scholarly journals Brief communication: Seismological analysis of flood dynamics and hydrologically-triggered earthquake swarms associated with storm Alex

2021 ◽  
Author(s):  
Małgorzata Chmiel ◽  
Maxime Godano ◽  
Marco Piantini ◽  
Pierre Brigode ◽  
Florent Gimbert ◽  
...  
Keyword(s):  
Template Matching ◽  
Temporal Dynamics ◽  
Flash Flood ◽  
Extreme Rainfall ◽  
Peak Frequency ◽  
Catchment Scale ◽  
Maritime Alps ◽  
Power Peak ◽  
Flood Dynamics ◽  
The Impact

Abstract. On October 2, 2020, the Maritime Alps in southern France were struck by the devastating storm Alex that caused locally more than 600 mm of rain in less than 24 hours. The extreme rainfall and flooding destroyed regional rain and stream gauges. That hinders our understanding of the spatial and temporal dynamics of rainfall-runoff processes during the storm. Here, we show that seismological observations from permanent seismic stations constrain these processes at a catchment scale. The analysis of seismic power, peak frequency, and backazimuth provide us with the timing and velocity of the propagation of flash-flood waves associated with bedload-dominated phases of the flood on the Vésubie river. Moreover, the combined short-term average to long-term average ratio and template matching earthquake detection reveal that 114 local earthquakes between local magnitude ML = −0.5 and ML = 2 were triggered by the hydrological loading and/or the resulting in-situ underground pore pressure increase. This study shows the impact of storm Alex on the Earth’s surface and deep layer processes and paves the way to future works that can reveal further details of these processes.

scholarly journals The 20 February 2010 Madeira flash-floods: synoptic analysis and extreme rainfall assessment

2012 ◽  
Vol 12 (3) ◽  
pp. 715-730 ◽  
Author(s):  
M. Fragoso ◽  
R. M. Trigo ◽  
J. G. Pinto ◽  
S. Lopes ◽  
A. Lopes ◽  
...  
Keyword(s):  
Return Period ◽  
Flash Flood ◽  
Deep Convection ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Rain Gauge ◽  
Reanalysis Data ◽  
Sources Of Information ◽  
Precipitation Records ◽  
Flood Dynamics

Abstract. This study aims to characterise the rainfall exceptionality and the meteorological context of the 20 February 2010 flash-floods in Madeira (Portugal). Daily and hourly precipitation records from the available rain-gauge station networks are evaluated in order to reconstitute the temporal evolution of the rainstorm, as its geographic incidence, contributing to understand the flash-flood dynamics and the type and spatial distribution of the associated impacts. The exceptionality of the rainstorm is further confirmed by the return period associated with the daily precipitation registered at the two long-term record stations, with 146.9 mm observed in the city of Funchal and 333.8 mm on the mountain top, corresponding to an estimated return period of approximately 290 yr and 90 yr, respectively. Furthermore, the synoptic associated situation responsible for the flash-floods is analysed using different sources of information, e.g., weather charts, reanalysis data, Meteosat images and radiosounding data, with the focus on two main issues: (1) the dynamical conditions that promoted such anomalous humidity availability over the Madeira region on 20 February 2010 and (2) the uplift mechanism that induced deep convection activity.

scholarly journals Multi-scale hydrometeorological observation and modelling for flash-flood understanding

2014 ◽  
Vol 11 (2) ◽  
pp. 1871-1945 ◽  
Author(s):  
I. Braud ◽  
P.-A. Ayral ◽  
C. Bouvier ◽  
F. Branger ◽  
G. Delrieu ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Flash Flood ◽  
Spatial Scales ◽  
Regional Scale ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Ungauged Catchments ◽  
The Mediterranean ◽  
Set Up ◽  
The Impact

Abstract. This paper presents a coupled observation and modelling strategy aiming at improving the understanding of processes triggering flash floods. This strategy is illustrated for the Mediterranean area using two French catchments (Gard and Ardèche) larger than 2000 km2. The approach is based on the monitoring of nested spatial scales: (1) the hillslope scale, where processes influencing the runoff generation and its concentration can be tackled; (2) the small to medium catchment scale (1–100 km2) where the impact of the network structure and of the spatial variability of rainfall, landscape and initial soil moisture can be quantified; (3) the larger scale (100–1000 km2) where the river routing and flooding processes become important. These observations are part of the HyMeX (Hydrological Cycle in the Mediterranean Experiment) Enhanced Observation Period (EOP) and lasts four years (2012–2015). In terms of hydrological modelling the objective is to set up models at the regional scale, while addressing small and generally ungauged catchments, which is the scale of interest for flooding risk assessment. Top-down and bottom-up approaches are combined and the models are used as "hypothesis testing" tools by coupling model development with data analyses, in order to incrementally evaluate the validity of model hypotheses. The paper first presents the rationale behind the experimental set up and the instrumentation itself. Second, we discuss the associated modelling strategy. Results illustrate the potential of the approach in advancing our understanding of flash flood processes at various scales.

