Development of a new rainfall‐triggering index of flash flood warning‐case study in Yunnan province, China

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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Warning! The use of meteorological information during a flash-flood warning process

Advances in Science and Research ◽

10.5194/asr-3-99-2009 ◽

2009 ◽

Vol 3 (1) ◽

pp. 99-103 ◽

Cited By ~ 7

Author(s):

L. Créton-Cazanave

Keyword(s):

Emergency Services ◽

Flash Flood ◽

Local Population ◽

Flash Floods ◽

Decision Makers ◽

Classical Approach ◽

The Real ◽

Flood Warning ◽

Integrated Studies

Abstract. Warning is a key issue to reduce flash floods impacts. But, despite many studies, local and national authorities still struggle to issue good flash floods warnings. We will argue that this failure results from a classical approach of warnings, based on a strict separation between the assessment world and the action world. We will go further than the previous criticisms (Pielke and Carbone, 2002) and show that forecasters, decision makers, emergency services and local population have quite similar practices during a flash-flood warning. Focusing on the use of meteorological information in the warning process, our case study shows that more research about the real practices of stakeholders would be another step towards integrated studies.

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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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Rainfall Threshold for Flash Flood Early Warning Based on Rational Equation: A Case Study of Zuojiao Watershed in Yunnan Province

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/100/1/012215 ◽

2017 ◽

Vol 100 ◽

pp. 012215

Author(s):

Q Li ◽

Y L Wang ◽

H C Li ◽

M Zhang ◽

C Z Li ◽

...

Keyword(s):

Early Warning ◽

Yunnan Province ◽

Flash Flood ◽

Rainfall Threshold

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

10.20944/preprints202103.0185.v1 ◽

2021 ◽

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 ◽

Available Information

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 is required to issue warn-ings. 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 hours, 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 approach proved potential as an early flood indicator for head-catchments with limited available information.

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