Category Water Engineering in Ancient Civilizations. 5,000 Years of History

The kingdom of Urartu, in the south of Armenia, was a powerful rival of Assyria during the period from about 850 BC to 600 BC. Its capital was Tushpa, on the shores of the lake Van, whose water is too salty to be potable. Therefore this capital city’s thirst led to the development of a vast water management program in this mountainous region, developed in successive stages (Figure 2.18).

In about 800 BC, the king Menua brought water to the capital from a perennial and abundant spring located some thirty kilometers to the southeast. The 56-km canal – aqueduct built for this purpose carried at least 1.5 m3/sec, and was destined to be used

for 2,500 years until it was partially renovated in 1950.

Later, probably about 670 BC, the king Rusa II[77] [78] moved the capital some ten kilome­ters to the north (Rusahinili, today Toprak-Kale). The two rivers that supply the two cities, the Engusner and the Doni, are intermittent. Therefore the sovereign created an artificial reservoir, the Rusa lake (today this is the lake Keshish Golti, whose water level is 10 m lower than at the time of king Rusa). The lake was created by damming two nat­ural outlets of a mountain basin. The north dam has been measured at 15 m high and 75 m long, and the south dam at 7 m high and 62 m long.

This south dam has been well preserved (it is no longer in contact with water, for the lake is now 10m lower). It is constructed of two walls of dry stone, each 7 m thick, con­taining an earth fill of thickness 13 m. Water is conveyed from this south dam to a secondary dam-reservoir on the Doni Cayi, in part to provide for irrigation of the Tushpa region. Later, other dams are built downstream on the two rivers, to increase the stor­age capacity.

Thus we see that the water management system of lake Rusa includes several dams. Over the centuries, the north outlet of the lake has apparently been destroyed and rebuilt several times, which may explain the existence of a dam attributed to Roman times, downstream on the Engusner Cayi. Its most recent reconstruction, lower than its origi­nal height, dates from 1950. The dam-reservoirs upstream on the Doni Cayi are still in service today. These are probably the oldest dams still in use[79] in the entire world.

The sovereigns of Assyria begin development of their land on the upper course of

Figure 2.15 Irrigation and water supply works in Assyria in the 9th and 8th centuries BC (after Jacobsen and Lloyd, 1935; Roaf, 1990; Schnitter, 1994; Bagg, 2000)

the Tigris in about 900 BC. This date marks the flowering of an Assyrian Empire des­tined to reign over all of Mesopotamia, and even as far as Egypt, for about three cen­turies. In 860 BC, Ashurnasirpal builds a new capital Kahlu (today Nimrud) on the left bank of the Tigris near its confluence with the upper Zab. A canal called babilat nuhshi (“bringer of abundance”) is dug to irrigate the plain with waters of the Zab diverted into the canal by a dam or weir.

It is interesting to note also that a ventilation system comprising chimneys (“air doors”) provides fresh air taken from the roofs of the royal palace to its grand rooms. But it is Sennacherib, the destroyer of Babylon, whom we are now going to see in a dif­ferent light. He was a lover of gardens. Since Khorsabad, the ephemeral city created by his father Sargon II, was too austere, Sennacherib re-adopts Nineveh as his capital. Taking advantage of his unlimited supply of manpower, he immediately sets out to acquire the water necessary for his horticultural aspirations (Figure 2.15). His first proj­ect, in 703 BC, is a 16-km long canal, fed by the Khosr, that brings water to the plain to the west of Nineveh. The waters of this canal, diverted into it by means of an overflow weir at Kisiri, irrigate orchards on plots allocated to the inhabitants of the capital through a lottery system:

. from the environs of Kisiri to the plain of Nineveh, across mountains and valleys, using iron picks, I dug a canal. Along a distance of one beru and a half (16 km) I took water from the river and made it flow down to irrigate the orchards.”[75]

Several years later, the area is in need of even more water. Sennacherib himself sets off into the mountains to see what springs existed. In 694 BC he had water tapped from the springs in the hills northeast of the city and brought to Ajileh, on the Khosr. The remains of two diversion weirs, constructed of large blocks of cut stone, are still visible there. But this new influx of water exacerbated the damaging floods in the Khosr. Therefore the king built a weir downstream of Ajileh to divert floodwaters into a canal going around the city to the south, and thence into artificial lakes. The king had plants and birds brought from the marshes of Babylonia, where he had admired them, to these lakes. The diversion weir was of serpentine shape, having a long crest length of 230 m that thus limited the rise of water during floods. The height of the weir itself was three meters.

