Feng Shui and Imperial Examinations: A Case Study on the 1849 Severe Flood in Nanjing and Discussions on Flood Discharge

Social adaptations to natural hazards have been inuenced by various social and economic factors including traditional cultures such as Feng Shui that is known as Chinese geomancy. This study examined not only the progressive processes and spatial distribution of the 1849 severe ood in Nanjing city but also subsequent countermeasures based on historical documents, maps, and digital elevation model (DEM) data. As an adaptation to extreme oods, a project that connects Xuanwu Lake to the Yangtze River has been deeply discussed to relieve the ood risk. As the role of the traditional concept of Feng Shui in China was not neglectable, however, local ocials and elites of Nanjing city worried that the project may destroy the Feng Shui of the city, which may bring misfortune to local candidates in the Imperial Examinations, their future promotion, and the prosperity of their families. This indicates that, in the complicated traditional Chinese society, such traditional cultures may play an important role in determining social adaptations to climate change. However, these concepts may not lead to a consensus without specic institutional culture. Hence, in a complicated traditional society, the institutional culture was also fundamental to build social adaptations to climate change. This project has been eventually completed in 1931 as the concepts have kept dynamically being changed in a complicated society, which demonstrates that the relationship between the culture and the social adaptation to climate change is also evolving.

Interestingly, the adaptations in various societies have been selected corresponding to their characteristics mainly in the complexity and high heterogeneity of cultures, which has drawn great attention in academic communities. The unprecedented environmental pressures driven by the abnormal climate in the Late Holocene has prompted the Akkadian, Classic Maya, Mochica, Tiwanaku to a lower subsistence level by reducing social complexity, abandoning urban centers and reorganizing supply and production systems, i.e., adapting to a long-term drought with a lower level of living conditions (Peter B. deMenocal 2001). Traditional cultures in Africa have both positive and negative impacts on social adaptations to climate change. For instance, deforestation (such as felling trees and setting off a wild re) is a taboo in many areas of southern Africa, which is helpful for local people to adapt to climate change well (Chisadza B et al. 2015, Murphy C et al. 2016). On the contrary, relative policies affected by social cultures (e.g., the issues of gender, social classes, status, and taboos) on the social adaptation to climate change remain hard to be implemented in some areas in countries such as Burkina Faso, Kenya, Madagascar and Tanzania (Jonas Østergaard Nielsen et al. 2009, Rakotonarivo OS et al. 2017). In some areas in Cuba and Canada, a tradition that shares food with other people facilitates relieving natural disasters (Sygna L 2006). Most of these multi-disciplinary studies, combining with archaeology, cultural anthropology, and other disciplines, have displayed the unique role of culture as to how to cope with climate change in early human civilization or simple civilized societies. In addition, these studies lead to a big step forward to understanding the relationship between culture and social adaptation.
The Chinese culture has evolved continuously with a long development history over the last nearly 6,000 years. Especially, China has formed a cultural system characterized by complex and rich content from a wide territory and a huge population (20% of the world's population) (Liang SM 2005). The Chinese culture may be an important cultural system in the world as it directly affects the philosophy for not only people in China but also many overseas Chinese and people in the world at different degrees.
There are systematic and abundant historical documents and materials in China, which provides valuable information on climatic events during different historical periods, their impacts, and social adaptations to cope with extreme events. This information may give an opportunity to investigate the impacts of historic extreme climate events and corresponding adaptation mechanisms. With these historical documents and materials, many scholars and researchers have studied the impacts of the historic climate change with regard to wars, politics, population, agriculture, economy, and society (Zhang D et al. 2004, Fang XQ et al. 2014, Fang XQ et al. 2015, Pei Q 2017, Fang XQi et al. 2019. However, there is still room to further investigate how a traditional culture in a complex cultural system might affect social adaptations relevant to these historic extreme events to enhance understanding of how the traditional Chinese society adapted to climate change and how a speci c culture in a complex cultural system in uenced on social adaptations to climate change. Nanjing City is located between 32° 00" N to 32° 05" N and 118° 45" E to 118° 50" E, which includes the Yangtze River in the west and mountainous borders in the east. It has a northern subtropical humid climate with distinct seasons and abundant rainfall. As a prominent city with more than 2,400-year history, Nanjing City is an important ancient capital in Chinese history. In the Qing dynasty (1644-1912), Nanjing was a station where the Liang Jiang Governor lived and worked, who had jurisdiction over the present Jiangsu, Jiangxi and Anhui provinces and Shanghai city in the lower reaches of the Yangtze River. Besides, Nanjing was the center of politics and military and one of the largest cities that has a population of 700,000 (Cao SJ 2001;Jiang WT 2013). Therefore, Nanjing had a crucial role in nance, taxation, food, goods, and materials for the Qing dynasty. In 1842, the Treaty of Nanjing was signed in the city of Nanjing at a part of the Yangtze River that runs through Nanjing. The Jiangnan Examination Hall, the largest and most in uential hall for the Imperial Examinations in Chinese history, was also located in Nanjing.
