Study on the Classification of Urban Waterlogging Rainstorms and Rainfall Thresholds in Cities Lacking Actual Data

Bingyan Ma,Huiliang Wang,Yuan Guo,Zening Wu

doi:10.3390/w12123328

Abstract

Extreme rainfall is the main influencing factor of urban waterlogging. Different types of rainfall often have different characteristics of waterlogging. In order to establish a more accurate urban flood control system, it is necessary to classify waterlogging rainstorms and divide their thresholds. This study proposes a method for applying web crawlers to identify waterlogging rainfall in cities lacking waterlogging observation data and classifying them using the rainfall intensity–duration curves. By selecting appropriate duration thresholds and return period, waterlogging rainstorms are divided into rainfall intensity waterlogging (IW), rainfall amount of waterlogging (AW), combined waterlogging (CW) and no waterlogging (NW). In the application of Zhengzhou City, China, the urban flood control standard and the rainfall time distribution characteristics are used as the basis for the selection of the return period and duration thresholds, and the storm water management model (SWMM) is constructed to simulate the 4 kinds of rainfall characteristics of waterlogging, which is similar to actual situations. It proves that the method is suitable for the classification and thresholds division of different waterlogging rainfall in cities. The results show that the best duration thresholds in Zhengzhou are 20 min (M20) and 60 min (M60), and the best return period standard is 2 a. The thresholds for the 4 types of waterlogging rainstorm are: M20 ≥ 26.47 mm, M60 ≥ 43.80 mm, CW; M20 ≥ 26.47 mm, M60 < 43.80 mm, IW; M20 < 26.47 mm, M60 ≥ 43.80 mm, AW; M20 < 26.47 mm and M60 < 43.80 mm, No waterlogging.

Highlights

In recent years, with the rapid progress of global warming and urbanization, the heat island and rain island effects have concentrated, leading to an increase in extreme rainfall in urban areas [1,2,3,4]
Determining the urban waterlogging rainfall thresholds based on the ID curves with different return periods firstly needs to determine the duration thresholds based on the rainfall characteristics of the study area, and secondly, select the appropriate design rainfall return period based on actual or simulated waterlogging information
Sina Weibo news about urban waterlogging with a large amount of information and high value density are obtained through web crawlers, as a good supplement to urban waterlogging data; according to the quartile relationship between the news volume and the rainfall, waterlogging rainstorms are defined

Summary

Introduction

With the rapid progress of global warming and urbanization, the heat island and rain island effects have concentrated, leading to an increase in extreme rainfall in urban areas [1,2,3,4]. Frequent extreme precipitation events cause urban waterlogging disasters, which seriously affect the lives and property safety of urban residents [5,6]. As the direct driving factor of urban waterlogging disasters, precipitation is the most uncontrolled factor [7,8,9], and analyzing its impact on urban waterlogging is of great significance for exploring the characteristics of urban waterlogging and warning. Many scholars have studied the characteristics of urban floods and waterlogging [10,11]. It can be seen that the amount and intensity of rainfall are two important factors affecting urban waterlogging, waterlogging dominated by two factors often has different characteristics. Studies on rainfall thresholds have found that waterlogging events

Objectives

Methods

Results

Discussion

Conclusion