Variation of hydro-environment during past four decades with underground sponge city planning to control flash floods in Wuhan, China: An overview

Abstract

This paper presents a review of the variation in the hydro-environment over the past four decades in Wuhan, China, and discusses its close relationship with flash flood events. These flash flood events have inundated underground infrastructures and resulted in significant economic losses and casualties, which are also discussed in relation to various external and internal factors. The external factors are predominantly owing to heavy rainstorms resulting from extreme climate change. The internal factors predominantly include a decrease in wetland areas, changes in topography, and disrepair of drainage systems in urban areas. Since the 1970s, lakes in Wuhan have been significantly reduced in size (by approximately 40%). This reduction in wetland area decreases the water storage capacity in urban areas, and the frequency of large flooding events thus increased from 0.1 event/year to approximately 0.2 event/year. Additionally, the disrepair of drainage systems in urban areas has reduced their ability to resist flood hazards. Changes in topography have also intensified the flood volume per unit time, further burdening the drainage systems. In 2016, Wuhan suffered from several large flooding events that led to some of the most severe economic losses in recorded history. The drainage system at the urban center of Wuhan and proposed flood prevention methods are discussed in detail in this paper. The sponge city (SPC) concept has been attempted in Qingshan District, Wuhan, and its success proved the reliability of the theory. A SPC is believed to reduce the impacts of future flash floods in China and other developed and developing countries.