Nineveh stood on the Khosr River just above its confluence with the Tigris. The engineering challenge was that the Tigris lay too far below the city to raise enough water for the growing capital. Instead, between 703 and 690 BC, Sennacherib undertook three separate projects to obtain more water via the Khosr. First, he dammed that river 10 miles to the north and diverted it to Nineveh through an open-air canal. When that didn’t provide enough water, he augmented its flow by damming and rerouting 18 small streams and springs from the hills 15 miles to the northeast. When that still failed to satisfy Nineveh’s growing thirst, in 690 BC his engineers built a masonry dam at an oblique angle across a deep gorge to divert the water of another river through 36 miles of winding channels to feed the Khosr. At one juncture, a massive 1,000-foot-long, 40-foot-wide stone aqueduct with five arches was constructed to carry the canal across a valley toward Nineveh. Among other sophisticated hydraulic features of Nineveh’s elaborate and integrated water system was the employment of a water-pressurized, U-shaped, inverted siphon pipe to carry water across and then up a topographical depression.
The Assyrians also institutionalized one of world history’s landmark breakthroughs in obtaining clean urban drinking water—the qanat. Originating in the hilly region of what is today eastern Turkey and northwestern Iran, qanats were long, deep, slightly inclined tunnels hewn through subterranean rock face into underground mountain aquifers and ran by gravity to lower-lying population centers. Being underground, they lost little water to evaporation—a major problem in hot environments. Their construction depended on iron tools and required sophisticated mining and engineering capabilities, including precise gradients and the cutting of vertical shafts for maintenance access and ventilation. The testament to the qanat’s great success was its ubiquity throughout central Asia and the Mediterranean rim, from southern Spain and Morocco to the west to northern India to the east. Romans built them when they occupied the region. They were mainstays throughout the realm of Islamic civilization. Spanish colonists introduced them, much later, in Mexico. Qanats even remained actively used into the twentieth century and provided much of Tehran’s water supply until the 1930s.
Since qanats required large quantities of water to be drawn from deep wells in a confined space, they encouraged the Assyrians to innovate improvements in water-lifting techniques based upon wheel-based pulleys. The spread of qanats overlapped the sixth century BC development of the earliest Greek aqueducts. Between them, ancient Middle East and Greco-Roman engineering tried almost every water supply technique aside from river water pumping used by civilization until the nineteenth century.
Sennacherib was famous in the Bible for his long siege of Jerusalem in 701 BC during the reign of King Hezekiah in response to a rebellion across Palestine against Assyrian hegemony. Jerusalem’s historical greatness in antiquity owed as much to its water supply as its strategic trade crossroads location. The city’s main water source was the Gihon Spring just outside its walls. Its pre-Hebrew occupants, the Jebusites, had connected the spring to the city by a 1,200-foot-long secret underground water tunnel to protect themselves against siege. Yet the tunnel became their undoing in about 1000 BC when King David discovered its whereabouts and Hebrew soldiers stole through it to take the city by surprise.
David’s successor, Solomon, promptly solidified the new kingdom by expanding the city’s water supply with three large external reservoirs to feed the city’s internal network of cisterns and rain-collecting water tanks. Keenly aware of this history as he fortified his defenses in anticipation of Sennacherib’s siege three centuries later, King Hezekiah ordered the digging of a new secret water tunnel underneath Jerusalem to transport water from the source of the Gihon Spring to a reservoir inside the city walls. Cut through sheer bedrock with a precise gradient, the 1,800-foot S-shaped tunnel has carried water almost continuously for 2,700 years. In the event, all the rebel strongholds except Jerusalem fell to Sennacherib’s soldiers. Failing to find the hidden Gihon Spring or the secret water tunnel, the Assyrians decided to withdraw after Hezekiah agreed to pay a heavy tribute as reparation.
