Riverine Flooding and Landfalling Tropical Cyclones Over China

Abstract

Riverine flooding associated with landfalling tropical cyclones (TCs) in the western North Pacific basin is responsible for some of the most severe socioeconomic losses in East Asian countries. However, little is known about the spatial and temporal patterns of TC flooding and its climate controls, which constrain the predictive understandings of flood risk in this highly populated region. We provide a climatological characterization of TC flooding over China based on an exceptional network of stream gauging stations across the entire country. The most extreme floods in central and northeastern China are associated with TCs despite infrequent TC visits in these regions. Temporal variations in TC flooding demonstrate a mixture of controls tied to surface temperature anomalies in the northern hemisphere. The established links between TC flooding and climate controls present a potentially predictive tool of TC flood risk over China and other East Asian countries under future climate conditions.

Climate More Important for Chinese Flood Changes Than Reservoirs and Land Use

“…We analyze the spatial distribution of climate‐induced flood‐generation mechanisms across China and specifically in six hotspots (Figure ). In the coastal areas of eastern China, floods are caused by extreme rainfall associated with landfalling tropical cyclones arriving from the north western Pacific (L. Yang et al., 2020). A little further inland, floods are mainly produced by extreme rainfall associated with weather systems of the East Asian Summer Monsoon (also known as the “Meiyu” front).…”

“…These changes reflect a strong signature of anthropogenic climate change (Burke & Stott, 2017). There is a tendency for a poleward shift of tropical cyclones which has increased their frequency along the northern portion of the coast and thus has increased extreme rainfall (L. Yang et al., 2020). In western China, the wetting trend may be related to the increased water‐holding capacity of the atmosphere and the increase of atmospheric moisture transport from Eurasia to China associated with the southward displacement of the Asian subtropical westerly jet (Peng & Zhou, 2017).…”

The Upper Tail of Flood Peaks Over China: Hydrology, Hydrometeorology, and Hydroclimatology

“…Flood records from these gaging stations are obtained from the Ministry of Water Resources, China, and have been through strict quality-control procedures (by following Chinese hydrologic data compilation code, SL247-1999) to ensure consistency and accuracy of the flood series. A subset of the dataset has been investigated in previous studies (Yang et al, 2019(Yang et al, , 2020. In addition to the systematic stream gaging observations, we comprehensively processed 14,779 miscellaneous flood records from 5,540 flood survey sites across the entire country.…”

“…In addition, China lies at the margin of the northwestern Pacific domain that experiences the most frequent occurrence of tropical cyclones in the world (Peduzzi et al, 2012). Previous studies examine the role of landfalling tropical cyclones in annual flood peaks over China (Yang et al, 2019(Yang et al, , 2020. The August 1975 flood over central China, for example, was induced by typhoon Nina (1975).…”

Climate Leads to Reversed Latitudinal Changes in Chinese Flood Peak Timing

“…This is mainly due to the mixed behaviors of diverse flood‐producing storms (e.g., Yang, Yang, Villarini, et al., 2021). Changes in precipitation over China are associated with the space‐time dynamics of summer monsoon, landfalling tropical cyclones and extratropical synoptic systems (e.g., Tang et al., 2021; Yang et al., 2019, 2020; Zhou et al., 2020). Given the pronounced seasonality of precipitation and the prevalence of rainfall‐runoff floods (e.g., Yang, Yang, Villarini, et al., 2021), it remains elusive to what extent soil moisture can modulate changes in flood peak timing over East Asia.…”