But in the end even this additional water supply was insufficient, so its most spec­tacular feature was added to finally complete the system in 690 BC. Water was divert­ed from the Gomel, a tributary of the Zab to the north, and brought to the Khosr through a 55-km lined canal-aqueduct formed of lateral walls of cut stone crossing valleys on arches. At Jerwan (Figure 2.17) one can still see the remains of a magnificent bridge – aqueduct 275 m in length and 22m wide, crossing a valley by means of five arches each 4.75 m high. The diversion works on the Gomel at Bavian apparently included an oblique weir across the river. The canal, 6 m wide at its origin, passes through a short tunnel to cross a rocky spur.

Above the intake there are inscriptions that praise the hydraulic works of Sennacherib.[76] These inscriptions also describe an incident that occurred during the inauguration of the project, an incident that would surely have been very unfortunate for the engineers had the king not been in a good mood. The water pressure caused the closed gates to fail before they had been opened, allowing water to surge into the canal:

“To inaugurate the canal, I summoned the priests (…) and made offerings of lapis lazuli (a semiprecious stone), precious stones and gold to Ea, god of springs, fountains, and prairies, and to Enbilulu, god of rivers. I prayed to the great gods, and they heard my prayer. The gate yielded and let water enter in abundance. Even though the engineers had not opened the gate, the gods assured that the water found its way. After having inspected the canal and put things back in order, I offered sacrifices to the great gods (….) To the men who had dug the canal, I offered white linen cloth and colored woolens; I decorated them with rings and daggers of gold.”

This system is perhaps the first example of cross-basin water transfer.

It is also likely during the era of the Assyrian Empire that irrigation canals were con­structed on both banks of the Khabur, nearly continuously along the length of the river.

Elam, in the Susa region, is a very ancient civilization that developed expertise in hydraulic works starting in the IIIrd millennium BC. Three abundantly flowing rivers descend from the Zagros mountains and cross the region: the Kherka, the Ab-e Diz, and the Karan. Elam knew a brief period of glory when, between 1260 and 1160 BC, it took advantage of the weakness of the Babylonians to ravage lower Mesopotamia. Along with other spoils, the black stone on which is engraved the Code of Hammurabi passed through Susa at this time.

During this period Untash-Gal, sovereign of Elam between 1275 and 1240 BC, built a new city some forty kilometers to the southeast of Susa, next to the river Ab-e Diz; he gave the city his name in calling it Dur-Untash. But the course of the Ab-e Diz is below the elevation of the city, and the groundwater is brackish. So Untash-Gal dug a 100-km long canal to obtain water some twenty kilometers upstream of Susa from the Kherka, a river whose waters were known for their purity. The canal brings the water to a brick – lined reservoir just outside the wall of Dur-Untash. This reservoir, whose dimensions are 10.7 m long, 7.25 m wide, and 4.35 m deep, then feeds a basin just inside the city wall through nine openings. The city’s inhabitants could take water directly from this

basin.[74]

The city of Ugarit, on the northern Syrian coast (several kilometers to the north of the present-day Lattaquieh), has been occupied since very early times. It served as a mar­itime port for trade with Cyprus and Crete in the context of commerce among Mesopotamia, Mari, Aleppo, Ebla and the Mediterranean, and then as a port of the Hittite Empire of Anatolia. The city knew a period of great prosperity from the IInd mil­lennium BC until its final destruction in 1200 BC by the Sea People. The city is built on high ground, using wells for its primary water supply. As at Mari, rainwater is cap­tured on terraces and brought through gutters and vertical drops to the cisterns of hous – es.[72] The city is surrounded by two small temporary watercourses, the nahr ed-Delbe and the nahr Chbayye, on each of which there is a small dam; the dam on the nahr ed – Delbe is described in detail by Yves Calvet and Bernard Geyer (1994). The originality of this structure resides in its movable beams or stoplogs that can be removed to allow floods to pass. This is the first evidence of such technology that eventually became widespread.

More to the south, on the eastern slopes of the Anti-Lebanon mountains, is the city of Damascus. The city’s water-resource infrastructure is developed toward the middle or end of the IInd millennium BC, under the control of the Arameans. Two canals flow out of the Barada, the perennial river on which Damascus depended from Neolithic times. The system is eventually completed by the Romans and the Arabs (Figure 7.6) and remains operational to this day.

