The Western Roman Empire’s final demise accelerated in the late fourth century AD. The proximate cause was a new wave of incursions by Gothic and other barbarian tribes put to flight by the invasion into eastern Europe from the central Asian steppes of a fearsome, nomadic tribe, the Huns. The Huns, who eventually settled in the Danube valley, themselves had been propelled into motion by their own ejection from their Asian homelands by an even more warlike group, the Mongolian Juan-juan war confederacy, which also constantly menaced China. By AD 410, when traitors opened Rome’s gates to Alaric, the Visigoth leader, for the traditional three days of sacking, the imperial Western seat of its government already had fled to safety at Ravenna, where the mucky coastal marshlands afforded better natural defenses from cavalry and barbarian armies.
Rome’s aqueducts also figured prominently in the city’s subsequent history and its ultimate renaissance as a center of world civilization. In the mid-sixth century, Byzantine Roman emperor Justinian made a major effort at revival when he tried to retake Italy from the Goths. The Eastern Empire had prospered from its seat at Constantinople and even had launched a formidable new navy. Justinian assigned the exceptionally talented general Belisarius to undertake the recovery of Italy. In 536 and 537, Belisarius successfully conquered northward from Sicily, took Naples by sending 400 soldiers undetected through an aqueduct he had drained during the siege, and then entered Rome without a fight when the Goths evacuated it as indefensible. Destroying Rome’s aqueducts was one of the first targets of the Goths in their countersiege against Belisarius. Water ceased to flow almost everywhere; baths, drinking fountains, basins, and sewers went dry. Citizens were forced to crowd into the low-lying areas closer to the Tiber and rely upon the river and wells for their freshwater. The cutoff of the aqueduct flow also shut down the big waterwheel-powered gristmills on the Janiculum, the steep hill near the modern Vatican where much of the city’s daily bread was produced. The ever-resourceful Belisarius responded by constructing floating water mills, moored between two rows of boats, under the Tiber bridges where the currents are artificially accelerated—such floating water mills later became commonplace under medieval European city bridges. The Goths tried to jam or break the waterwheels by throwing the bodies of slain Roman soldiers and tree trunks into the Tiber, but Belisarius thwarted them by laying a protective chain across the river to catch the debris.
The Goths also secretly probed the empty aqueduct channels in the hopes of gaining surprise entry into the city. They might have succeeded had not a Roman sentry at the Pincio Hill gate glimpsed the flickering torch light of Goth soldiers as they passed a shaft rising to the surface from the subterranean channel of the Aqua Virgo. The sentry concluded he had seen the gleaming eyes of an errant wolf. Belisarius, however, insisted on an investigation that exposed the Goths’ incursion. He ordered the sealing up of all the aqueduct channels. After defending Rome, Belisarius moved north. In AD 540 he took back Ravenna, which the Goths had made their capital. His success and growing popularity, however, made Justinian uneasy about his ambitions. He was recalled. In the end, Justinian’s dreams of imperial restoration scarcely outlived him. A new wave of barbarian invasions, this time led by the Germanic Lombards, soon overwhelmed Italy.
By the end of the sixth century, with most of its aqueducts and sewers in ruins and its buildings crumbling, as Rome biographer Christopher Hibbert describes it, “Rome’s decay was pitiable…the Tiber carried along in its swollen yellow waters dead cattle and snakes; people were dying of starvation in hundreds and the whole population went about in dread of infection…The surrounding fields, undrained, had degenerated into swamps” infested with malaria-bearing mosquitoes. The city’s population had shrunk to only 30,000. An anti-Lombard alliance between the Papal States and the Frankish Carolingians—reaching its apogee in AD 800 with the St. Peter’s Christmas Day coronation of Charlemagne as Holy Roman Emperor—and a papal effort to marshal peasant labor to repair some of the aqueducts failed to endure. By 846 Muslim pirate vessels traveled up the Tiber and plundered St. Peter’s.
