Urban adaptive transportation system in extreme precipitation: System dynamic analysis based on Shanghai

Highlights

• The current urban transportation interdependent system has an adaptive structure in regards to extreme precipitation.

• The effects of extreme precipitation on an adaptive urban transportation system can be controlled in long-term prospect.

• The improvement of system adaptability can be achieved through adaptive paths.

Abstract

Extreme precipitation is a major challenge affecting the normal functions of urban transportation, particularly in the context of climate change. National and municipal administrations have responded to the increased probability of extreme precipitation events by expanding drainage facilities, or by warning the public in time. In this study, we applied a dynamic system framework to examine how the interdependent factors in extreme precipitation from engineering and society interact with each other and form an adaptive system. Based on the concept of a complex adaptive system, we identified the adaptive units and paths of the system. We set the model parameters using data from Shanghai, and simulated the dynamic process of the system to 2032. We found that the effects of extreme precipitation on an urban transportation infrastructure can be controlled based on the long-term operation of the adaptive system, and that the adaptive units in the physical, social, and economic subsystems are connected with each other.

Introduction

Cities are high-risk areas for extreme precipitation, and the potential impacts might include damage and losses of infrastructure systems [1]. Intense rainfall can lead to the collapse of urban roads and bridges, and/or the interruption of power and water supplies [2]. Occasionally, intense rainfall can cause more serious and cascading failures. On 21 July 2012, there was an extreme rainfall in Beijing and a vehicle became trapped in a flooded culvert, leading to casualties.

Extreme precipitation has a significant impact on transportation facilities. In the context of urbanisation, urban transportation systems have expanded more than ever, increasing their exposure to heavy rainfalls [3]. Extreme precipitation not only floods paved roads and bridges [4], but also influences underground transport systems [5] and flights. According to the statistics from the Yearbook of Meteorological Disasters in China, there were 40 recorded extreme precipitation events from 2004 to 2016, ranking first among all extreme event types. Of these, 34 events led to urban transportation interruptions, such as road blocking, traffic jams, or subway flooding. Transport disruptions influence the social economy and daily lives of citizens on a large scale [6], demonstrating that urban transportation systems are social assets that are interdependent with other parts of society.

Extreme precipitation appears to be becoming increasingly frequent, and forecasts are hardly accurate all of the time, whether from the news or personal experience. According to an Intergovernmental Panel on Climate Change (IPCC) analysis, the frequency of extreme precipitation will increase in the 21 st century worldwide, owing to global climate change. From 2 June to 12 July 2020, the Central Meteorological Observatory of China issued rainstorm warnings for 40 consecutive days in China. The national average rainfall rose to 172.7 mm, i.e. 12.1 % more than that in the same period in normal years. In addition to the increases in frequency and intensity, the uncertainty and complexity of extreme precipitation cannot be ignored. Considering the high underlying uncertainty and complexity, adaptive conception is often involved during extreme event management, emphasising learning and flexibility.

To cope with the current trend of extreme precipitation, there is an inevitable need to improve the adaptability of urban transportation systems. Adaption is a common term in topics concerned with climate change, and is regarded as another basic strategy concept for addressing climate change and extreme events beyond mitigation. It is used to describe the processes of adjusting to climate change and its impacts [7]. The adaptive system demands a long-term design that emphasises the integration of related components.