Development of a precipitation–area curve for warning criteria of short-duration flash flood

Abstract. This paper presents quantitative criteria for flash flood warning that can be used to rapidly assess flash flood occurrence based on only rainfall estimates. This study was conducted for 200 small mountainous sub-catchments of the Han River basin in South Korea because South Korea has recently suffered many flash flood events. The quantitative criteria are calculated based on flash flood guidance (FFG), which is defined as the depth of rainfall of a given duration required to cause frequent flooding (1–2-year return period) at the outlet of a small stream basin and is estimated using threshold runoff (TR) and antecedent soil moisture conditions in all sub-basins. The soil moisture conditions were estimated during the flooding season, i.e., July, August and September, over 7 years (2002–2009) using the Sejong University Rainfall Runoff (SURR) model. A ROC (receiver operating characteristic) analysis was used to obtain optimum rainfall values and a generalized precipitation–area (P–A) curve was developed for flash flood warning thresholds. The threshold function was derived as a P–A curve because the precipitation threshold with a short duration is more closely related to basin area than any other variables. For a brief description of the P–A curve, generalized thresholds for flash flood warnings can be suggested for rainfall rates of 42, 32 and 20 mm h−1 in sub-basins with areas of 22–40, 40–100 and > 100 km2, respectively. The proposed P–A curve was validated based on observed flash flood events in different sub-basins. Flash flood occurrences were captured for 9 out of 12 events. This result can be used instead of FFG to identify brief flash flood (less than 1 h), and it can provide warning information to decision-makers or citizens that is relatively simple, clear and immediate.

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Development of a Precipitation-Area Curve for Warning Criteria of Short-Duration Flash Flood

10.5194/nhess-2017-213 ◽

2017 ◽

Author(s):

Deg-Hyo Bae ◽

Moon-Hwan Lee ◽

Seun-Keun Moon

Keyword(s):

Soil Moisture ◽

South Korea ◽

Short Duration ◽

Flash Flood ◽

Threshold Function ◽

Flood Events ◽

Small Stream ◽

Flood Warning ◽

Precipitation Area ◽

Moisture Conditions

Abstract. This paper presents quantitative criteria for flash flood warning that can be used to rapidly assess flash flood occurrence based on only rainfall estimates. This study was conducted for 200 small mountainous sub-catchments of the Han River basin in South Korea because South Korea has recently suffered many flash flood events with short duration. Flash Flood Guidance (FFG) was defined as the depth of rainfall of a given duration required to cause minor flooding at the outlet of a small stream basin and was estimated using threshold runoff (TR) and antecedent soil moisture conditions in all the sub-basins. The soil moisture conditions were estimated during the flooding season, i.e., July, August and September, over 7 years (2002~2009) using the Sejong University Rainfall Runoff (SURR) model. A ROC analysis was used to obtain optimum rainfall values and a generalized precipitation-area curve (P-A curve) was developed for flash flood warning thresholds. The threshold function was derived as P-A curve due to the reason that the precipitation threshold with short duration is highly related to basin area than any other variables. Generalized thresholds for flash flood warning were obtained for rainfall rates of 42, 32 and 20 mm/h in sub-basins with areas of 22~40 km2, 40~100 km2 and > 100 km2, respectively. The proposed P-A curve was validated based on actual flash flood events in different sub-basins, which showed the viability of the proposed criteria to capture actual flash floods using only the rainfall rate and area of a sub-basin. The key advantage of this method is possible to issue flash flood warnings without the need to run entire hydro-meteorological model chains in the region where the short-duration flash flood frequently occurred.