The Mediterranean West’s free-market seafaring and republican democratic traditions, however, were not totally extinguished on the Italian peninsula. Instead, they were transplanted after AD 400 to a cluster of islands in a very shallow 200-square-mile saltwater lagoon intersected by a few deep channels at the head of the Adriatic Sea to which prosperous Roman citizens from the countryside had fled for safety from the barbarian marauders. Venice was destined to become the most precocious of the early Italian city-states, the preeminent sea trading and naval power in the Mediterranean, a progenitor of the modern market economy and the longest lived democratic republic in world history. By AD 466 the dozen tiny island communities began to elect representative tribunes to coordinate affairs among themselves. The first doge, or duke, was elected ruler in AD 697 in what would be an unbroken line of democratically chosen successors until the Venetian republic was finally overrun 1,100 years later in 1797 by French conqueror Napoléon Bonaparte.
Venice lent its nascent naval power in the Adriatic to assist Belisarius and the Byzantine Empire, in what would become a long, complex, competitive alliance between the two greatest sea powers of Christian civilization in a Mediterranean soon threatened by the ascendant commercial and military forces of Islam. It was through Venice that the historic bridge of continuity was established between the early republican seafaring trading traditions born in the ancient Mediterranean and the sea-oriented, liberal market democracies that later rose to world preeminence in post-Renaissance western Europe.
The revival of the city of Rome itself began in 1417 with the end of the Great Schism and the return of the reunified papacy to Rome in the person of Martin V. For want of drinking water, much of Rome’s population at the time was still clustered in ramshackle houses close to the filthy Tiber. One of Martin’s earliest acts upon returning to Rome was to repair the still partly functioning Virgo Aqueduct that had eluded total destruction by the Goths. Over the next two centuries, several of Martin’s successors, notably including Nicholas V, Gregory XIII, Sixtus V, and Paul V—known collectively to historians as the “Water Popes”—dedicated themselves to rebuilding Rome’s water system and adorning it with the high Renaissance fountains still admired today. As the water returned, so did Rome’s population and the city’s grandeur. Rome’s population doubled to 80,000 by 1563, reached 150,000 in 1709, and rose to 200,000 by the time of the birth of the Italian state around 1870. Fittingly, the last pope before Rome’s integration into democratic Italy completed the redesign of the Republican-era Marcia aqueduct, which became Rome’s first to operate under modern-era pressure with pumps.
CHAPTER FIVE
The Grand Canal and the Flourishing of Chinese Civilization
Although intensive irrigation society developed latest in China among the river-born, cradle civilizations of antiquity, its water management achievements surpassed all the others. China’s inventive, adaptable, and wide-ranging water engineering responses to its diverse environments was the foundation of what became the most precocious, preindustrial civilization in world history. “The Chinese people have been outstanding among the nations of the world in their control and use of water,” observed Joseph Needham in his classic Science and Civilisation in China.
China’s ancient civilization arose in a landscape markedly different from other hydraulic societies. It began in the semiarid inland north where the Yellow River in its middle reaches exited the barren steppe highlands of Mongolia and carved a large bend through plateaus covered with deep deposits of soft, flakey, yellowish rich soil, called loess, left by the receding ice age. The climate on these stark plateaus, larger than the size of California, was harsh: frigid in winter, scorching hot in summer, prone to droughts, dusty whirlwinds, and occasional summer downpours that eroded the soft cliffs and washed its loess soil into the Yellow, choking it with the thick silt that gave the river its name and enriching the north China floodplain into which it spill
ed. Yet the plateau’s combination of ample river water, easily farmed and drained soils, and military defensibility provided fertile conditions for a single season of intensive, field grain agriculture. The best adapted crop was millet, a tough grain capable of surviving prolonged dry periods. Gradually, farming was extended throughout the large, loess-enriched, northern floodplains. Most extraordinarily, however, China’s civilization achieved the rare accomplishment of hurdling its geographic origins over time to transplant itself far beyond its mother river region to a radically different habitat south of the 33rd parallel dominated by the voluminous Yangtze River. In contrast to the semiarid north, the Yangtze region was rainy, humid, verdant, mostly hilly, heavily monsoonal, and civilized by the intensive cultivation of an entirely different crop, wet rice.