scholarly journals Hydrological appraisal of operational weather radar rainfall estimates in the context of different modelling structures

2013 ◽  
Vol 10 (8) ◽  
pp. 10495-10534
Author(s):  
D. Zhu ◽  
Y. Xuan ◽  
I. Cluckie
Keyword(s):  
Hydrological Model ◽  
Scale Effects ◽  
Model Performance ◽  
Extreme Rainfall ◽  
Distributed Model ◽  
Catchment Scale ◽  
Radar Rainfall ◽  
Rainfall Events ◽  
The Impact ◽  
Rainfall Estimates

Abstract. Radar rainfall estimates have become increasingly available for hydrological modellers over recent years, especially for flood forecasting and warning over poorly gauged catchments. However, the impact of using radar rainfall as compared with conventional raingauge inputs, with respect to various hydrological model structures, remains unclear and yet to be addressed. In the study presented by this paper, we analysed the flow simulations of the Upper Medway catchment of Southeast England using the UK NIMROD radar rainfall estimates using three hydrological models based upon three very different structures, e.g. a physically based distributed MIKE SHE model, a lumped conceptual model PDM and an event-based unit hydrograph model PRTF. We focused on the sensitivity of simulations in relation to the storm types and various rainfall intensities. The uncertainty in radar-rainfall estimates, scale effects and extreme rainfall were examined in order to quantify the performance of the radar. We found that radar rainfall estimates were lower than raingauge measurements in high rainfall rates; the resolutions of radar rainfall data had insignificant impact at this catchment scale in the case of evenly distributed rainfall events but was obvious otherwise for high-intensity, localised rainfall events with great spatial heterogeneity. As to hydrological model performance, the distributed model had consistent reliable and good performance on peak simulation with all the rainfall types tested in this study.

Geomorphological impact of storm Alex in the Maritime Alps, France: what can we learn from seismological observations?

2021 ◽  
Author(s):  
Małgorzata Chmiel ◽  
Maxime Godano ◽  
Marco Piantini ◽  
Diane Rivet ◽  
Jean-Paul Ampuero ◽  
...  
Keyword(s):  
Template Matching ◽  
Fluid Pressure ◽  
Spatial Dynamics ◽  
Peak Frequency ◽  
Bedload Transport ◽  
Economic Damage ◽  
Maritime Alps ◽  
Ground Shaking ◽  
Transport Dynamics ◽  
Additional Information

<p>On 2-3 October 2020, the Maritime Alps were struck by storm Alex, a violent meteorological event that triggered heavy rainfall in southeast France, more generally referred to as a "Mediterranean Episode". The Mediterranean episode generated cumulative 24-hour rainfall rate locally exceeding yearly averages (>500 mm per 24 hours). The torrential rains triggered hazardous sediment-transporting floods of an intensity never documented in the area causing several casualties, and large infrastructure and economic damage. </p><p>Rain and stream gauges’ measurements during the episode are incomplete and highly uncertain due to threshold saturation and destruction of measuring devices, and changes in the stream bed. However, 11 regional seismological stations of the French permanent network recorded continuous ground shaking during and after the episode. Significant ground unrest was generated by the geomorphological phenomena providing additional information on their temporal and spatial dynamics.</p><p>Here, we present results of the combined efforts in environmental and crustal seismology to better understand the spatiotemporal dynamics of the sediment-transporting floods and hydrological forcing on the solid Earth during and after the episode. For that, we first analyze seismic power, peak frequency, and dominant noise directions of seismic signals generated by sediment-transporting floods to infer bedload transport dynamics. Moreover, by using template matching we detect 93 small earthquakes that were triggered during the Alex episode exactly in the area where rainfall was maximum. This exceptional seismic swarm is possibly triggered by overpressure due to the water load in karsts, or changes in pore fluid pressure. Our results illustrate that seismological observations allow for better understanding and quantifying of the geomorphological impact of extreme weather phenomena in mountainous settings and the related hydro-geomorphological hazards.</p>

Startegic framework for integrated flood Disaster modelling over Bangalore city of India

2021 ◽  
Author(s):  
Smrati Purwar ◽  
Gyanendranath Mohapatra ◽  
Rakesh Vasudevan
Keyword(s):  
Urban Landscape ◽  
Flash Flood ◽  
Warning System ◽  
Extreme Rainfall ◽  
High Elevation ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Bangalore City ◽  
Societal Relevance ◽  
The Impact

