by Ling Zhang
The higher the river body rises, the more likely it will overflow, and the more powerful its flooding will be. Beginning in the seventh century BCE, kingdoms along the river's lower reaches entered a “dyking race,” meaning that they competed with each other to construct lengthy high dykes to keep out both floods and silt. Those who did not build dykes would become victims not only of the river's torrents but also of their neighbors’ hydraulic infrastructure. The dyking technique, however, induced negative consequences and led to more flooding disasters. The dykes straightjacketed the river course and fixed the water and silt within a limited space. Such spatial confinement accelerated the accumulation of sediments in the riverbed and thereby the latter's elevation. As a result, the river's hydrological force pushed even harder against the dykes, and the river's water was more likely to burst through them.
The one and a half millennia prior to 1048 saw an endless wrestling between human efforts to build more dykes and the river's desire to run free. When the river succeeded in overcoming the dykes, the massive force of water would pour out onto the surrounding low ground and wreak havoc over a vast area. In 132 BCE, for instance, a terrible bank rupture at the site of Huzi 瓠子 led to the inundation of all of southern Hebei and northern Henan. It took Emperor Wudi of the Western Han Dynasty twenty years to come to the conclusion that the bank rupture had to be fixed at any cost. He visited the bank rupture personally and presented extravagant sacrifices to Heaven and Earth. He even composed a prose poem to express his despair over the calamity, as well as to document the tremendous human efforts under his leadership to fix the rupture. His officials, regardless of status and position, carried wood and stones to the riverside to perform flood-control work. Dealing with the aftermath of the floods took the state over twenty years; as one of its many costs, the bamboos in the state-owned forests in Henan were completely felled for use as construction material.22
The river's destruction seems to have become even more severe at the turn of the first millennium. Archaeological works led by T. R. Kidder have shown a remarkable earth stratum 10 meters under the present land surface, which was produced by floods and resulting sediments in that period.23 Continuous flooding certainly contributed to the political upheaval and social instability, so it is reasonable for us to consider that river-related environmental disasters must have played a significant role in the dwindling of the Western Han Dynasty and the tragic failure of Wang Mang 王莽's short-lived Xin 新 Dynasty. The environmental conditions of the river carried immense political and socio-economic implications.
Flooding began to reduce in the first century, partly because of the improvement in environmental conditions after human activities on the Loess Plateau decreased, and partly because of innovations in hydraulic knowledge and technology. Previous historical writings have generally attribute the decrease of floods to the hydraulic works conducted by Wang Jing 王景 in the first century. Wang witnessed the overwhelming power of the Yellow River and learnt the technical limitation of fragmented dykes. To tame the violent river, he believed it necessary to observe the natural conditions of geography, to choose and design a suitable route for the river, and then to install a holistic dyke system that contained the entire river rather than only sections of it. Not much is left of Wang's hydraulic legacy today, but historical literature suggests that he developed a brand new course for the river, flanking it on both sides with strong dykes that stretched over 500–600 kilometers.24
Illustration 4. The Yellow River's Lower Reaches before 1048
Wang Jing's river course remained functional for the next nine centuries, and the river's lower reaches appeared peaceful. Very few flooding events were reported in the North China Plain. We cannot judge to what extent the tranquil state of the river is attributable to Wang's hydraulic work, because there are not many extant historical sources that offer evidence. Whatever brought about a stable, gentle river, we know for certain that the first century marked a significant change in the river's relationship with the land of Hebei. Wang Jing's eastward-flowing river course divided the land of Hebei from that of Henan. The river's long-lasting geographical stability even granted these two regions their identities: Hebei eventually acquired its literal name as “the land north of the river,” in contrast to Henan, “the land south of the river.” From then until the tenth century, the river made very little trouble for Hebei and its people; it certainly never invaded Hebei's territory before the eleventh century.
Sadly, the tranquility that people on the North China Plain had enjoyed for nearly one thousand years gradually came to an end, as the environmental conditions in the upstream area continued to deteriorate and, very likely, Wang Jing's dykes slowly broke down. The accumulation of silt made certain parts of the river increasingly vulnerable to flooding. In the tenth century, bank ruptures and floods occurred in twenty-four individual years. Most of them happened within a small area in the Huazhou 滑州 and Chanzhou 澶州 prefectures, where the river's channel zigzagged, the earth supporting the dykes was loose and fragile, and the currents tended to be turbulent. Through the tenth and eleventh centuries, this dangerous section of the river saw the most major flooding and course shifts.
