Simulation of the flood evolution process and emergency evacuation process of the Tuanzhou embankment breach

Abstract

[Objective] The efficient execution of emergency evacuation operations is crucial for protecting the lives and property of local residents when a flood occurs. Due to the sudden nature of breach floods and their rapid progression, it is necessary to investigate the impact of flood evolution on the evacuation process. [Methods] The breach flood evacuation process and evolution process of the Tuanzhou embankment in Huarong County were taken as the research object. The Dijkstra algorithm was used to identify emergency evacuation paths for villages within Tuanzhou embankment. The breach flood inundation process, calculated by the ANUGA model, was combined to analyze the impact of flood evolution on the emergency evacuation process. [Results] The simulated water levels from the ANUGA model align closely with the observed water levels, with a Nash efficiency coefficient of 0.97, indicating the model's high accuracy in simulating the flood evolution process following the embankment breach in Tuanzhou embankment. The evacuation route lengths for the main villages in Tuanzhou embankment ranged from 4 to 11 km, with the total evacuation time being exceeded 60 minutes for all routes, and the longest evacuation time being 80.3 minutes. The evacuation routes for villages in the northern part of Tuanzhou embankment were long, resulting in extended travel times. For villages in the central and southern parts, where the population was mainly concentrated near the 055 township road, the vehicle density was higher when the 055 township road was used as the evacuation route, which result ed in reduced road travel speed and increased travel time. Due to the breach being located in the northern part of Tuanzhou embankment, emergency evacuation routes for villages in the central and northern regions were affected by flooding within 2 hours of the embankment breach, while evacuation routes for southern villages began to be inundated approximately 3 hours after the breach. When a 1 hour early warning was issued, all residents in Tuanzhou embankment could be safely evacuated. However, when the early warning was issued 0.5 hours in advance or later, the flood resulted in residents in the northern villages being unable to evacuate successfully. [Conclusion] If a breach occurs at the northern embankment, the villages in the northern part of Tuanzhou embankment will face a higher flood risk, highlighting the urgent need for planning and constructing a safety zone in the northern area of Tuanzhou embankment. The emergency evacuation plans for embankment breach floods in the villages need to be reasonably planned to reduce the decrease in traffic efficiency caused by vehicle congestion and to improve the regional emergency response capability. At the same time, efforts should be made to strengthen the maintenance and inspection of Tuanzhou embankment, as well as to improve disaster perception and early warning capabilities. The findings provide valuable references for flood control and disaster reduction planning, as well as for emergency evacuation of residents in the Tuanzhou embankment.

Keywords

Tuanzhou embankment / embankment breach / flood / emergency evacuation / rainfall / numerical simulation / submerged area / disaster warning