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Flash flood warning based on rainfall thresholds and soil moisture conditions: An assessment for gauged and ungauged basins

Journal of Hydrology ◽

10.1016/j.jhydrol.2008.08.023 ◽

2008 ◽

Vol 362 (3-4) ◽

pp. 274-290 ◽

Cited By ~ 204

Author(s):

Daniele Norbiato ◽

Marco Borga ◽

Silvia Degli Esposti ◽

Eric Gaume ◽

Sandrine Anquetin

Keyword(s):

Soil Moisture ◽

Flash Flood ◽

Ungauged Basins ◽

Rainfall Thresholds ◽

Flood Warning ◽

Moisture Conditions

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Rainfall Threshold for Flash Flood Warning Based on Model Output of Soil Moisture: Case Study Wernersbach, Germany

Water ◽

10.3390/w13081061 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1061

Author(s):

Thanh Thi Luong ◽

Judith Pöschmann ◽

Rico Kronenberg ◽

Christian Bernhofer

Keyword(s):

Soil Moisture ◽

Flash Flood ◽

Rainfall Threshold ◽

Probability Of Detection ◽

Water Levels ◽

Critical Success ◽

Flood Warning ◽

Critical Discharge ◽

Critical Success Index

Convective rainfall can cause dangerous flash floods within less than six hours. Thus, simple approaches are required for issuing quick warnings. The flash flood guidance (FFG) approach pre-calculates rainfall levels (thresholds) potentially causing critical water levels for a specific catchment. Afterwards, only rainfall and soil moisture information are required to issue warnings. This study applied the principle of FFG to the Wernersbach Catchment (Germany) with excellent data coverage using the BROOK90 water budget model. The rainfall thresholds were determined for durations of 1 to 24 h, by running BROOK90 in “inverse” mode, identifying rainfall values for each duration that led to exceedance of critical discharge (fixed value). After calibrating the model based on its runoff, we ran it in hourly mode with four precipitation types and various levels of initial soil moisture for the period 1996–2010. The rainfall threshold curves showed a very high probability of detection (POD) of 91% for the 40 extracted flash flood events in the study period, however, the false alarm rate (FAR) of 56% and the critical success index (CSI) of 42% should be improved in further studies. The proposed adjusted FFG approach has the potential to provide reliable support in flash flood forecasting.

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Review of 'Development of a Precipitation-Area Curve for Warning Criteria of Short-Duration Flash Flood' submitted to NHESS by Deg-Hyo Bae, Moon-Hwan Lee, Sung-Keun Moon

10.5194/nhess-2017-213-rc1 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Short Duration ◽

Flash Flood ◽

Precipitation Area ◽

Warning Criteria

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A New Flash Flood Warning Scheme Based on Hydrodynamic Modelling

Water ◽

10.3390/w11061221 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1221 ◽

Cited By ~ 1

Author(s):

Wei Huang ◽

Zhixian Cao ◽

Minghai Huang ◽

Wengang Duan ◽

Yufang Ni ◽

...

Keyword(s):

Flash Flood ◽

Rapid Onset ◽

Disaster Mitigation ◽

Hydrodynamic Modelling ◽

Flood Warning ◽

Mitigation And Adaptation ◽

Critical Rainfall ◽

Moisture Conditions ◽

Flood Flow

Flash flooding is one of the most severe natural hazards and commonly occurs in mountainous and hilly areas. Due to the rapid onset of flash floods, early warnings are critical for disaster mitigation and adaptation. In this paper, a flash flood warning scheme is proposed based on hydrodynamic modelling and critical rainfall. Hydrodynamic modelling considers different rainfall and initial soil moisture conditions. The critical rainfall is calculated from the critical hazard, which is based on the flood flow depth and velocity. After the critical rainfall is calculated for each cell in the catchment, a critical rainfall database is built for flash flood warning. Finally, a case study is presented to show the operating procedure of the new flash flood warning scheme.

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Advances and challenges of the French operational flash flood warning system, Vigicrues Flash

10.5194/egusphere-egu21-16063 ◽

2021 ◽

Author(s):

Julie Demargne ◽

Catherine Fouchier ◽

Didier Organde ◽

Olivier Piotte ◽

Anne Belleudy

Keyword(s):