Meanwhile, from the late tenth century on, sediments began to deposit at the river's estuary and block river water from entering the sea. Dizhou 棣州 prefecture, for instance, was close to the ocean and saw the river flowing through the southern half of its domain. In the 980s, this district carried 56,178 registered households, roughly 280,890 people.25 Here, the riverbed of the Yellow River had risen nearly ten meters above its surrounding ground. The dykes could no longer be built higher, and the increasing pressure of water occasionally crashed through them. Between 1007 and 1014, floods struck the capital city of the prefecture every year. In 1014, a flood nearly submerged the entire city, forcing local officials to petition to the imperial court to abandon the city and remove its residents. Soon after people evacuated, the city of Dizhou was completely submerged by a second flood.26
This eastward movement of flooding problems toward the river mouth did not alleviate pressure on the river's upstream sections. Rather, by the beginning of the eleventh century, the entire 700 kilometers of the river's lower reaches had become highly problematic; its various sections were troubled by different kinds of hydrological mechanisms. The blockage of the river mouth must have jeopardized the river's normal flow and caused both water and silt to surge backward. There is no historical source to demonstrate this phenomenon, but with basic hydrological knowledge, one may imagine that the counter-directional flow from the coastal area surged westward to clash with the river's eastward-flowing mainstream. Wherever these two hydrological forces met saw great damage. In the early eleventh century, these clashes happened again and again in the Huazhou-Chanzhou area. In the years 1015, 1019–1021, 1034, and eventually in 1048, the river provoked its most serious bank ruptures and floods precisely in this area.
This brief survey of the river's history charts a gradual end to the thousand years of tranquility, both in terms of the river's conditions and the North China Plain's experiences of environmental stability and disturbance. The catastrophic events that began to occur in the eleventh century were in fact a culmination of a growing trend of river disasters. Situating the momentary environmental event in 1048 in a complex temporal-spatial context helps us see clearly how the currents of history had been preparing its actors – the river, the land of north China and the people residing there, and governmental and political figures – for the dramatic outbreak of a catastrophe like the 1048 event. Hence, the environmental drama presented in this book did not come about as some random event; rather, it was the result of a series of causal relations complicated by both natural factors and human activities.
1.2 The Autonomous Plain
Hebei as a Geographical Entity
Before the Yellow River's penetration in 1048, Hebei was a land “north of the Yellow River.” For nearly a millennium, not only did Hebei experie
nce limited environmental impact from the river, it utilized the river's broad, heavy body as a natural barrier to shield itself from the rest of China. The river endowed Hebei with a geographical boundary as well as a sense of separation and independence – both Hebei and the rest of China saw Hebei as its own entity, distinct from other regions.
Geographically, the plain resides at the northeastern corner of traditional Chinese territory. In the east, it abuts on the Gulf of Bohai, where the sea cuts off its connection with any other landmass, such as the peninsulas of Shandong, Liaoning 遼寧, and Korea. In the west, the plain leans against the Taihang Mountains 太行山, which stretch north–south over four hundred kilometers and stand over a thousand meters in altitude, high enough to block Hebei from the highland of Shanxi 山西. To the north, Hebei's geographical division from its neighbor is not as sharp as in the other three directions. The century-long battles between the Han Chinese and the Khitan 契丹 took place here, resulting in the display of troops and fortresses on both sides of the Juma 拒馬 River. The political and military situation had long established the Juma River as the de facto northern boundary of Song-occupied Hebei. In 1005, the Song and Khitan's Liao 遼 (907–1125) states issued a peace treaty and officially declared the Juma River a border between the two states. Hence, the medium-size Juma River served as both the political and the geographical northern edge of the plain.
Illustration 5. Hebei in the Tenth Century
Given this geographical contour, the “Hebei” plain at question in this book refers roughly to the land called the “Jizhou 冀州” region during the Han and Three Kingdoms 三國 periods (the second century BCE through the third century CE), the southern half of the “Hebei dao” during the Tang period (the early seventh through early tenth century), and the southern half of the “Zhili 直隸” region in the Ming 明 and Qing 清 periods (the early fifteenth through the early twentieth century). This region, thus, is also different from modern Hebei Province whose territory includes a vast area north of the Juma River, where modern Beijing 北京 is located. Hebei in the tenth to twelfth centuries refers to the southern half of modern Hebei Province, the region administered under the name of “Hebei lu” by the Northern Song Dynasty. The land to its north, the northern half of modern Hebei that includes the city of Beijing today, was under the control of the Liao Dynasty as the Liao's “Nanjing 南京” district during the tenth to twelfth centuries. Its land and people underwent a drastic political, socio-economic, and cultural transformation due to nomadic influences. Readers should note that the present book does not study that northern land; the Hebei Plain here is strictly defined as the land south of the Juma River.27
Bracketed by these rivers, mountains, and sea, Hebei distinguishes itself from its neighboring areas. It stands out as a material entity with a clearly defined geophysical enclosure. This book foregrounds a geographical definition of Hebei, acknowledging it foremost as a plain in the geographical sense, before regarding it as a socio-economic and cultural region, or as a political, administrative unit of the Song empire. These three definitions of the land are correlated, and they often overlap each other in terms of their spatial coverage. In this book, the term Hebei often refers to the three meanings in an interchangeable manner, with an understanding that the geophysical existence of the land lays the foundation for its other significances. In places where more clarity is needed, I shall explain in exactly which sense the term is being used.