<p>Hydro-meteorological disasters, particularly the extreme rainfall events (EREs) and associated flash floods, are very frequent in the major metro cities in India during recent years and in many occasions they cause massive destruction to life and property which in long run make adverse socio-economic impacts over the country. Hence, it makes formost importance and has great societal relevance to modellers working such area to develop an advance prediction system for such disasters in India.A strategic framework combining modelling and data analytics is integral part of developing advanced warning system for preparedness during such disasters. In this study, the role of landuse/landcover like built-up, vegetation, barrenland and waterbodies over the Bangalore city in flash flood occurrence is examined using multispectral spatio-temporal satellite data.The recent LULC map evidences a drastic changes in urban landscape that resulted in loss of natural drainage and waterbeds causing frequent floods. Digital Elevation Map (DEM) is analysed to know the  low-lying and high elevation topography compared with  Mean Sea Level(MSL)to quantify the impact of flooding during Extreme Rainfall Events(ERE) on the different part of the Bangalore city. Using Triangular Irregular Network (TIN), flood simulation is carried out for highland and lowlandarea  to study immediate affected areas during EREs Storm Water Modelling  is carried out for different regions in the city to obtain flood pattern, time and volume during selected EREs. The framework developed and simulation results are very useful in generation of management and mitigation strategy by various user agencies.</p>

scholarly journals Assessing the impact of resolution and soil datasets on flash-flood modelling

2019 ◽  
Vol 23 (3) ◽  
pp. 1801-1818 ◽  
Author(s):  
Alexane Lovat ◽  
Béatrice Vincendon ◽  
Véronique Ducrocq
Keyword(s):  
Land Cover ◽  
Soil Texture ◽  
Flash Flood ◽  
Grid Cell ◽  
Coupled System ◽  
High Water ◽  
Catchment Scale ◽  
Flood Modelling ◽  
Flood Simulations ◽  
The Impact

Abstract. The present study assesses the impacts of two grid resolutions and the descriptors of soil texture and land cover on flash-flood modelling at local and basin scales. The ISBA-TOP coupled system, which is dedicated to Mediterranean flash-flood simulations, is used with two grid-cell sizes (300 and 1000 m), two soil texture datasets, and two land use databases to model 12 past flash-flood events in southeastern France. The skill of the hydrological simulations is assessed using conventional data (discharge measurements from operational networks) and proxy data such as post-event surveys and high-water marks. The results show significant differences between the experiments in terms of both the simulated river discharge and the spatial runoff, whether at the catchment scale or at the local scale. The spatial resolution has the largest impact on the hydrological simulations. In this study, it is also shown that the soil texture has a larger impact on the results than the land cover.

scholarly journals Multi-scale hydrometeorological observation and modelling for flash flood understanding

2014 ◽  
Vol 18 (9) ◽  
pp. 3733-3761 ◽  
Author(s):  
I. Braud ◽  
P.-A. Ayral ◽  
C. Bouvier ◽  
F. Branger ◽  
G. Delrieu ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Flash Flood ◽  
Spatial Scales ◽  
Regional Scale ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Ungauged Catchments ◽  
The Mediterranean ◽  
Set Up ◽  
The Impact

Abstract. This paper presents a coupled observation and modelling strategy aiming at improving the understanding of processes triggering flash floods. This strategy is illustrated for the Mediterranean area using two French catchments (Gard and Ardèche) larger than 2000 km2. The approach is based on the monitoring of nested spatial scales: (1) the hillslope scale, where processes influencing the runoff generation and its concentration can be tackled; (2) the small to medium catchment scale (1–100 km2), where the impact of the network structure and of the spatial variability of rainfall, landscape and initial soil moisture can be quantified; (3) the larger scale (100–1000 km2), where the river routing and flooding processes become important. These observations are part of the HyMeX (HYdrological cycle in the Mediterranean EXperiment) enhanced observation period (EOP), which will last 4 years (2012–2015). In terms of hydrological modelling, the objective is to set up regional-scale models, while addressing small and generally ungauged catchments, which represent the scale of interest for flood risk assessment. Top-down and bottom-up approaches are combined and the models are used as "hypothesis testing" tools by coupling model development with data analyses in order to incrementally evaluate the validity of model hypotheses. The paper first presents the rationale behind the experimental set-up and the instrumentation itself. Second, we discuss the associated modelling strategy. Results illustrate the potential of the approach in advancing our understanding of flash flood processes on various scales.

scholarly journals Hydrological appraisal of operational weather radar rainfall estimates in the context of different modelling structures