Nanjing city located in the Jiangnan Hills area to the south of the Yangtze River has unique topographical and physiographical characteristics that it has a large high-elevation area in the west of the city, many ponds and rivers in the east and south of the city, and low-lying areas prone to be affected by backwater effects. Xuanwu Lake is located in the north of Nanjing city, which is downstream of the mountain headwater area in the northwest of the city and ows into the Qinhuai River through the city. The water discharged from Xuanwu Lake may contribute to the inundation in Nanjing. In 1849, the plum rain season occurred earlier and lasted longer than normal years, which caused a severe ood over the middle and lower reaches in the Yangtze River (Yang YD et al. 2008, Yan CQ et al. 2011.A map of study area and ooding grade in 1849 was shown in Fig. 1 using QGIS techniques,and the ooding grade was acquired using rank method according to data from historical records in China (Yang YD et al. 2014).The ood in uenced 237 of 432 county-level places in 6 provinces in the middle and lower reaches of the Yangtze River, Nanjing city and surrounding areas were extremely serious inundated (Yang YD et al. 2008). An increase in the water table of Xuanwu Lake caused by abnormal plum rains, aggravated the inundation in the city, provoking the discussion on a project that connects Xuanwu Lake to the Yangtze River. This is a representative case that shows the role of a speci c traditional concept incorporated into the processes of social adaptations. This study reconstructed the 1849 ood event with methods in historical geography and analyzed the role of Feng Shui, a traditional Chinese culture, in a social adaptation derived from the discussions on the project. This study provides a mechanism of how traditional culture in China affects the social adaptation to climate change and enhances understanding of the complex processes and mechanisms that re ect a complicated culture in adapting to climate change.
2 Materials And Methods

Materials
Detailed historical documents and materials are fundamental information for this study. From local chronicles, collected works, factual records, compilations, the 1849 severe ood-related information was extracted such as the inundated areas, progressive processes, disaster relief, and water system in Nanjing, historical data for Xuanwu Lake, and historical documents related to the discussions of the project, connecting Xuanwu Lake to the Yangtze River, held in Nanjing from the Qing dynasty to the Republic of China. In addition to Digital elevation model (DEM) data, the maps of Nanjing at different scales in 1856, 1909, 1935 and 1950 were used to retrieve the historical geographic information of the city. All materials and corresponding information retrieved in this study are shown in Table 1.

Methods
This study employed a historical geography method with support from historical documents and materials, maps, and DEM. QGIS was used to re-render the distribution map of the 1849 ood in Nanjing city and to examine progressive processes, spatial distribution, and severity. In addition, historical analysis was applied to evaluate the in uence of the concept of Feng Shui on society and a relevant mechanism according to the historical documents and materials listed in Table 1. 3 Results

Impact of the severe ood on Nanjing city
In 1849, the plum rain season in the middle and lower reaches of the Yangtze River has lasted for 62 days, resulting in three times of mean precipitation during the period, which caused severe inundation in Nanjing city (Yang YD et al. 2008). Nanjing city was in severe inundation for six months from late May to late November. While the amount of rain in Nanjing was light for the rst twenty days from late May to early June, it abruptly turned heavy on May 19, which has been recorded as an incunabular inundation in Nanjing city. The heavy rain lasted from early June to mid-July, resulting in more severe inundation in Nanjing city. Although the rain was abated again in late July and dry-days lasted for 20 days from late July to early August, the inundation was not relieved and even worsened by upstream ows and backwater effects from the downstream. In late August, the ood nally receded in high areas within the city. However, ooding damages were still progressive and serious in low-lying areas until late November.