In discussing great cities and their infrastructures we must include Jerusalem. In the 12th or 13th centuries BC the Canaanites constructed a 537-m long tunnel to provide access, during sieges, to a reservoir on the flanks of a hill that is fed by an intermittent spring called Gihon (today called the “fountain of Marie”). Later, around 700 BC, Ezechias tapped this spring through an underground canal feeding a basin to the south of the city, known as the Pool of Siloam.[73]

The Zagros Mountains and their foothills from the 8th to 7th centuries BC: dams, aqueducts, and water supply for cities

We have seen that from the 13th century BC the political situation becomes very cloudy in all the Syro-Mesopotamian region. New powers rise to the east and north of the old lands of Sumer and Akkadia, at the foot of the Zagros mountains. The new power cen­ters move from the region of Susa to the east, up the course of the Tigris (Assyria) before returning to the east with the Persians. The incubators of these new powers are valley, hill and mountain regions whose springs and streams can be developed to provide high – quality water for the settlements.

At the Khanouqa gap on the Euphrates some 80 km upstream of its confluence with the Khabur, are the remains of hydraulic works.[69] This includes a rock weir, built of loose natural basalt blocks, damming the Euphrates so as to provide all-season water to a canal whose offtake is immediately upstream of the dam (Figure 2.13). The left-bank canal is called the canal of Semiramis[70] in the writings of the Greek traveler Isidore of Charax, dating from the first century AD:

“There is found the canal of Semiramis; the Euphrates is blocked by rocks so that, in its nar­rowed state, it floods the plain; but in the summer boats run aground there.” [71]

Remnants of the canal are partially visible in the vicinity of Khabur, along about 80 km. Navigation is clearly the main purpose of the canal, but it could obviously have also been used for irrigation. It is not possible to assign a precise period to these remains. Yves Calvet and Bernard Geyer suggest that the most likely period is from the end of the IIIrd millennium BC until the beginning of the IInd millennium BC. This is a period of prosperity for Mari, but does not exclude the possibility that the works date from a later time, in the Ist millennium BC (but the construction does not appear to be of Assyrian workmanship, and therefore we are inclined to favor the earlier hypothesis.)

Another project in the Mari region has left us with considerable evidence of its existence. This is the canal whose traces today are called nahr Daourin, with a width of 8 to 11 m, and a reconstituted length of some 120 km. Rising at Khabur, it joins the Euphrates downstream of Mari on the left bank, cutting into the cliffs in places (Figures 2.11 and 2.12). The canal has a fairly regular slope of about 0.2 m/km, though it is somewhat flat­ter in its upstream portions (0.12 m/km).[66] [67]

The letter of Yaqqim-Addu, from which we have cited extracts earlier, mentions the existence of a canal issuing from Khabur at Saggaratum, at the beginning of the IInd mil­lennium BC. This canal irrigates the Mari district on the left bank of the Euphrates, and is very likely the nahr Daourin. It was undoubtedly used for irrigation in particular given the context of the last years of Mari. But navigation was clearly the canal’s pri­mary purpose, as evidenced by its large cross section and length, and the fact that in

places it is excavated into the high banks of the flood plain. It is entirely possible that the project is closely related to the very founding of Mari in the IIIrd millennium BC. Indeed, it was from this period on that bulk material, such as the charcoal necessary for metallurgy, had to be brought down to Mari from upper Khabur. It is much easier to imagine the empty boats being hauled back upstream on a canal then on the irregular course of a large river. This hypothesis would explain the particular site on which Mari was founded – on the right bank on a road that leads to Syria, but near the downstream end of the canal. Suprum, where the canal bends toward the river on the left bank a lit­tle to the north of Mari, could well be the port where merchandise was transferred between the Euphrates and the canal. In connection with this navigation canal, there would have had to be a weir on the Khabur upstream at Saggaratum, to maintain the water level during low flow. But there are no longer any remains of such a weir.

The remains of another project of this type, including a weir across the river and a [68]

lateral canal, have been found on the Euphrates somewhat further upstream. This is the

canal of Semiramis.

About 2800 or 2900 BC, the Sumerians – or perhaps a people already established some­what to the north at Terqa – founded Mari, on the middle course of the Euphrates. The site is at the intersection of routes to the Syrian coast, near the outlet of the fertile valley of Khabur. This is not a village that has grown and evolved, but rather a “new city”. The region of Mari is completely arid, no agriculture is possible without irrigation. Yet 200 km to the north, at the toe of the Anti-Taurus mountains, one finds land that is naturally well watered. Therefore Mari must have been established where it is for reasons relat­ed to commerce and control of the waterway. The land of Sumer has to import raw mate­rial such as wood, stone, and metals. The early (and temporary) city of Habuba Kebira, further upstream, undoubtedly had the same needs. From the very beginning, Mari is a center of bronze metallurgy. Boats descending the Euphrates and the Khabur bring min­erals and charcoal to the city.[56]

Mari falls under the control of Sargon of Akkad around 2300 BC. Its period of greatest grandeur occurs under a dynasty of Bedouin origin (called Amorite), capital of a great kingdom of upper Mesopotamia between 1850 and about 1761 BC. In 1761 BC it sees its final destruction by the Babylonian Hammurabi, even though Zimri Lim, last king of Mari, had helped Hammurabi in his wars against Larsa, Esnuma, and Elam. The palace fire buried, and preserved to the present time, the clay tablets that comprise the archives of the last thirty years of the kingdom.

