Using a 17-site seasonal precipitation reconstruction from a unique historical archive, Yu-Xue-Fen-Cun, the decadal variations of extreme droughts and floods (i.e., the event with occurrence probability of less than 10 % from 1951 to 2000) in North China were investigated, by considering both the probabilities of droughts/floods occurrence in each site and spatial coverage (i.e., percentage of sites). Then, the possible linkages of extreme droughts and floods with ENSO (i.e., El Niño and La Niña) episodes and large volcanic eruptions were discussed. The results show that there were 29 extreme droughts and 28 extreme floods in North China from 1736 to 2000. For most of these extreme drought (flood) events, precipitation decreased (increased) evidently at most of the sites for the four seasons, especially for summer and autumn. But in drought years of 1902 and 1981, precipitation only decreased in summer slightly, while it decreased evidently in the other three seasons. Similarly, the precipitation anomalies for different seasons at different sites also existed in several extreme flood years, such as 1794, 1823, 1867, 1872 and 1961. Extreme droughts occurred more frequently (2 or more events) during the 1770s–1780s, 1870s, 1900s–1930s and 1980s–1990s, among which the most frequent (3 events) occurred in the 1900s and the 1920s. More frequent extreme floods occurred in the 1770s, 1790s, 1820s, 1880s, 1910s and 1950s–1960s, among which the most frequent (4 events) occurred in the 1790s and 1880s. For the total of extreme droughts and floods, they were more frequent in the 1770s, 1790s, 1870s–1880s, 1900s–1930s and 1960s, and the highest frequency (5 events) occurred in the 1790s. A higher probability of extreme drought was found when El Niño occurred in the current year or the previous year. However, no significant connections were found between the occurrences of extreme floods and ENSO episodes, or the occurrences of extreme droughts/floods and large volcanic eruptions.
Extreme climate events, such as droughts and floods, can lead to large
impacts on the natural environment and social system, such as water
resources, agriculture, economic activity and human health and well-being.
Based on the evidence from observed data since 1950, the IPCC (2012) special
report concluded that several regions in the world, particularly southern
Europe and West Africa, have experienced more intense and longer droughts;
however, in central North America and northwestern Australia, droughts have
become either less frequent, less intense or shorter (with medium
confidence). Meanwhile, there have been statistically significant increases
in the number of heavy precipitation events (e.g., 95th percentile) in more
regions than there have been statistically significant decreases over the
world. Furthermore, the strong regional and subregional variations exist in
both extreme drought and heavy precipitation events. For example, in China it
has been shown that droughts appeared more frequently in Northeast China,
North China and the eastern part of Northwest China
during 1961–2013, with persistent, severe and widespread droughts from the
late 1990s to early 2000s. Moreover, severe droughts also became more and
more frequent in Southwest China in the period 2006–2013. However, in the
lower reaches of the Yangtze River and northern Xinjiang, the drought
frequency tended to decrease from 1961 to 2013. Meanwhile, in North China,
the southwest part of Northeast China and the western Sichuan Basin, a
downward trend occurred in yearly rainstorm (i.e.,
However, the instrumental measurements generally covered more than a half century, which cannot represent the full natural climate variability in many regions of the world as those derived from paleoclimate reconstructions, especially drought and flood (e.g., Cook et al., 2010; Ge et al., 2016; IPCC, 2012, 2013). Therefore, investigating variations in extreme climate events from long-term datasets is critical to identify whether the recent extreme events observed by instruments exceed the natural variability, which could provide more experience for adaptation to extremes and disasters in the future (Qin et al., 2015), especially in regions with large precipitation variability and dense population, such as the North China Plain (NCP). This region is located at the margin of the East Asian summer monsoon (EASM) and has a subhumid warm temperate climate with the summer and autumn precipitation accounting for approximately 80 % annual precipitation. As revealed by other studies (e.g., Wang, 2002; Wang and He, 2015; Ding and Wang, 2016), the climate in this region is sensitive to global change and rainfall decreased dramatically from the late 1970s, which had caused the evident impacts on water resources and agriculture when the EASM became weakened.