This study presented a DEM at a vertical resolution of 1m for Nanjing city using QGIS techniques. A ooding map of the 1849 ood in Nanjing city was shown in Fig. 2, referring to historical maps and records of the damaged areas in historical documents. Figure 2 shows that the inundated area in the city reached nearly 19 km² across low-lying areas of the middle, east and west of the city, which accounts for 44% of the total area of the city. Many houses for public o cials, soldiers and citizens were all inundated, collapsed and damaged in Nanjing city, which caused many social problems such as homeless and governmental business suspension. In 1849, many people suffered a survival crisis without residence and food for half a year in Nanjing city.

Waterlogging in Nanjing city and in uence from Xuanwu Lake
As the outlet of drainage in the city is at the Qinhuai River, preserving the water level of the Qinhuai River is critical to avoid ood damages. The mean water level of the Qinhuai River is 6.57 m, which is an elevation lower than residential areas in Nanjing city and higher than the low water level of the Yangtze River. However, during the ood year, the water level of the Qinhuai River reached 9.90 m at the Wuding Floodgate (Nanjing Municipal Compilation Commission of Local Chronicles 1994), which was extremely higher than the elevation of residential areas in the city. Hence, the city has built oodgates since the Ming dynasty to control the waterways of the Qinhuai River through the city. However, the peak ow level in the Yangtze River was much higher than the water level of the Qinhuai River, causing a severe backwater effect that supplementarily increases the water level in upstream areas. For instance, the backwater occurred in the Qinhuai River when a peak ow level in the Yangtze River reached 10.22 m in 1954 (Nanjing Municipal Compilation Commission of Local Chronicles 1994). The 1849 ood in the Yangtze River also caused the backwater effect on the Qinhuai River. Unfortunately, the oodgates were damaged during the ood period, and subsequently, the ood damage in the city was aggravated more.
The 1849 ood in Nanjing was mainly caused by the heavy rainfall in the entire Yangtze River basin. The 1954 severe ood is the severest one in history since data recorded although ooding events rarely occurred historically in the city. Considering the precipitation during the plum rain season in 1954 was 623.4 mm for 48 days and increased up to 892.6 mm from May to July (Nanjing Municipal Compilation Commission of Local Chronicles 1994), the precipitation from May to July in 1849 should not be less compared with that in 1954.
The oodgates located in the Qinhuai River have usually been closed during the ood season to protect the city from ood damages. However, the water in the city is not drained away when the oodgates are closed. Therefore, the precipitation mainly causes waterlogging in the city. Nanjing city has a drainage area of 43 km² that includes a mountainous area in the west of the city. Rainfall-induced surface runoff ows to the ponds, waterways, and other low-lying areas in the city, which may cause oods in the lowlying residential areas. Assuming that the precipitation in the city in 1849 was the same as that from May to July in 1954, this study evaluated the precipitation of 3.83×10 7 m³ in the city and calculated the runoff by a simple method with a runoff coe cient. Due to the lack of the runoff coe cient of Nanjing in the ood season, this study employed the runoff coe cient (0.71) of a nearby city, Changzhou (Yan YQ et al. 2017). As a result, this study generated a runoff of 2.72×10 7 m³, causing serious waterlogging in the lowlying areas of the city.

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The waterlogging in Nanjing city was aggravated by Xuanwu Lake that supplies domestic water for residents in the city and has a water level elevation of 11 meters, a water surface area of 3.6 km² and a basin area of 26 km². While the water level elevation was then higher than the elevation of most residential areas in the city, the water level elevation of Xuanwu Lake nowadays was lower than the elevation of most areas in the city. In addition, a landscape park has been developed around it. Xuanwu Lake, the pondage less than 3,000,000 m³, had never been dredged throughout the Qing dynasty (Nanjing Municipal Compilation Commission of Local Chronicles 1994) and it had lost the ood control function.
