Linking trends in urban extreme rainfall to urban flooding in China

Abstract

Storm‐induced urban flooding is a global issue that causes large damages and fatalities. Characterizing extreme rainfall is critical to urban flood risk management. Although China's cities have been experiencing a rapid increase in urban flooding in recent decades, there is a lack of national‐wide analysis of the occurrence of extreme urban rainfall. This study examined the trends in extreme rainfall in 146 cities in China for the period 1960–2014. The trends were also analysed in terms of city size (small, big and mega cities) in two city clusters (Jing‐Jin‐Jin City Cluster and Yangtze City Cluster). There was a strong spatial variation in the trends of extreme rainfall across the country, with negative trends in North China and positive trends in Southeast China. Both positive and negative trends were noted for the other regions of China. All the cities in Jing‐Jin‐Ji City Cluster had a decreasing trend in extreme rainfall, with a significant decline (p = 0.03) for mega cities. Then all cities in the Yangtze City Cluster had an increasing trend in extreme rainfall, with a significant increase (p=0.02) for big cities. The findings suggested that efforts to alleviate storm‐induced urban flash floods should take into account both spatial disparities in climate and future changes in extreme rainfall events.

Multiscale Spatio-Temporal Changes of Precipitation Extremes in Beijing-Tianjin-Hebei Region, China during 1958–2017

“…Previous studies have reported that extreme precipitation has changed over the past few decades, but there are apparent discrepancies in regarding these changes over different regions in China, including BTH or North China [73]. Overall, the temporal trends in our work are similar to previous studies in reporting decreasing trends in precipitation extremes over the past few decades in BTH [33,36,40] and the Circum-Bohai-Sea region in the north of China [63,74]. Certainly, there are some discrepancies between our work and previous studies.…”

“…As previous mentioned, changes in precipitation extremes are related to the large-scale circulation change [41,42,[77][78][79]. The periodicity characteristics of precipitation extremes will be helpful to understand their associations or linkages with climate indices, which has been investigated in the other regions in previous studies [40,[60][61][62][63][64][65]. Our results showed that the significant two-to five-year periods at the 5% level were predominant for all the indices during the entire period, which are roughly consistent with the previous work of Wang et al [63].…”

“…The discrepancies may be caused by the data with different time periods used in the two studies. Furthermore, we also analyzed variations of the monthly, seasonal and decadal precipitation extremes, which has been reported in the other regions [64,75,76] but not in the study area [33,36,40]. As all known, North China has a monsoon climate with salient four seasons and about 60-80% of total precipitation amount in summer.…”

Impacts of Land-Use and Land-Cover Changes on Water Yield: A Case Study in Jing-Jin-Ji, China

“…On the other hand, urban flooding events have frequently occurred in recent years, of which the most catastrophic were the "7.21" flood in Beijing city on 21 July 2012 and the "7.19" flood in Xingtai city of Hebei province on 19 July 2016. The region, therefore, is in a situation with a paradoxical coexistence of increased water scarcity and urban flooding [28]. The paradox in the Jing-Jin-Ji region stimulated many hydrological and hydraulic studies, of which the majority focused on the influences of LULC changes on WY at the individual river basin level for the Hai river, Luan river, Miyun reservoir, Chaobai river, and Baiyangdian river [8,[29][30][31][32][33].…”

Nonlinear Trends and Nonstationary Oscillations as Extracted From Annual Accumulated Precipitation at Mexico City

“…In addition to the urban‐induced effect on precipitation, a second man‐induced effect is global warming, which has contributed to the observed precipitation trend in many regions around the world in the last decades (e.g., Armal et al, ; Parr et al, ; Zhou et al, ). It is a difficult task to distinguish between both global warming and urban‐induced contributions to the observed trend in precipitation, as the sources of observational coverage remain sparse, particularly in the tropics.…”