Establishing an early warning system for flash floods in Hoang Su Phi District, Ha Giang Province, Vietnam

Abstract

Hoang Su Phi is a mountainous district in Ha Giang province, Vietnam. When the rainy season arrives in these parts, flash floods (besides landslides), frequently occur in many areas, seriously affecting the socio‐economic condition of the district. Therefore, in this paper, we have developed an early warning system for flash floods, established based on a geomorphological and hydrological approach. The basic principle underlying this system is the fact that flash floods will often occur where there is high potential risk with sufficient rainfall. In the model, eight parameters of the basin were used to build a potential flash flood map. Using the spatial processing module in an open source software, early predictions from automatic weather stations were interpolated and processed online to produce a potential risk map. Depending on the threshold of precipitation values, the results determined locations where flash flood may occur at various flash flood risk indices (FFRI). The system may be applied to support provision of early flash flood warning up to 1−6 days in advance in the district, allowing the local government ample time to make appropriate decisions on the prevention and/or mitigation of damages caused by flash flood hazards.

Influence of different rainfall patterns and soil water content on hydrological processes in small watersheds

“…Huang et al (2019) proposed a flash flood warning scheme based on hydrodynamics and critical rainfall, which uses designed rainfall, considers different rainfall and initial soil conditions, and establishes a critical rainfall database for flash flood warning, demonstrating a new flash flood warning scheme. Nguyen et al (2019) developed a flash flood warning system based on geomorphological and hydrological methods to address the frequent occurrence of flash floods during the rainy season in Hoang Su Phi, a mountainous district in Ha Giang province, Vietnam. The system classifies rainfall thresholds and provides early flash flood warnings for the area 1-6 days in advance based on different rainfall values, allowing local governments sufficient time to prevent and mitigate losses caused by flash flood.…”