As rainstorm-induced oods in the basin may ow into Xuanwu Lake and the city, Xuanwu Lake was the main water system that ows into the city except for the Qinhuai River. Therefore, Xuanwu Lake would become the main source of the external water that causes ooding in the city when the Qinhuai River is closed by the oodgates.
Employing the same precipitation and runoff coe cient, the surface runoff of 1.65×10 7 m³ from the Xuanwu Lake basin from May to July in 1849 was calculated. In addition, this study evaluated the volume of waterlogging, 4.37×10 7 m³, and found that the water from Xuanwu Lake accounted for 37.68%.
Furthermore, the backwater effect of Xuanwu Lake was superimposed on the internal waters in the city, causing more serious ooding damages. Hence, controlling the water of Xuanwu Lake and discharging directly into the Yangtze River during the ood season was raised as an alternative to relieve the severe waterlogging in Nanjing city.

Countermeasures for the severe ood
The Qing government adopted a lot of countermeasures, mainly focusing on not only providing food and shelter but also bringing the functions of cities back to normal.  Company 2008). Thirdly, the work relief policy was promoted. Besides, the farmland was protected with the 'Gui Tian method' by building rm walls and should drain the water in the farmland away by waterwheels. Lastly, the Qing government supplied food from Fujian and other provinces to Nanjing. All rice loading boats that sail to disasteraffected areas such as Nanjing were temporarily exempted from the frequent tariff and were allowed to load pisolites to encourage transporting foods to Nanjing (Zhonghua Book Company 2008). Generally, the Qing government played a leading role in relieving the ood, which was effective to a certain extent. At a non-government level, all social classes also actively responded to the severe ood to mitigate the impacts. While houses and crops were ooded, victims ed to higher places. After the ood subsided, they tried to drain the water away to reduce ood damages and grew crops and vegetables (Zhonghua Book Company 2008). According to historical documents, many elites and rich families responded to the appeal of the government for disaster relief as well as donating money or food to Nanjing city for the 1849 severe ood.

The discussions of the project of connecting Xuanwu Lake to the Yangtze River
Due to the severe ood in 1849, Yang Wending (?-1856), the Financial Commissioner of Jiangning, realized that a channel needs to be built in the northwest of Nanjing city to relieve the ood, which directly drains the water from Xuanwu Lake to the Yangtze River. Therefore, Yang Wending assigned special personnel to conduct the measurement, piling and other works outside the city and to prepare for the construction in the early spring (Gan X 2007).
While the plan that connects Xuanwu Lake to the Yangze River drew the attention of all social classes in Nanjing, civilians and local elites were all in panic." , "( More than 100 students assembled and marched to the government o ces to submit their petition against the project)(Gan X 2007). Subsequently, some elites and o cials opposed the plan, such as Mei Zengliang, Chen Zuolin, Gan Xi, Gan Xun and Wei Yuan. Mei Zengliang (1786-1856) submitted his petition of " " (On the Flood in Jiangning to Governor Lu) to Lu Jianying, pointing out that the proposal of the project that connects Xuanwu Lake to the Yangtze River was absurd because building a channel and draining the water from the lake would " " (cut the huge Dragon Vein) (Dragon Vein, terminology of Feng Shui, a geographic form with unexceptionable Feng Shui) that gathers spirit Qi in Feng Shui and consequently brings good fortune to people living nearby Nanjing city (Xia RH 2013). Instead, he advocated dredging Xuanwu Lake to drain the water away by waterwheels under oods. Chen Zuolin (1837-1920), then merely 13 years old, studied the , , (Veritable Records of Jiankang, Illustrations of Danyang and Records of Jiankang in the Jingding Reign) and wrote " "(On the Disapproval of the Project of Connecting the Houhu Lake to the Yangze River). He presented the disadvantages of the project and thought that Xuanwu Lake was the" " (amniotic uid' for Nanjing. Once it leaked out, then it would converge in the city, bringing misfortune to everyone in the city, including o cials and civilians)(Xia RH 2013). He also proposed an alternative that dredges the lake to enhance the embankments. Gan Xi (1798-1853) believed that Xuanwu Lake connected to the Qinhuai River ow into the Yangtze River through the Xishuiguan Floodgate, which is the " "(amniotic uid' to nourish the Dragon Vein in the Zhongshan Mountain, and consequently it should not be drained away) (Gan X 2007). Wei Yuan (1794-1857) is a famous thinker in China who was called" "(the rst person in China who sees the world outside China as he introduced western thoughts and cultures to China for the rst time) (Chen QTi et al. 2011). Hearing about the project, even he thought that it was absurd. He then visited Lu Jianying and tried to persuade him that Xuanwu Lake should not be connected to the Yangtze River (Gan X 2007), which was spread to Beijing after that. As a result, those o cials who were from Nanjing were horri ed to be stepped down dishonorably. Fan Xiaoyun, the Investigating Censor, also prepared to impeach the o cials who presided over the project.
