment driving the dynamics of this event played an important role in favouring the achievement of a relatively good accuracy in the precipitation forecasts.

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2D hydraulic model integration to real-time flash flood forecasting chain

Comprehensive Flood Risk Management ◽

10.1201/b13715-224 ◽

2012 ◽

Author(s):

C Girard ◽

T Godfroy ◽

M Erlich ◽

E David ◽

C Sorbet ◽

...

Keyword(s):

Real Time ◽

Flash Flood ◽

Flood Forecasting ◽

Hydraulic Model ◽

Model Integration ◽

Flash Flood Forecasting

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Flash flood modeling with the MARINE hydrological distributed model

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-3-3397-2006 ◽

2006 ◽

Vol 3 (6) ◽

pp. 3397-3438 ◽

Cited By ~ 15

Author(s):

V. Estupina-Borrell ◽

D. Dartus ◽

R. Ababou

Keyword(s):

Flash Flood ◽

Distributed Model ◽

Flood Modeling

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Extreme runoff response to short-duration convective rainfall in South-West Germany

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-10739-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 10739-10780

Author(s):

V. Ruiz-Villanueva ◽

M. Borga ◽

D. Zoccatelli ◽

L. Marchi ◽

E. Gaume ◽

...

Keyword(s):

High Resolution ◽

Flash Flood ◽

Rain Gauge ◽

Hydrologic Model ◽

West Germany ◽

Structure Evolution ◽

Model Parameters ◽

Distributed Hydrological Model ◽

Precipitation Frequency ◽

South West

Abstract. The 2 June 2008 flood-producing storm on the Starzel river basin in South-West Germany is examined as a prototype for organized convective systems that dominate the upper tail of the precipitation frequency distribution and are likely responsible for the flash flood peaks in this region. The availability of high-resolution rainfall estimates from radar observations and a rain gauge network, together with indirect peak discharge estimates from a detailed post-event survey, provides the opportunity to study the hydrometeorological and hydrological mechanisms associated with this extreme storm and the ensuing flood. Radar-derived rainfall, streamgauge data and indirect estimates of peak discharges are used along with a distributed hydrologic model to reconstruct hydrographs at multiple locations. The influence of storm structure, evolution and motion on the modeled flood hydrograph is examined by using the "spatial moments of catchment rainfall" (Zoccatelli et al., 2011). It is shown that downbasin storm motion had a noticeable impact on flood peak magnitude. Small runoff ratios (less than 20%) characterized the runoff response. The flood response can be reasonably well reproduced with the distributed hydrological model, using high resolution rainfall observations and model parameters calibrated at a river section which includes most of the area impacted by the storm.

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