Recently, there are several studies focusing on the historical severe
drought/flood events in the NCP. For example, based on “A Compendium of
Chinese Meteorological Records of the Last 3000 Years” (Zhang, 2004) and
Zhang (2005) identified 15 severe persistent (
Meanwhile, several studies had argued that the anomalous precipitation in NCP, especially the occurrence of drought, was related to El Niño and large volcanic eruptions. For instance, from the observation data since 1951, it was found that rainfall decreased over northern China (including the NCP and the adjacent areas to the north and west) not only in the summer and autumn of an El Niño-developing year (Wu et al., 2003; Lu, 2005; Zhai et al., 2016) but also in the summer when El Niño decayed (Feng et al., 2014; Zhang et al., 2017). From the document-based reconstruction of yearly dryness/wetness grade for the past 500 years, Chen and Yang (2013) argued that the occurrence of drought in northern China was synchronous with El Niño events in the context of decadal variations. Shen et al. (2007) found that the three most exceptional drought events over eastern China occurred in 1586–1589, 1638–1641 and 1965–1966, with 50 % or more summer rainfall reduction in the droughty centers, which might be triggered by large volcanic eruptions and amplified by the El Niño events.
However, most of these studies were performed from the yearly dryness/wetness grade data and relevant historical descriptions or the limited instrumental period. Therefore, we present a case study, using seasonal precipitation reconstructions, to investigate the variations of extreme drought and flood in the NCP for the past 300 years, which is helpful to understand the impacts of seasonal-scale extreme climate on agriculture and social activities.
Map of the study area and the location of 17 sites with seasonal precipitation reconstruction for 1736–2000.
Three datasets were used in this study, including seasonal precipitation
reconstruction, chronology of El Niño and La Niña events and
chronology of large volcanic eruptions.
Seasonal precipitation reconstruction: it included spring, summer, autumn
and winter precipitation at 17 sites (Fig. 1) located in the NCP
(approximately 34–39 Chronology of El Niño and La Niña events. This chronology was
reconstructed from tree-ring, ice-core, coral records and historical
documents by Gergis and Fowler (2009). There were 119 El Niño and 127
La Niña events identified during 1736–2000. The magnitude of these
El Niño/La Niña events was categorized into five grades as extreme
(E), very strong (VS), strong (S), moderate (M) and weak (W). There are some
other ENSO index reconstructions in the past millennium (e.g., Stahle et al.,
1998; Braganza et al., 2009; McGregor et al., 2010; Wilson et al., 2010; J.
Li et al., 2011, 2013). The reason for our study using the reconstruction by
Gergis and Fowler (2009) is that their result was compiled as a chronology
for each El Niño and La Niña episode rather than the ENSO index;
thus, it is more appropriate for comparison with the extreme drought/flood
event by event. Chronology of large volcanic eruptions. The chronology of large volcanic eruptions
used in this study was extracted from the database of “Volcanoes of
the World” released by the Smithsonian Institution (Global Volcanism
Program, 2013). This dataset includes information on volcano location
(longitude, latitude and elevation), starting and ending dates of eruptive
activity, tephra volume, and volcanic explosivity index (VEI) for each
eruption, in which the VEI is determined by the eruption type and duration,
the tephra volume, and the height of the eruption cloud column. Compared to
the other reconstruction on the volcanic eruptions index (e.g., Sigl et al.,
2015), this chronology contains each volcanic eruption event, which is
convenient to compare with the extreme drought/flood events. It is noted that only
the eruptions with VEI
Percentage of sites with extreme and severe drought/flood that occurred
over North China during 1736–2000. Dashed line: the criteria to identify the
regional extreme drought/flood events. Symbol
Firstly, we calculate the threshold for probability of 10 %, 20 %, 80 % and 90 % occurrence based on the 17-site precipitation reconstruction series according to a gamma distribution, to identify the year when the severe or extreme drought/flood occurred in the period of 1736–2000. For each site, the severe drought (or flood) means that the annual precipitation was lower (or higher) than the threshold for probability of 20 % (or 80 %), and the extreme drought (or flood) was defined as below (or above) the threshold for probability of 10 % (or 90 %). Then, we calculate the percentage of sites with extreme and severe drought (or flood) that occurred in the study area (Fig. 2). It is shown that the top five (i.e., 10 % occurrence) drought events between 1951 and 2000 (i.e., instrumental period) occurred in 1997, 1986, 1965, 1981 and 1991; and the top five flood years were 1964, 1958, 1963, 1956 and 1961 (Fig. 2a). Therefore, we use the minimum percentage of severe and extreme drought (flood) sites among these extreme years in the period 1951–2000, i.e., 35 % (35 %) and 29 % (24 %) of all sites experiencing severe and extreme drought (flood) respectively, as the criteria to identify the regional extreme drought/flood events during 1736–2000 (Fig. 2b).