Lu Jianying (1792-1853) led some people to survey the Dragon Vein of Nanjing in early March of 1850. They found that the position where Xuanwu Lake was located was" , " (the place where the Central Dragon Vein entered the city, which was of great importance to the whole city. The bene ts of the project were hard to quantitatively evaluate. However, it was prominent that the consequences of the project were surely serious. We had barely done something for this place, how could we ruin the future) (Gan X 2007). The project was nally abolished in 1850 with the hindrance of the elite and civilians of the city. After that, the discussions of the project of connecting Xuanwu Lake to the Yangtze River had not been held even once from the Qing dynasty to the Republic of China. They were also conducted in 1832, 1841, 1851 and 1931 (Table 2). During these discussions, those who supported the project such as Cheng Shixuan (1790-1842), Lu Jianying (1792-1853) and Yang Wending (?-1856) were all working in Nanjing but were not born in the place. The opponents of this project, consisting of mainly native civilians and elites of Nanjing, thought that the project may damage the Dragon Vein and then the Feng Shui of Nanjing, consequently bringing misfortune to them in terms of personal safety, nances and performance in the Imperial Examinations.

Discussion
"Feng Shui", another name of "Geomancy", focuses on the selection and construction of the living environment (Fan JZ 1994). "Feng Shui" was recorded in the Book of Burial of Guo Pu (276-324) in Jin dynasty for the rst time: " , …… : "(The buried dead should be embraced by the vital Qi that disperses with wind and gathers with water. Hence, ancient people circulated it and at the same time gathered it to prevent it from dispersing. This is called "Feng Shui".) (Guo P 1986). However, the concept of Feng Shui in China could be found in the residence selection of ancient people in the Neolithic Age and in oracle bone inscriptions during the Shang dynasty such as information relevant to the divination for selection of places, since much earlier than the Jin dynasty. A systematic Feng Shui theory has been formed in the Han Dynasty 202B.C.-220A.D.) and improved in the Wei, Jin, Southern and Northern dynasties (220-589A.D.) In the late Tang dynasty, the Feng Shui theory has been gradually spread to places such as the Korean Peninsula, Japan and Southeast Asia (Fan JZ 1994;Hong-key Yoon 1989).
Feng Shui has been also widely used not only in daily life but also in the construction of residences, graves, and cities during the historical period. Furthermore, Feng Shui has in uenced many aspects of society nowadays. The divination based on Feng Shui was conducted for orientation selection and construction of residences and graves, in an attempt to bless people living inside of the construction and their offspring (Hong-key Yoon 1989). The location, planning, design and construction of public infrastructures (e.g., public housing, gardens, temples, roads, bridges, etc) have been determined based on Feng Shui (Wai-Yee Li 2012). Feng Shui is also indispensable during the birth of cities and villages. Those capital cities of each dynasty in history, e.g., Xi'an, Beijing, Luoyang, Kaifeng and Nanjing, were all selected based on Feng Shui, which was conducive to the continuation of the dynasties (Chen AP 2003).
