Dynamic Trends of Urban Flooding Mitigation Services in Shenzhen, China

Dihang Xu,Zhiyun Ouyang,Tong Wu,Baolong Han

doi:10.3390/su12114799

Abstract

Urbanization is characterized by population agglomeration and the expansion of impervious land surfaces. As a result of ongoing urbanization, rain and flood events have increasingly affected the well-being of residents in cities across the world. This should draw attention to the role of urban ecosystems in providing runoff retention/flood mitigation services. Focusing on Shenzhen, a major city in southern China, we used a hydrologic model based on the Soil Conservation Service curve number (SCS-CN) model to evaluate this flood reduction ecosystem service and its dynamic trends based on long-term remote sensing data from 1980 to 2018. We find that Shenzhen’s capacity for flood reduction gradually decreased due to changes in land use. The spatial distribution showed strong reduction capacity in the eastern part of the city and weak capacity in the western part. Additionally, the city’s total flood reduction capacity decreased by over 1.88 × 108 m3 over the past two decades. This loss of ecosystem-based flood reduction capacity undermines Shenzhen’s resilience against extreme weather events. Due to climate change, Shenzhen should advance its plan to build a “Sponge City” rooted in the conservation, restoration, and construction of urban ecological spaces.

Highlights

The frequency of urban flooding, the number of people affected by such flooding, and the frequency and intensity of extreme weather events have increased in recent years, likely due to the ongoing effects of global climate change
We focus on a region experiencing one of the most rapid urbanization processes in China since the country’s “Reform and Opening-Up” period began in 1978: the city of Shenzhen in the Pearl River Delta
We evaluated the benefit index for the urban flood mitigation service of Shenzhen city (Figure 7)

Summary

Introduction

The frequency of urban flooding, the number of people affected by such flooding, and the frequency and intensity of extreme weather events have increased in recent years, likely due to the ongoing effects of global climate change. Urbanization has occurred at an even faster rate in China, growing from 36.2% to 58.5% in the years 2000–2017 [5] This makes it important to study the relationships between flood mitigation services, population, and land-use change; this topic is central to understanding how rapidly urbanizing areas should adapt to risks related to climate change. On On March 30, 2014, Shenzhen experienced a period of heavy rainfall later classified as a 50-year flood event. This large but relatively young city, in which more than 13,700 km of sewers had been built, was paralyzed, with more than 200 waterlogged areas [9]

Methods

Results

Discussion

Conclusion