Hydrological Model ◽

Flash Flood ◽

Warning System ◽

Hydrologic Model ◽

Parameters Estimation ◽

Flood Events ◽

Time Step ◽

Flood Warning ◽

Flood Warning System ◽

High Flood

Since March 2017, the French flash flood warning system, Vigicrues Flash, provides warnings for small-to-medium ungauged basins for about 10,000 municipalities to help emergency services better mitigate potential impacts of ongoing and upcoming flash flood events. Set up by the Ministry in charge of Environment, this system complements flood warnings produced by the Vigicrues procedure for French monitored rivers. Based on a discharge-threshold flood warning method called AIGA, Vigicrues Flash currently ingests radar-gauge rainfall grids at a 1-km resolution into a conceptual distributed rainfall-runoff model. Real-time peak discharge estimated on any river cell are then compared to regionalized flood quantiles (estimated with the same hydrological model). Automated warnings are issued for rivers exceeding the high flood and very high flood thresholds (defined as years of return periods) and for the associated municipalities that might be impacted. This service shares a web platform for the dissemination and communication of early warnings and hazard map displays with the APIC heavy rainfall warning service from M&#233;t&#233;o-France. To better anticipate flash flood events and extend the coverage of the Vigicrues Flash service, the hydrological modeling is being enhanced within the SMASH (Spatially-distributed Modelling and ASsimilation for Hydrology) platform developed by INRAE (formerly Irstea). For the upcoming operational update of Vigicrues Flash, a simplified distributed hydrologic model is continuously run at a 15-minute time step and a 1-km resolution. It includes only 2 parameters per cell, controlling respectively a production reservoir and a transfer reservoir from the G&#233;nie Rural (GR) conceptual models. Cross-validation and regionalization of these two parameters have been improved to better account for basins spatial heterogeneities while optimizing flash flood warning performance. Evaluation results for 921 French basins on the 2007-2019 period show improvements in terms of flash flood event detection and effective warning lead time. Current developments aim to integrate a cell-to-cell routing component and improve parameters estimation at the national scale with the variational calibration schemes recently developed on the SMASH platform by Jay-Allemand et al. (2020). Challenges of including high-resolution precipitation nowcasts and accounting for the hydrometeorological uncertainties via data assimilation and ensemble forecasting are also discussed based on ongoing SMASH research.&#160;Jay-Allemand, M., Javelle, P., Gejadze, I., Arnaud, P., Malaterre, P.-O., Fine, J.-A., and Organde, D.: On the potential of variational calibration for a fully distributed hydrological model: application on a Mediterranean catchment, Hydrol. Earth Syst. Sci., 24, 5519&#8211;5538, https://doi.org/10.5194/hess-24-5519-2020, 2020.

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A multi-sourced assessment of the spatio-temporal dynamic of soil saturation in the MARINE flash flood model

10.5194/hess-2020-311 ◽

2020 ◽

Author(s):

Judith Eeckman ◽

Hélène Roux ◽

Audrey Douinot ◽

Bertrand Bonan ◽

Clément Albergel

Keyword(s):

Soil Moisture ◽

Soil Water ◽

Flash Flood ◽

Soil Column ◽

Soil Layer ◽

Surface Model ◽

Flood Events ◽

Local Soil ◽

Basin Scale ◽

Soil Saturation

Abstract. The MARINE hydrological model is a distributed model dedicated to flash flood simulation. Recent developments of the MARINE model are exploited in this work: on the one hand, formerly relying on water height, transfers of water through the subsurface now take place in a homogeneous soil column based on the volumetric soil water content (SSF model). On the other hand, the soil column is divided into two layers, which represent respectively the upper soil layer and the deep weathered rocks (SSF-DWF model). The aim of the present work is to assess the performances of these new representations for the simulation of soil saturation during flash flood events. An exploration of the various products available in the literature for soil moisture estimation is performed. The performances of the models are estimated with respect to several soil moisture products, either at the local scale or spatially extended: i) The gridded soil moisture product provided by the operational modeling chain SAFRAN-ISBA-MODCOU; ii) The gridded soil moisture product provided by the LDAS-Monde assimilation chain, based on the ISBA-a-gs land surface model and assimilating satellite derived data; iii) the upper soil moisture hourly measurements taken from the SMOSMANIA observation network; iv) The Soil Water Index provided by the Copernicus Global Land Service (CGLS), derived from Sentinel1/C-band SAR and ASCAT satellite data. The case study is performed over two French Mediterranean catchments impacted by flash flood events over the 2017–2019 period. The local comparison of the MARINE outputs with the SMOSMANIA measurements, as well as the comparison at the basin scale of the MARINE outputs with the gridded LDAS-Monde and CGLS data lead to the same conclusions: both the dynamics and the amplitudes of the soil moisture simulated with the SSF and SSF-DWF models are better correlated with both the SMOSMANIA measurements and the LDAS-Monde data than the outputs of the base model. The opportunity of improving the two-layers model calibration is then discussed. In conclusion, the developments presented for the representation of subsurface flow in the MARINE model enhance the soil moisture simulation during flash floods, with respect to both gridded data and local soil moisture measurements.