Public buildings were also in uenced by Feng Shui. Production activities such as mining, placing waterpowered pestles, sinking wells and planting trees were also affected to some extent by Feng Shui (Chen Feng Shui contributes to developing a harmonious and mutually supportive relationship between humans and nature (e.g., surrounding environment, climate, meteorology, etc.), subsequently, bringing good fortune to people and their offspring (Dan W 1994). As Feng Shui is characterized as the pro t-seeking and harm-avoiding features that are extremely attractive to most people, including the emperors and civilians.
In traditional Chinese society, Feng Shui has been often used to improve the performance in the Imperial Examinations that is a unique and important system not only to select o cials but also to maintain the traditional Chinese society (He ZL 2000). As the Imperial Examination provided a fair competition to be In the late Qing dynasty (1644-1912), Nanjing city was severely ooded many times, creating profound impacts on o cials, elites, and civilians in the city, subsequently leading to many discussions on the project that connects Xuanwu Lake to the Yangtze River. The failure of the project to be put into practice was originated from the fear of o cials, elites and civilians with regard to disrupting Feng Shui in Nanjing at that time as well as a subtle relationship between local o cials, elites and civilians.
The elite, local intellectuals, had a wide variety of political, economic, and legal privileges that were generally recognized by the government and the public. They closely engaged in local administrative work and had a strong in uence on deciding local policies (T'ung-tsu Ch'u 2011). Besides, ordinary people were eager to raise their social status through the Imperial Examinations, i.e., having the status of the elite through it (Zhang ZL 1991). Local people were quali ed to be o cials and then they could maintain their social status at a high level in the government by passing Imperial Examinations. Therefore, the project that connects Xuanwu Lake to the Yangtze River was intensely opposed by the elite and ordinary people in Nanjing city. The elite in Nanjing city believed that building a channel may destroy the Feng Shui of the city, subsequently causing misfortune on the Imperial Examinations in the place. In other words, they are concerned that the number of those local students who pass the Imperial Examinations may be greatly lessened, which means that the number of o cials from the city may be decreased and consequently weakening the power of local elites. To maintain the status they had achieved, the families of the elite were necessary to ensure that their offspring could pass the Imperial Examinations continuously. That is, the families of the elite attached great importance to the family inheritance in traditional China. Moreover, the elite did not want to face this situation even if it could only possibly happen. As students and ordinary people were also eager to raise the status of themselves and their families through the Imperial Examinations, they were afraid that the possibility of passing the Imperial Examinations would be lessened by the alteration of Feng Shui. Therefore, the elite smoothly led local students and civilians into preventing the project from being carried out.
O cials from other places were also persuaded by the local elites. On the one hand, the development of Nanjing city might be affected by concerns that Feng Shui was destroyed by the project. The local development was one of the standards for o cials to assess their performance, and consequently, it was highly related to their promotion. Therefore, the destruction of Feng Shui would likely affect their careers.
On the contrary, o cials from other places such as Cheng Shixuan (1790-1842), Lu Jianying (1792-1853), and Yang Wending (?-1856) were usually tied with local affairs and thus might have little knowledge about the place. In contrast, however, local elites, especially those who had been o cials, knew the place in detail. Moreover, most of them had experience in administration and could advise on or even participate in public works, local defense and other complex affairs (T'ung-tsu Ch'u 2011). Therefore, the local elites were essential for successfully implementing the order of o cials in Nanjing with governance. Furthermore, if o cials carried out their plans without the consent of local elites, the local elites might provoke those o cials in the capital behind and put their careers at risk. Therefore, the disapproval from relevant o cials in the project was not only a concession to the local elites but also the result of considering their interests.
In earlier, it was found that the concept of "Feng Shui", as a cultural factor, in uences social behaviors through social choices to avoid misfortune. In this aspect, there is no difference between the Feng Shui in China and the cultural taboos of traditional African cultures. However, it can also be concluded that the institutional culture, namely the Imperial Examinations system in this study, is the main factor behind the role of Feng Shui in the project that connects Xuanwu Lake to the Yangtze River. The Imperial Examinations were then very important to improve and maintain social status. Hence, any changes that may induce a decrease in the number of local students who pass the Imperial Examinations may be strongly opposed by the local elites and civilians. In such a complicated traditional society with developed institutional systems, therefore, corresponding systems that re ect a cultural factor are needed for social adaptations to be timely implemented.