Furthermore, we compare the extreme drought/flood events with the El Niño/La Niña chronology and the large volcanic eruptions chronology
using the contingency table, to illustrate the characteristics of
connections between extreme drought/flood events, and El Niño/La Niña episodes, and large volcanic eruptions, respectively. For example,
to detect whether the frequency of extreme drought becomes higher in the
years after El Niño events, we create a contingency table by
calculating the numbers of occurrences with extreme drought and El Niño
in the previous year, extreme drought and no El Niño in the previous
year, no extreme drought but El Niño in the previous year, no extreme
drought, and El Niño in the previous year. Then, the chi-square test
(
The box-whisker plot of seasonal precipitation anomaly percentage
among sites for each extreme drought
There were 29 extreme drought events and 28 extreme flood events identified
(Fig. 2) in the period 1736–2000. Extreme drought events occurred in 1743, 1777, 1778,
1783, 1786, 1792, 1805, 1813, 1847, 1856, 1869, 1876, 1877, 1900, 1901, 1902,
1916, 1919, 1920, 1922, 1927, 1936, 1939, 1941, 1965, 1981, 1986, 1991 and
1997. Extreme flood events occurred in 1742, 1751, 1774, 1776, 1794, 1797,
1798, 1799, 1800, 1822, 1823, 1830, 1858, 1867, 1872, 1882, 1883, 1886, 1889,
1890, 1910, 1914, 1937, 1956, 1958, 1961, 1963 and 1964. Figure 3 illustrates
the box-whisker plot of seasonal precipitation anomaly percentage among 17
sites for each extreme drought and flood event. It is shown that for a
majority of extreme drought (flood) events, precipitation decreased
(increased) evidently at most of sites for the four seasons, especially for
summer and autumn, because the precipitation in summer and autumn accounts
for approximately 60 % and 20 % of the annual precipitation,
respectively. For example, in the extreme drought year of 1877, the regional
precipitation anomaly (i.e., referenced to the average of all sites over
the entire study area relative to the mean precipitation of all years) was
Compared to the extreme droughts and floods reported in previous studies
(Chen and Yang, 2013; Hao et al., 2010a, b; Shen et al., 2007, 2008; Zhang,
2005; Zheng et al., 2006), our results identified a majority of extreme
drought years and 10 extreme flood years (i.e., 1751, 1800, 1822, 1823, 1883,
1889, 1937, 1956, 1963 and 1964) in their publications. Moreover, our results
revealed 9 extreme drought events and 18 extreme flood events (marked
The frequency of extreme drought and flood in North China for each decade from 1740s to 1990s.
Figure 4 illustrates the frequency of extreme drought and flood in the NCP for each decade from 1740s to 1990s. It shows that extreme drought occurs more frequently in the 1770s–1780s, 1870s, 1900s–1930s and 1980s–1990s with at least two extreme events for each decade, and the two decades of the 1900s and the 1920s both had three events. Moreover, some of them occurred within 2–3 years consecutively, e.g., in the periods 1777–1778, 1876–1877, 1900–1902, and 1919–1920. These consecutive events usually caused severe impacts on agriculture and society. For example, the droughts in the period 1876–1877 led to evidently poor harvests with a reduction of about 45 % and 50 % in 1876 and 1877, respectively (Hao et al., 2010b). Even worse, this consecutive extreme drought further caused evidently delayed sowing and crop failure within several years after 1877, and led to the rice price to increase by 5–10 times than that in the normal year (Hao et al., 2010b). Such persistent and spatially large bad harvests and food scarcities not only caused more than one hundred million people to die because of famine but also triggered more than one hundred thousand refugees to emigrate from the NCP to eastern Inner Mongolia (Xiao et al., 2011b), which finally resulted in more than 13 million people to die from famine and plague (W. Li et al., 1994). However, there were no extreme droughts in the 1750s–1760s, 1820s–1830s, 1880s–1890s, 1950s and 1970s. Besides, the frequency of extreme drought showed a slightly increased trend (0.29 times per 100 year) from the 1740s to 1990s, but it was not statistically significant.
More frequent extreme floods occurred in the 1770s, 1790s, 1820s, 1880s,
1910s and 1950s–1960s with two or more occurrences per decade, but no
extreme flood occurred in the 1760s, 1780s, 1810s, 1840s, 1900s, 1920s, 1940s
and 1970s–1990s. Meanwhile, the most frequent extreme floods (4 events)
occurred in the 1790s and the 1880s, in which the consecutive
extreme flood years in the period 1797–1800 caused flowages from several rivers and
resulted in approximately
The occurrences of El Niño and La Niña events and large volcanic eruptions in the extreme drought/flood year and its previous year.
E represents El Niño, L represents La Niña, and the subscripts
represent their magnitudes, which were categorized into five grades: extreme
(E), very strong (VS), strong (S), moderate (M), and weak (W). The symbol
“–”
means that neither an El Niño/La Niña event nor a large volcanic
eruption occurred.
