Hierarchical management scheme of urban waterlogging risk based on critical rainfall level: a case study of Xining City

Abstract

With the global climate change and the intensification of human activities, urban waterlogging caused by rainstorm is becoming more prominent, and the problem of urban waterlogging needs to be solved. According to different return periods and drainage standards, a new hierarchical management scheme of urban waterlogging risk is proposed, which is composed of micro source runoff control system, minor drainage transmission system, major waterlogging prevention system and resilience improvment system. Based on long series short duration precipitation data, different critical rainfall levels are calculated considering the relevant drainage and waterlogging prevention standards. The calculation results show that the rainfal level for micro source runoff control system is 15.8mm (i.e. point A). For minor drainage control system, the rainfal level are 20.6 mm and 26.9 mm respectively (i.e. point B and B’). For major waterlogging prevention system, the rainfall level is 53.5mm (i.e. point C). According to these segmentation points, four interconnected urban waterlogging risk management strategies are proposed, i.e. stategy 1.0 focuses on micro scale and aims to promote source runoff control by ‘green infrastructure’, 2.0 focuses on minor scale aims to conduct drainage optimization of ‘grey infrastructure’, 3.0 focuses on major scale aims to improve waterlogging prevention by ‘blue infrastructure’ and 4.0 aims to deal with disaster mitigation by ‘red infrastructure’. Furthermore, the rainfall characteristics, the influence degree of rainfall, and objectives and measures for each stragy are given in detail.