In addition, there were many cultural factors in complicated traditional China. Most people were superstitious about Feng Shui while it was still regarded as a folk culture that is independent of the orthodox Confucianism culture and is opposed by Confucians(Li XF, Wen XX 2007).As the so-called veri cation of the Feng Shui theory was then mostly based on stories and superstition, it was no accident that the project of connecting Xuanwu Lake to the Yangtze River was kept discussing during the Qing dynasty when the traditional culture was dominating. However, the Nanjing National Government put the plan into practice in 1931, only 80 years later since it had been proposed, indicating that a concept is not unbreakable without the change of corresponding social systems.
In 1931, a severe ood, once-in-a-century, stroke the middle and lower reaches of the Yangtze River.
Nanjing city also suffered from serious ood damages again. The plan that connects Xuanwu Lake to the Yangtze River was raised again and implemented later. There are many factors that attribute to the success of the project after more than 80 years since it had been proposed. Firstly, the Imperial Examinations were revoked. In the meantime, the feudal monarchy has been destroyed in China after the Revolution of 1911. Under the New Culture Movement from 1910 to 1920 that science and democracy were strongly promoted, an advanced social education model was increasingly spread with "popular education" and "civilian education" as the main body. As a result, the society embraced a new phase that was different from that of the last century (O ce of Nanjing Municipal Committee of the Compilation of Local Chronicles 2011). Secondly, the project that connects Xuanwu Lake to the Yangze River was supported by the Nanjing National Government. In 1928, Nanjing was selected as the capital of the Nanjing National Government. Moreover, many senior o cials have been adapted to western cultures from studying abroad. For example, Liu Jiwen, Wei Daoming and Ma Chaojun who served as the mayor of Nanjing, had studied in Europe, the United States and Japan, respectively. As they also regarded science as important, the project was greatly supported by the central government and the municipal government. Thirdly, the project was supported to improve waterways in Nanjing as part of the Capital Plan that was designed to transform Nanjing into a modern city (O ce of Nanjing Municipal Committee of the Compilation of Local Chronicles 2011). Fourthly, an advance in construction technologies contributed signi cantly with regard to accurately evaluating the consequences of the project by precise engineering surveying and planning to ensure that it could discharge water during the ood season and maintain its normal water level during the rest of the time (Nanjing Municipal Government 1932).

Conclusion
In 1849, the severe ood in the Yangtze River basin has caused serious impacts on socio-economic components in Nanjing such as human lives, agricultural products, urban systems and infrastructures.
The Qing government has implemented postactive policies to mitigate the impacts of the ood by granting relief funds, exempting taxes and tariffs for some places and boats, adopting work relief, enhancing a food supply channel and appealing for donations. Non-governmental forces also took part in mitigating ood damages actively. The severe ood prompted a series of discussions on the project that connects Xuanwu Lake to the Yangtze River, in an attempt to fundamentally reduce oods in Nanjing. However, the local elites opposed and stopped the project based on a concept of Feng Shui, pro t-seeking and harm-avoiding features, that has a wide in uence on all social classes. In other words, they worried that the project may change the Feng Shui, consequently bringing misfortune for local students in the Imperial Examinations and the development of the city and their families.
In complicated traditional China, traditional concepts were also important to social adaptations to climate change. However, the concept of Feng Shui is not the same as that of the cultural factors of indigenous Africans such as beliefs, taboos, ethnic groups, and gender. As the former needs to be bound with speci c institutional factors, the deep in uence of developed institutions on people may affect a decision-making process. In this sense, the institutional culture may be fundamental to determine social adaptations to climate change in a complicated society. However, the role of concepts is also of great importance.
From the 1849 severe ood, it is found that culture is dynamic in a complicated social background and is continuously changed along with the in uence of institutional changes, educational development, the guidance of the media guidance, etc. Besides, culture is always evolving while helping or restraining social adaptations to climate change. It is indispensable to build social adaptations by better understanding a complicated cultural system and its possible roles in determining social adaptations to climate change as well as the in uencing pathways and mechanisms.