The outstanding, transformational event that catapulted Chinese civilization above all its contemporaries, and marked one of water history’s turning points, was the completion in the early seventh century AD of the Grand Canal—still mankind’s longest artificial waterway, extending over a distance equal to that between New York and Florida. The south-north-running canal linked China’s two disparate, giant river systems and habitats to create the world’s largest inland waterway transportation network. Just as the Nile had unified Upper and Lower Egypt, China became integrated into a militarily defensible nation-state with a strong, centralized government that commanded an expansive diversity of highly productive economic resources. The Grand Canal played a catalytic role not only in China’s becoming the world’s most precocious civilization during the Middle Ages but also in the country’s fateful fifteenth-century decision to turn its back on the rest of the world that ultimately led to its prolonged, slow decline.
The Grand Canal was so successful because it bridged China’s underlying hydrological fault line: north China’s chronic insufficiency of accessible freshwater resources to fully irrigate its superabundance of rich soil to achieve its maximum food-growing potential, and south China’s opposite profile of having more water than could be productively employed on its less fertile soils. Managing this north-south water and land resource mismatch has been a recurring, central technical and political challenge of Chinese governance in every era since imperial times.
Both the 3,400-mile-long Yellow and the 3,915-mile-long Yangtze originated in the Tibetan plateau in the Himalayas. Beyond that their signature flows and environmental characteristics diverged sharply. The Yellow was shallow and by far the world’s siltiest river—30 times siltier than the Nile and nearly three times more than the famously muddy Colorado River. A dipperful of its water was commonly said to contain 70 percent mud. It was the rapid buildup of eroded silt from the loess plateaus that caused the Yellow to frequently overflow its banks in unpredictable, devastating floods across its lower plains. So many millions perished and lost their livelihoods in these fearsome floods over the centuries that the river became known as “China’s Sorrow.” Its greatest floods—some carving new paths as far as 500 miles away to the Yellow Sea—repeatedly fomented political and economic upheavals throughout Chinese history. Building tens of thousands of miles of levees to try to contain the Yellow within its banks, and rebuilding them after the inevitable failures, was thus always a top political priority of every Chinese dynasty.
The huge Yangtze, by contrast, carried some 15 times more water than the Yellow, with deep navigable channels and many large tributaries that made it an ideal transport highway for large vessels once its waters had descended the mountains and wound its way through its deep canyons and gorges to enter its enormous lower basin and swampy delta. The Yangtze’s seasonal monsoon floods regularly inundated the region; every half century or so, however, the combined rush of descending water and the engorged flow from its tributaries created giant waves that overwhelmed all man-made flood control infrastructure and resulted in devastating floods. When China’s climate was moister in ancient times, the central section of the Yangtze had been a gigantic swamp, far too wet to sustain large-scale civilized human settlement. Gradual desiccation, and Chinese advances in water redirection, terracing, drainage, and other wet rice irrigation techniques gradually transformed the region into prosperous farmland. By medieval times it was producing the greater part of China’s food, with rice surpluses distributed along its extensive tributary network and to the Yellow River region in the north via the Grand Canal and coastal sea routes. Political control of the “golden waterway” of the Yangtze thus joined flood control as a vital linchpin of Chinese power. So closely correlated was river management and governing power that the very Chinese character for “politics” is derived from root words meaning flood control.
China
The Silk Roads
The traditional founding father of China’s Yellow River civilization was Yu the Great. A water engineer, Yu rose to power on the merits of his accomplishment as the tamer of the great floods that ravaged settled life in the Yellow basin before recorded history. By having “mastered the waters and caused them to flow in great channels,” he made the world habitable for human society. In honor, the tribal confederation elevated him to leadership. He went on to found the Bronze Age Xia dynasty from about 2200 to 1750 BC, and he became venerated as the lord of the harvest in association with the river’s early irrigation works.