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Flash floods and debris flow in the city area of Messina, north-east part of Sicily, Italy in October 2009: the case of the Giampilieri catchment

Natural Hazards and Earth System Science ◽

10.5194/nhess-12-1295-2012 ◽

2012 ◽

Vol 12 (5) ◽

pp. 1295-1309 ◽

Cited By ~ 42

Author(s):

G. T. Aronica ◽

G. Brigandí ◽

N. Morey

Keyword(s):

Soil Moisture ◽

Debris Flow ◽

Flash Flood ◽

Flash Floods ◽

Event Analysis ◽

Gis Technology ◽

North East ◽

Temporal And Spatial Variability ◽

Moisture Conditions ◽

The City

Abstract. This paper concerns the analysis of the 1 October 2009 flash flood and debris flow event caused by a very intense rainfall concentrated over the Messina area. The storm caused severe flash floods in many villages around the city of Messina, such as Giampilieri, Scaletta Zanclea, Altolia Superiore and Molino, with 38 casualties and significant damages to property, buildings, roads and bridges estimated close to 550 million Euro. The main focus of this work is to perform a post event analysis, putting together available meteorological and hydrological data in order to get better insight into temporal and spatial variability of the rain storm, the soil moisture conditions and the consequent flash flood in the Giampilieri catchment. The event was investigated using observed data from a raingauge network. Statistical analysis using GEV distribution was performed and rainfall return period (storm severity) was estimated. Further, measured rainfall data and rainfall-runoff modelling were used to estimate soil moisture conditions, to analyse the hydrological behaviour and to reconstruct flood hydrograph. With the help of GIS technology and particularly spatial analysis, the volume of debris which has gone down into the Giampilieri village was also calculated. GIS maps with landslide and material deposit areas were produced and analysed.

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Application of the GPM-IMERG Products in Flash Flood Warning: A Case Study in Yunnan, China

Remote Sensing ◽

10.3390/rs12121954 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1954 ◽

Cited By ~ 1

Author(s):

Meihong Ma ◽

Huixiao Wang ◽

Pengfei Jia ◽

Guoqiang Tang ◽

Dacheng Wang ◽

...

Keyword(s):

Real Time ◽

Yunnan Province ◽

Flash Flood ◽

Tropical Rainfall Measuring Mission ◽

Flood Events ◽

Spatiotemporal Resolution ◽

Flood Warning ◽

Gauge Data ◽

Rti Model ◽

Flood Warnings

NASA’s Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (IMERG) is a major source of precipitation data, having a larger coverage, higher precision, and a higher spatiotemporal resolution than previous products, such as the Tropical Rainfall Measuring Mission (TRMM). However, there rarely has been an application of IMERG products in flash flood warnings. Taking Yunnan Province as the typical study area, this study first evaluated the accuracy of the near-real-time IMERG Early run product (IMERG-E) and the post-real-time IMERG Final run product (IMERG-F) with a 6-hourly temporal resolution. Then the performance of the two products was analyzed with the improved Rainfall Triggering Index (RTI) in the flash flood warning. Results show that (1) IMERG-F presents acceptable accuracy over the study area, with a relatively high hourly correlation coefficient of 0.46 and relative bias of 23.33% on the grid, which performs better than IMERG-E; and (2) when the RTI model is calibrated with the gauge data, the IMERG-F results matched well with the gauge data, indicating that it is viable to use MERG-F in flash flood warnings. However, as the flash flood occurrence increases, both gauge and IMERG-F data capture fewer flash flood events, and IMERG-F overestimates actual precipitation. Nevertheless, IMERG-F can capture more flood events than IMERG-E and can contribute to improving the accuracy of the flash flood warnings in Yunnan Province and other flood-prone areas.

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