One rebellious city that did not escape Sennacherib’s vengeance was Hammurabi’s fabled Babylon. In 689 BC he overran the city after a fifteen-month siege, looted its treasures, massacred or deported the population, and reduced its main buildings to rubble. He prepared to seal its doom by flooding it with waters diverted through channels dug from the Euphrates. At the last moment, however, Sennacherib’s son rescinded his father’s plan in deference to the city’s storied past; as king, he later rebuilt the city in an effort to wed Babylonians agreeably to Assyria. His leniency proved to be a grave political mistake. Within less than a century, Babylon had risen again, leading the overthrow of Assyria’s empire and sacking many of its great cities.
Babylon’s revival reached its zenith under the reign of King Nebuchadrezzar II from 605 to 562 BC. Nebuchadrezzar rebuilt the fabled city with the concept that it was the organizing, renewing center of the chaotic universe, with resplendent ornaments within and without its immense, 10-mile walled perimeter and majestic gates. These included the spiraling ziggurat known in the Bible as the Tower of Babel and one of the ancient world’s seven wonders, the Hanging Gardens. The mechanically watered gardens were built by Nebuchadrezzar to please his Medean wife, who longed for the forested hillsides of her youthful home in what is now Iran. They are believed to have consisted of a series of terraced roof gardens of overhanging trees and plants rising on a mountainlike palace of stone balconies. Irrigation water was lifted in pots from the Euphrates by a tall noria waterwheel powered by man or animals, and flowed down from terrace to terrace. The stones were waterproofed, as were the walls of Babylon itself, against seepage by the use of viscous, tarlike bitumen.
Babylon’s imperial revival did not long endure. The city finally met its doom on October 12, 539 BC, when it was overrun by the region’s rising new superpower, the Persian Empire of Cyrus the Great, in the aftermath of Cyrus’s major victory over the Babylonian army at the confluence of the Tigris and Diyala rivers—one of the many battles in history to be fought at strategic riversides. In an uncorroborated history of Herodotus, the city’s denouement came after a long, fruitless siege when Cyrus tried one last stratagem—manipulating the Euphrates River, which ran straight through the center of Babylon and presented the only soft point in its formidable defensive walls. He stationed troops near the river’s entrance and egress from the city. Upriver, other soldiers excavated a large diversion channel that redirected the river’s flow away from the city. As the river’s level to Babylon fell to “only deep enough to reach about the middle of a man’s thigh,” the Persian army waded across and successfully breeched the city’s floodgates before the Babylonian defenders inside realized what was happening.
Cyrus and his successors, including Darius and Xerxes, built the world’s largest empire, stretching from the sands of Libya to the Jaxartes (modern Syr Darya) and Indus rivers in Asia, an area about the size of the continental United States. Its center was in the high Iranian plateau at Susa, east of Mesopotamia. They adopted and advanced hydraulic methods throughout their domain. They revitalized Mesopotamia by widening the irrigated cropland with a new grid pattern of canals, many of which were navigable by barges. An army of slaves dredged the waterways of silt. Salinization and waterlogging problems were mitigated by planting weeds when land was fallow to lower water tables and by trying not to overirrigate. As in classic hydraulic societies, the Persian sovereign visibly supervised big hydraulic operations, including allocation of irrigation water, which was distributed, in principle, to those who needed it most. It was they who introduced the water-lifting noria to Egypt, and who made the first systematic attempts to dam the main channels of the Euphrates and Tigris by constructing artificial cataracts as impediments to naval invasion from upriver; Alexander the Great, in his conquest of Persia two centuries after Cyrus, systematically removed many of them.
Herodotus also reports th
at wherever the mighty Persian king and his armies traveled within his empire, he was careful to drink only water, properly boiled, from one single river near Susa. “No Persian king ever drinks the water of any other stream,” Herodotus wrote, “and a supply of it…is brought along in silver jars carried in a long train of four-wheeled mule wagons wherever the king goes.” Whether apocryphal or no, Herodotus’s assertion highlights the very real dangers posed by drinking water from any unknown source, as well as ancient beliefs in the mystical powers of regeneration and purification ascribed to special water sources.
Until its fall to Alexander, the mainly land-based Persian Empire was the unrivaled power of the age. The chain of events leading to its ultimate undoing, however, started with its failure a century and half earlier to vanquish the upstart naval power of small Greek city-state Athens.
