Variation of Hourly Extreme Precipitation in the Three Gorges Reservoir Region, China, from the Observation Record

Abstract

Extreme hourly precipitation is amongst the most prominent driving factors of flash floods and geological disasters. Based on the hourly precipitation data of 35 stations in the Three Gorges Reservoir Region (TGRR) from 1998 to 2020, we analyzed the spatiotemporal variation characteristics of hourly extreme precipitation indexes. The selected indicators included the frequency, intensity, period, annual maximum, trend of hourly heavy precipitation (20–50 mm/h) and hourly extreme heavy precipitation (≥50 mm/h) in the TGRR. Closely related climatic factors such as the Western Pacific Subtropical High Intensity (WPSHI) were also discussed. The results showed that in 2010–2020, the cumulative frequency of heavy precipitation magnitude between 25 and 40 mm/h slightly increased, while the corresponding frequency for magnitudes ≥50 mm/h decreased. In summer, the frequency of both heavy and extreme heavy precipitation increased in June and decreased in August, indicating a shift of extreme events to an earlier time in the flood season. The cumulative frequency of heavy precipitation in July had a period of about 7a, and that of extreme heavy precipitation had a period of 3a. The annual average intensity of heavy precipitation and extreme heavy precipitation in the TGRR was 28.9 mm/h and 61.4 mm/h per station, respectively, and both fluctuated and insignificantly decreased from 1998 to 2020. The annual maximum hourly precipitation center in the TGRR moved downstream from west to northeast. The frequency of heavy precipitation was relatively small along the main stream of the river valley. Both the frequency and total amount of heavy precipitation in southeast of the TGRR were significantly higher than those in other regions. Heavy precipitation in the majority of stations with high elevation (higher than 500 m) showed a decreasing trend. The cumulative frequency of precipitation with an intensity of 20–50 mm/h was closely correlated with the Western Hemisphere Warm Pool (WHWP) Index in February and the WPSHI Index in January, and especially, the abnormal large annual frequency (top 20%) showed strong correlation with the two indexes, implying highly predictable factors for extreme events. The frequency of precipitation intensity above 50 mm/h was correlated with the Western Pacific Warm Pool (WPWP) Area Index in January and the WPWP Intensity Index in November of last year. The research results provide a strong and refined factual basis for the assessment and prediction of extreme precipitation, and for disaster prevention and mitigation, in the TGRR.

Spatial-temporal variations of extreme precipitation indices and their linkage with atmospheric circulation in the middle and lower reaches of the Yangtze River

“…Figure 3. Except for CDD, the spatial distribution of other extreme precipitation indices indicates a downward trend from the southeast to the northwest of the MLYR, consistent with previous researchYang et al, 2021;Zhang et al, 2021). CDD shows a minimum centered over Guizhou and Hunan Province and extends eastward toward the coast.…”

“…The area of the WPSH changed simultaneously with PRCPTOT. There is a significant resonance period between monsoon rainfall (Chaluvadi et al, 2021;Zhang et al, 2021;Zhao et al, 2022). When the intensity of the SCSH is stronger, the precipitation in the MLYR is more likely to increase (Li et al, 2019).…”

Revealing Molecular Level Changes of Dissolved Organic Matter in Black Soils during Continuous Leaching and Their Implications for Drinking Water Treatment

“…The RW0 and SR0 leaching solutions were pumped into the top of the glass columns, respectively, by a peristaltic pump. A flow rate of 1.0 mL/min (∼30 mm/h precipitation) was applied to simulate the case of heavy precipitation/irrigation intensity . To simulate leaching or erosion even after a drought season, the water flow was designed to percolate naturally and pass through the initial dry soil that was not immersed before leaching.…”

“…A flow rate of 1.0 mL/min (∼30 mm/h precipitation) was applied to simulate the case of heavy precipitation/irrigation intensity. 33 To simulate leaching or erosion even after a drought season, the water flow was designed to percolate naturally and pass through the initial dry soil that was not immersed before leaching. Ten samples were collected in ten leaching phases (denoted as P1− P10, respectively), with 100 mL of eluate for each phase.…”

Spatio-Temporal Characteristics and Trend Prediction of Extreme Precipitation—Taking the Dongjiang River Basin as an Example

“…The utilization of the precipitation concentration degree (PCD) and precipitation concentration period (PCP) has become widespread in the investigation of the temporal distribution of precipitation [10,11]. Furthermore, other feature indices, such as the annual maximum precipitation, hourly heavy precipitation (20-50 mm/h), hourly extremely heavy precipitation (≥50 mm/h), daily maximum precipitation, extreme precipitation, and other indicators for 3, 5, or 7 consecutive days have also been frequently adopted to describe and analyze the spatio-temporal variation characteristics of extreme precipitation [12][13][14]. Based on various feature indices of extreme precipitation events, different methods, such as the Mann-Kendall test [15,16], the Student's t test, and the extreme value theory, have been utilized in the investigation of regional extreme precipitation characteristics [17][18][19].…”