Yu’s legend reflected the paramount importance of water control in Chinese history. At birth it was said he emerged, fully formed, straight from the dead body of his father, who had previously tried and failed to control the floods by damming and diking the river’s flow, and had been put to death for stealing magic soil from heaven in order to build a dam. After careful study and surveys, Yu took up his father’s task by the different approach of laboriously dredging river channels and digging ditches and canals, including one bored through a mountain, in order to divert excess floodwaters to the sea. He labored selflessly alongside the workers, and after many years, finally succeeded in bringing the Yellow River and its floodplain under control. Confucius hailed him as the ideal of the humble, qualified government official who used his power for the public good, and thus the aspiring role model for China’s technocratic elite who governed in support of its emperor.
Water management helped frame the historic Chinese philosophical debate about the right principles for man’s governance of himself and his relations to the natural order. The sixth century BC Taoists argued that humble water’s yielding, yet relentless flow that wore down all hard and strong obstacles expressed the essence of nature and provided an exemplary model for human conduct. Taoist engineers designed waterworks to allow water to flow away as easily as possible, exploiting the dynamics of the natural ecosystem, just as they urged Chinese leaders to gradually win support for their goals through persuasive dialogue. Their main rivals, the Confucians, on the other hand, advocated a more forceful manipulation of both nature and human society to achieve the public good. They believed that rivers had to be forced, through dikes, dams and other obstructive constructions, to do man’s bidding as defined by rulers and technocrats. Although the Confucian view prevailed as the guiding tendency of Chinese hydrology from the Han Empire in the late third century BC to the twenty-first century postcommunist state, the underlying principles framed a fundamental engineering debate which has reemerged on the global level today as the world seeks environmentally sustainable solutions to the water scarcity crisis.
After nearly half a millennium, Yu’s Xia dynasty was displaced as the predominant power by the Shang and later the Zhou dynasties. Each was centered along a different, but overlapping part of the inland Yellow basin and flourished on indigenous irrigation agriculture without significant river or seaborne trade with other regions. The Shang was a Bronze Age tribe that with the help of the chariot imposed an aristocratic rule from about 1750 to 1040 BC over an area centered in the fertile north China plain and within reach of the Yellow River region’s tin and copper deposits. Although they were one of the earliest literate cultures east of Mesopotamia, t
he Shang’s many primitive customs included ancestor worship, human sacrifice, and various ritual consultations with the spirits by priestly diviners. The excavations at their city of Anyang yielded tens of thousands of “oracle bones” that were consulted by priests to reveal answers to the vital questions of life and death such as whether it would rain or when the barbarians from the north would attack.
North China’s climate was still much warmer and moister than today, and large-scale irrigation depended on extensive reclamation of cropland by draining fens and marshes by mass organized manpower. Their highly stratified social organization and large public works, including extensive walled cities, fit the model of the hydraulic civilization. Startling confirmation that millet was one of their staple crops was made in 2005 when archaeologists exploring the remains of an ancient village buried by an earthquake and flood discovered a bowl containing a well-preserved 4,000-year-old millet noodle 20 inches long.
With the conquest and amalgamation of the Shang culture by its former vassals, the Zhou dynasty, centered on its western border along a tributary of the middle Yellow River, more of the distinctive character of the emerging Chinese state took shape. While retaining the older dynasty’s use of kinship as the basis of political organization, the Zhou introduced the enduring political concept that the emperor’s ruling legitimacy stemmed not solely from divine right of birth but from a “Mandate from Heaven” based upon moral performance. Water control was a key test of the mandate. A good emperor was expected through magic and ritual to be able to deliver vital things like rain, peace and good harvests; droughts and floods, on the other hand, were events that signaled heaven’s disapproval. One legitimizing boon to Zhou crop irrigation was the innovation during their reign in the sixth century BC of productivity-enhancing iron tools. The advent of iron, however, also stimulated the deployment of new weaponry. From about 400 BC, what would emerge as the unified Chinese state was forged over nearly two centuries of incessant warfare between seven competing regional powers. During this period, the flight of northern farmers from the war zones accelerated the migration of Chinese civilization to the cultivation of rice paddies in the warm, wet south. Although China’s rice farming would not achieve its full critical mass until the seventh century AD, by the time the Ch’in dynasty consolidated its victory over its rivals in 221 BC—giving China its modern name—its domains extended throughout the Yangtze basin to the eastern seaboard.
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