By emphasizing Hebei as an enclosed geographical entity that enjoys rather uniform materiality, I highlight Hebei's image as an environmental entity equal to but distinct from other environmental entities, like the Yellow River and the imperial state. I honor Hebei's roles as a participant and actor in history, which performed and interacted with other historical actors in the complex process of making north China's environmental history. Hebei did not participate in the historical process nominally, as an abstract political unit bearing an administrative title, nor did it participate merely as a conceptual substitute for anthropocentric subjects like people, their society, and their collective culture. As a geophysical entity, Hebei not only served as a material site where various environmental changes and exchanges as well as political and economic activities took place, it also acted as both a recipient and an object of these changes and activities, which modified the land's physicality in various ways. Most importantly, the land responded to the movement of the Yellow River and the interventions of human activities by setting limitations or provoking reactions. It defined the ways in which the river behaved within its territory; it shaped and reshaped the livelihood of the people who were affected by every change to the land's materiality. The land itself kept changing and took part in the endless making and unfolding of the historical drama. By playing participatory roles in the environmental process, and by way of its constant reciprocation with other entities, the plain of Hebei made itself a prominent historical actor.
This geographical entity distinguishes itself through its internal geophysical singularity. First, although it covers a vast area of roughly 120,000 square kilometers (back in the Northern Song period28), nearly as large as modern-day England, the land sees little variation in elevation. Being a typical plain, Hebei lacks fluctuation of its surface; it spreads out smoothly, seeing no significant obstacle, like mountains, to divide the land into distinctively different sections.
Second, nearly the entire area is uniformly low-lying. Born as a tectonic sink millions of years ago, it has continued to sink, as the mountainous terrains around it continue their uplift. Except for a narrow strip along the foot of the Taihang Mountains where the terrain is relatively high, the plain stands only 50–20 meters above sea level on average, much lower than other areas in north China. From western Hebei to the eastern coast, a distance of 400 kilometers, the land's altitude gradually drops from 100 to 2 meters. The change in gradient is so minor that across Hebei one may not observe much topographic difference.
Third, Hebei is climactically varied: the eastern coastal area receives more oceanic influence; the western mountainous area traps higher humidity and thereby enjoys more rainfall in the rainy season; while the central plain suffers higher aridity and lacks any shield against summer heat, strong winds, or cold fronts. Nevertheless, in general, the plain shares a relatively uniform continental temperate climate. Located between latitudes 35° and 39° north, this area is dominated by interplays between the southward movement of cold, dry air masses from Siberia–Mongolia and the northwestward movement of warm, moist air masses from the Pacific. When the northern forces rule, they produce a cool, dry Hebei during a large portion of the year. Spring and summer are usually short, but the temperature can go up to 35°C in most places.
Throughout Hebei, the temperature drops under the freezing point in winter, now as back in the Song period. Heavy snow is common. When spring arrives and the land heats quickly, most of Hebei experiences the “hot dry wind (ganrefeng 乾熱風),” which blows the earth so dry that it often kills winter-spring crops. The rainy season does not start until mid or late May. In general, precipitation is low throughout Hebei, with regional variations for annual rainfall between 400 and 600 millimeters. This small amount of rain nourishes the land in a peculiar way: about 70 percent of it hits the ground during three summer months, which creates downpours that fill up rivers, cause floods, and wash away the dry, loose soil from the land surface. During the rest of the year, the other 30 percent of the rainwater sprinkles down sparsely, far from enough to relieve aridity. This climatic pattern makes Hebei subject to certain natural disasters. Excessive rain causes floods, while a lack of rain causes drought. Historical records show that this seasonal contrast was evident in the Northern Song period as well as today.
Lastly, Hebei's geophysical singularity is also manifested in the characteristics of its water resources. Most of Hebei's natural streams originate from the western mountainous area. Supplied by underground water and snowmelts in spring, the rivers follow the smoot
h descent of the gradient toward northeast Hebei. In the vicinity of modern Tianjin where the land is lowest and was covered by swamps in the tenth to twelfth centuries, the rivers merge with each other before discharging into the sea. Back in the Northern Song period, some of these rivers were known for being muddy due to their heavy silt load. Their water volumes changed often and, due to Hebei's rain patterns, were prone to floods. Therefore, navigation by boat to travel from western Hebei downstream to eastern Hebei was a challenge.
Thanks to the flat low ground, water accumulates easily. Meanwhile, the underground water table sits merely 1 or 2 meters under the land surface; with even a little infiltration of rainwater, it rises quickly to form lakes, ponds, and springs. In early China, western and northern Hebei were festooned by extensive lakes. Many of them had shrunk or disappeared by the ninth century; the bottoms of these lakes had been cultivated as fields by farmers.29 With the addition of more water, however, these lowlands could still trap water and turn back into swamps and lakes. This is exactly what happened in the late tenth century. Under heavy rains, the local rivers ran wild and flooded, and a considerable portion of northern Hebei was submerged in stagnant water.
From the first century until the Yellow River's entry into the plain in 1048, Hebei's water system functioned as a largely independent, self-reliant entity. Rain, snow, surface runoffs, and the underground water circulated and replenished each other. These waters stretched toward every corner of the land to organize a vibrant, self-sufficient geographical entity, which formed the underpinning of the environmental life for both humans and non-humans on the Hebei Plain.