2014 ◽  
Vol 18 (1) ◽  
pp. 257-272 ◽  
Author(s):  
D. Zhu ◽  
Y. Xuan ◽  
I. Cluckie
Keyword(s):  
Hydrological Model ◽  
Scale Effects ◽  
Model Performance ◽  
Extreme Rainfall ◽  
Distributed Model ◽  
Catchment Scale ◽  
Radar Rainfall ◽  
Rainfall Events ◽  
The Impact ◽  
Rainfall Estimates

Abstract. Radar rainfall estimates have become increasingly available for hydrological modellers over recent years, especially for flood forecasting and warning over poorly gauged catchments. However, the impact of using radar rainfall as compared with conventional raingauge inputs, with respect to various hydrological model structures, remains unclear and yet to be addressed. In the study presented by this paper, we analysed the flow simulations of the upper Medway catchment of southeast England using the UK NIMROD radar rainfall estimates, using three hydrological models based upon three very different structures (e.g. a physically based distributed MIKE SHE model, a lumped conceptual model PDM and an event-based unit hydrograph model PRTF). We focused on the sensitivity of simulations in relation to the storm types and various rainfall intensities. The uncertainty in radar rainfall estimates, scale effects and extreme rainfall were examined in order to quantify the performance of the radar. We found that radar rainfall estimates were lower than raingauge measurements in high rainfall rates; the resolutions of radar rainfall data had insignificant impact at this catchment scale in the case of evenly distributed rainfall events but was obvious otherwise for high-intensity, localised rainfall events with great spatial heterogeneity. As to hydrological model performance, the distributed model had consistent reliable and good performance on peak simulation with all the rainfall types tested in this study.

scholarly journals Assessing the impact of resolution and soil datasets on flash-flood modelling

2018 ◽  
Author(s):  
Alexane Lovat ◽  
Béatrice Vincendon ◽  
Véronique Ducrocq
Keyword(s):  
Land Cover ◽  
Soil Texture ◽  
Flash Flood ◽  
Grid Cell ◽  
Coupled System ◽  
High Water ◽  
Catchment Scale ◽  
Flood Modelling ◽  
Flood Simulations ◽  
The Impact

Abstract. The present study assesses the impacts of the grid resolution and the descriptors of soil texture and land cover on flash-flood modelling at local and basin scales. The ISBA-TOP coupled system, which is dedicated to Mediterranean flash-flood simulations, is used with two grid-cell sizes (300 m and 1000 m) and various soil datasets to model 12 past flash-flood events in southeastern France. The skill of the hydrological simulations is assessed using conventional data (discharge measurements from operational networks) and proxy data such as post-event surveys and high-water marks. The results show significant differences between the experiments in terms of both the simulated river discharge and the spatial runoff, whether at the catchment scale or at the local scale. The spatial resolution has the largest impact on the hydrological simulations. In this study, it is also shown that the soil texture has a larger impact on the results than the land cover.

scholarly journals Assessment of Rainfall-Induced Landslide Distribution Based on Land Disturbance in Southern Taiwan

2021 ◽  
Vol 10 (4) ◽  
pp. 209
Author(s):  
Chih-Ming Tseng ◽  
Yie-Ruey Chen ◽  
Chwen-Ming Chang ◽  
Yung-Sheng Chue ◽  
Shun-Chieh Hsieh
Keyword(s):  
Satellite Image ◽  
Extreme Rainfall ◽  
Land Area ◽  
Rainfall Events ◽  
Land Disturbance ◽  
Bare Land ◽  
Southern Taiwan ◽  
The Impact ◽  
Landslide Distribution ◽  
The Relationship

This study explores the impact of rainfall on the followed-up landslides after a severe typhoon and the relationship between various rainfall events and the occurrence, scale, and regional characteristics of the landslides, including second landslides. Moreover, the influence of land disturbance was evaluated. The genetic adaptive neural network was used in combination with the texture analysis of the geographic information system for satellite image classification and interpretation to analyze land-use change and retrieve disaster records and surface information after five rainfall events from Typhoon Morakot (2009) to Typhoon Nanmadol (2011). The results revealed that except for extreme Morakot rains, the greater the degree of slope disturbance after rain, the larger the exposed slope. Extreme rainfall similar to Morakot strikes may have a greater impact on the bare land area than on slope disturbance. Moreover, the relationship between the bare land area and the index of land disturbance condition (ILDC) is positive, and the ratio of the bare land area to the quantity of bare land after each rainfall increases with the ILDC. With higher effective accumulative rainfall on the slope in the study area or greater slope disturbance, the landslide area at the second landslide point tended to increase.

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