For extreme drought and flood events in total, most of them occurred in the 1770s, 1790s, 1870s–1880s, 1900s–1930s and 1960s, among which the 1790s witnessed the highest frequency of extreme drought and flood events. Such frequent extreme droughts and floods, together with climate cooling from the late 18th century, resulted in the regional socioeconomic system becoming more vulnerable around the turn of the 19th century in the NCP (Fang et al., 2013). Furthermore, more frequent extreme floods/droughts caused many negative impacts, e.g., vulnerable food security and significant increase in disaster victims, which led to the deterioration of refugee relief and more occurrence of peasant uprising (Xiao et al., 2011a). However, no extreme drought or flood event occurred in the 1760s or 1970s.
Table 1 shows the occurrences of ENSO (i.e., El Niño and La Niña
events) and large volcanic eruptions (i.e., VEI
The probabilities of extreme events occurrences with ENSO events and large volcanic eruptions.
The significance level of chi-test (
The chi-square test (
However, the chi-square test demonstrated that there is no significant connection for the occurrences between extreme flood and ENSO events (Table 2). In addition, the chi-square test also suggested that no significant link exists between the occurrences of extreme drought/flood events and large volcanic eruptions, although Shen et al. (2007) had argued that the large volcanic eruptions might trigger the exceptional drought events over eastern China.
This study investigated the decadal variation of extreme drought and flood over North China based on the 17-site seasonal precipitation reconstruction for 1736–2000, in which the extreme drought/flood events were defined as those with occurrence probability lower than 10 % in the reference period of 1951–2000, by considering the probability of drought/flood occurrence in each site and spatial coverage together. It is found that there were 29 extreme droughts and 28 extreme floods in North China during 1736–2000, in which precipitation decreased (increased) evidently in most sites for all seasons, especially in summer and autumn for most of them. In 1777–1778, 1876–1877, 1900–1902 and 1919–1920, the extreme droughts occurred sequentially, and in 1797–1800, 1882–1883, 1889–1890 and 1963–1964, the extreme floods appeared consequently. Compared to the previous studies on extreme droughts and floods derived from the yearly dryness/wetness grade data, this study found 9 extreme drought events and 18 extreme flood events that had not been reported previously.
Moreover, the results showed that there was an evidently decadal variation in
the occurrence of extreme drought/flood events from the 1740s to 1990s. In the
1770s–1780s, 1870s, 1900s–1930s and 1980s–1990s, the extreme drought
occurred at least 2 times in each decade, among which the most frequent
occurrences (3 times) were in the 1900s and the 1920s. While two or more
extreme floods occurred in the 1770s, 1790s, 1820s, 1880s, 1910s and
1950s–1960s, with 1790s and 1880s having the most frequent occurrences
(4 times). As the extreme drought and flood events in total, there were more
frequent in the 1770s, 1790s, 1870s–1880s, 1900s–1930s and the 1960s, and
the most frequent (5 events) decade was in the 1790s. In addition,
comparison of the occurrences of extreme drought/flood with the chronologies
of ENSO and large volcanic eruptions by the chi-square test (
The archive of Yu-Xue-Fen-Cun provided the quantitative records on rainfall and snowfall with high spatial and temporal resolutions for the seasonal precipitation reconstruction from 1736, which enabled us to investigate the variation of extreme drought and flood with seasonal features. Besides Yu-Xue-Fen-Cun, China also has other historical documents (e.g., local gazettes, official histories, weather diaries, etc.) with abundant and well-dated records on weather, anomalous climate, climate-related natural disasters, the impacts of weather and climate anomalies, as well as phenology, which have been used for the reconstruction of past climates extended to more than thousands of years at resolutions of annual to decadal timescales (Ge et al., 2016). Thus, most of them could be further applied to identify the regional extreme climate events at yearly resolution or prominent decadal climate anomalies before 1736, and to investigate the long-term pattern on the occurrences of regional extreme climate events associated with anomalous forcings in future works.
All reconstructed data for the
identification of extreme drought and flood events used in this study are
available in the Supplement. Chronology of El Niño and La Niña events
are available at
The supplement related to this article is available online at:
JZ and ZH designed the research and reconstructed the seasonal precipitation series; YY and XZ analysed the data; JZ and YY illustrated the plots. JZ, ZH and YY wrote the paper.
The authors declare that they have no conflict of interest.
This study was supported by the National Key R&D Program of China (2016YFA0600702), the National Natural Science Foundation of China (nos. 41430528, 41671201) and the Chinese Academy of Sciences (XDA19040101). Edited by: Marit-Solveig Seidenkrantz Reviewed by: two anonymous referees