In the Indus River valley of modern Pakistan, and later along the Yellow River in China, advanced ancient irrigated agrarian civilizations developed with familiar hydraulic patterns along flooding, silt-rich, navigable rivers in semiarid landscapes where precipitation was too sparse and unreliable for large, rain-fed farming. Until the 1920s, the advanced ancient Bronze Age civilization that thrived along the Indus from about 2600 to 1700 BC was lost to history. Its very existence had been discovered only accidentally when British railroad builders in colonial India unearthed some ancient bricks. Excavations revealed an enormous city of 30,000 to 50,000 inhabitants buried under centuries of Indus mud. Mohenjo Daro, on the lower Indus, was as large as any Mesopotamian city of its day and laid out in a carefully planned, rectangular grid with an elevated defensive sanctuary and a lower level. Later archaeologists uncovered scores of settlements and cities clustered along the Indus and the Arabian Sea shoreline of an entire lost civilization. They found a second, nearly identically designed giant city, Harappa, on a dried-up Indus tributary upriver in the Punjab (“the land of five rivers”), as well as a large port city linked to the sea by a mile-long canal. In all the Indus civilization occupied an area larger than its Mesopotamian or Egyptian contemporaries.
The character of this civilization remains enigmatic. Its pictorial right-to-left written language is undeciphered. But it far antedates, and has no linguistic link with, the Sanskrit of the ancient Vedas and subsequent Hindu Indian civilization that inherited its domain. By every indication it was a classic hydraulic society. Its centralized, redistributive organization was suggested by the existence within its brick-built cities of capacious granaries for wheat and barley. The endemic malaria detected in the unearthed skeletal remains was a signature of the disease-bearing mosquitoes that bred in the standing water of irrigation channels and afflicted hydraulic societies everywhere. Typical of monsoonal habitats, irrigation methods apparently involved the storage of water during the wet season for release in the dry months. Trade artifacts show that the Harappan civilization probably had extensive sea trade contacts with Mesopotamia from very early on, and it is likely that Sumerian civilization had a similar stimulating impact upon its rapid growth as it had upon Egypt.
The Indus River & India
Among the Indus civilization’s most intriguing features was its advanced urban hydraulics, which anticipated developments in ancient Rome by 2,000 years and the nineteenth-century sanitary awakening by 4,000 years. Its communal Great Bath at Mohenjo Daro, located in a building’s inner courtyard and sunken into a platform with entry stairs at either end, was a deep, large tank about the size of an average modern swimming pool with its own water supply and drainage channels, and waterproofed with bitumen. Whether it was used for ritual purifications as in later Hindu rites, hygiene, or social gatherings as in Roman baths is unknown. But its linkage to the extensive, underground municipal sewer network, indoor toilets, and water wells in its many two-story houses reflected a precocious understanding of sanitary water supply and waste removal that would be later rediscovered elsewhere as a necessary cornerstone of urban civilization.
Perhaps the Indus civilization’s greatest mystery was why it suddenly disappeared from history around 1700 BC. It used to be thought that its abrupt demise was due to its being overrun by the invasion from the northwest of light-skinned, fair-haired, Indo-European Aryan horsemen and charioteers, cousins of the Germanic, Celtic, and Hellenic warriors, whose descendants eventually established the Vedic Hindu civilization both in the Ganges and the Indus river valleys. Yet by the time of the Aryan invasion, the Indus civilization seems to have been in severe decline. The main culprit, instead, was likely its unpredictable, fragile hydrological environment.
The Indus valley was fed by two main water sources: snowmelt from the surrounding Himalayas and Hindu Kush Mountains to the north and west, and the intense deluge of the seasonal, highly variable monsoon. Rapid silt buildup in the flat floodplain made the Indus region highly prone to violent inundation. Like the Euphrates, the river’s notoriously errant tributaries frequently abandoned their channels to carve new routes to the sea. Increasing regional desiccation from climate change, with steady encroachment from the Thar Desert in the east, added to the hydrological fragility. From about 2000 BC, the Indus region appears to have been ravaged by many massive, destructive floods. Many dry riverbeds, including once-great tributaries of the Indus—and possibly a vanished twin river—provided widespread evidence of rivers that had radically changed course, forcing large towns and farms to be abandoned. Mohenjo Daro itself was rebuilt at least three times. In the end, unpredictable flooding, droughts, soil salinization from irrigation, and rising water tables likely undermined its sustainable prosperity and caused its population to decline and emigrate.
The Indus civilization’s fall fit a common historical pattern. The vanished, 50-mile-long irrigation canals along the Moche and Chicama rivers in pre-Inca Peru, the large spiderlike canal systems built by the Hohokam, or “gone people,” native Americans in modern Arizona between AD 300 and 900, and the lost Pueblo societies that succeeded them there testified to the similar fate of many irrigation societies located in water-fragile habitats when subjected to water shocks, including long or intense periods of climate change. Ancient Petra, the rock-carved city in modern Jordan, based on seasonal wadi agriculture and caravan trade, collapsed in AD 363 when an earthquake destroyed its elaborate, cistern-based water system.
The Maya in the rain-fed, poor soils of the seasonal tropical forests of the Yucatán Peninsula ingeniously built an advanced corn-and-beans-based civilization between AD 250 and 800 upon fragile water foundations marked by pronounced unpredictability of winter aridity and little perennial surface water. They did so initially by slashing and burning fast-regenerating vegetation and then, with greater productivity and population size, draining and dredging an array of irrigation canals and farming on raised earthen mounds and hillside terraces. They also carved deep, underground cisterns in the porous limestone bedrock to store fast-collecting, seasonal groundwater runoff for year-round domestic needs. The Mayan civilization’s rapid collapse and 90 percent population decline in three stages after AD 800 was likely propelled by several interrelated depletions that undermined its water resource engineering: deforestation from hillside farming as population pressures grew triggered soil erosion that cluttered its jungle canals and farming mounds with poorer soils and intensified regional aridity during dry seasons; as farm productivity suffered, internecine warfare for food increased among neighboring communities; the final blow was probably the onset of the worst long-term drought cycle in 7,000 years. The geographic pattern of collapses across the Yucatán Peninsula closely tracked the diminishing availability of accessible stored groundwater.
When high civilization was reborn in India about a millennium later following the arrival of iron, it was centered first in the Ganges River valley, an altogether different habitat characterized by luxuriant forests, heavy, monsoonal rainfall, and a river system that carried several times more flow than the Indus. The iron ax was the key innovation that cleared the jungle, followed by heavy plows pulled b
y eight oxen or more to turn the fertile soil for planting. From about 800 BC, monarchies with hydraulic-state attributes based increasingly on large-scale rice cultivation that could sustain denser populations began to take hold along the Ganges from valley to delta. Increasingly powerful, centralized authorities directed the skilled and labor-intensive chores of timely field flooding and draining, water storage, diking, and building and maintaining canals and embankments.
In time India’s two monsoons produced two harvests, which doubled rice’s intensified productivity. Over the centuries Indians developed esoteric arts for trying to read cloud patterns and ocean signals to anticipate the onset of the monsoons, which was critical for the timing of planting and the feeding of India’s population. To the present day, no satisfactory solution has ever been found to the unpredictability of the monsoon’s start date and the extreme variability of its volume, which remain the largest single variables in India’s economic growth.
Ultimately, all of the northern half of India, from the semiarid floodplains of the Indus to the moist Ganges valley to the soggy deltas where the giant Ganges and Brahmaputra rivers spill into the Bay of Bengal, was united through the conquests of the “Indian Julius Caesar,” Chandragupta, founder of the Mauryan dynasty that established India’s first golden age, from 320 to 200 BC, in the aftermath of Alexander the Great’s retrenchment from the Indus. In a pattern of declines and restorations reprised throughout history, a second Gupta golden age, likewise hallmarked by large-scale, centralized waterworks, flourished from about AD 300 to 500 in the reunification of these distinctive, hydrological environments. To cope with the seasonal extremes of the monsoons, Indians from this period onward, particularly in the west, began to build hundreds of distinctive, elaborately carved, templelike stepwells, three to seven stories deep, that women and children descended to retrieve water stored from diluvial periods.
Steven Solomon Page 6