The city of Mari is essentially circular in shape, surrounded by a dike and wall. The city is 1 to 2 km distant from the Euphrates, for protection from floods and erosion. It is crossed by a canal that links it to the Euphrates at each end. This canal is 30 m wide,

and brings water to the city as well as providing access to the port of Mari.[57]

The city’s water supply is from the Euphrates, lifted into it by manual labor; women carry the water and fill the palace’s cistern (Figure 2.9). But in the palace of the IInd millennium BC there is also a network of brick conduits or pipes (Figure 2.10) that col­lects rainwater from the terraces to fill a reservoir.

In Chapter 1 we mentioned that Mari also benefited from a sort of drainage system, with sumps or cesspools for the drainage of rainwater and wastewater. This is evident from certain remains, as well as from palace texts:

“…On the subject of the sump, [….] according to the letter from my Lord, it is lined with asphalt from bottom to top. Over the layer of asphalt, there is a tar lining, and on top of that they put a coat of clay plaster.”

“After two rainstorms in succession, the sump was filled with water to a depth of a cane. The next day, they investigated it: 4 cubits of water had flown out. There remained 2 cubits, but they have already drained out ”[58]

Development of the land relies on major hydraulic works. Around 1850 BC, the sec­ond king of the Amorite Dynasty, Yahdun Lim, founds a fortress-city about a hundred

kilometers to the north of Mari, on the right bank of the Euphrates upstream of its con­fluence with the Khabur. He gives his name to the city, and endows it with a canal:

“Yahdun-Lim, the son ofYaggid-Lim, king of Mari, of Tuttul and the land of Hana, the strong king who rules the banks of the Euphrates; Dagan proclaimed my royalty (…). I opened canals, water-lifters were no longer needed in my country. I built the Mari wall and I dug its moat. I built the wall of Terqa and I dug its moat. Moreover, in the burning lands, in a place of thirst no king had been able to build a city, I, alone, had the vision and built a city. I dug its moat. I named it Dur-Yahdun-Lim. Then I opened a canal and named it Isim-Yahdun-Lim… ”[59] [60]

From texts cited further on, one can estimate that this canal is about 35 km long, a length necessary for the canal, with its flat slope relative to the Euphrates, to “raise" the water above the river to provide gravity irrigation of the crops. Traces of the canal remain visible today, but only in its upstream reaches.

Field studies2 7 have uncovered traces of other important canals near Mari (Figure 2.11). There is a large irrigation canal, six to seven meters wide and 2.5 m deep, whose remains can be detected along a distance of17 km. It is not entrenched, but for the most part is constructed of fill on the alluvial terrace by means of massive dikes, 2.5 m high and 50 m wide. This is probably the Mari canal mentioned in the archives of the IInd millennium BC. Extracts that we cite further on suggest that the canal ends some ten kilometers downstream of Mari, and that it is supplied by an intake on the Euphrates in the valley of wadi es-Souab. But it is also quite possible that the canal dates from a time preceding these texts, having its origin in a small dam whose traces have been identified on wadi es-Souab, to the west of Mari. This wadi, one of the most important seasonal tributaries of the Euphrates, has particularly abundant springtime floods. The dam, 19 km from the confluence of the wadi with the Euphrates, is 450 m long, 2.5 m high, and has two spillways.[61] There is yet another canal that could have provided drainage, between the city and the foot of the cliff. Mari could not survive without some degree of agriculture, and such agriculture was impossible without irrigation. Therefore it is nearly certain that all these canals date from the founding of Mari, around 2800 BC.

Written communications[62] [63] [64] found in the Mari palace include numerous descriptions of the work necessary to maintain the irrigation system. The water intakes are often blocked by silt deposits and the canals themselves encumbered with sediments and veg­etation that must be cleaned out annually. “Barriers”, apparently comprising tree trunks and branches, are placed to protect the intakes and limit deposits in their vicinity. Let’s listen to Kibri-Dagan, the governor of Terqa, in extracts from two different messages: “As for the work on the canal of Isim-Yahdun-Lim that I had to undertake the fifth of the month of Abum, I undertook it. It is considerable. I am going to proceed with considerable dredging. At this canal, the barrier-muba/litum that diverts the clayey silt toward the river is no longer there, and this has caused the canal to narrow near the river. (…) With my work­ers from the area, I am working on the interior of the canal. In ten days I will have cleaned out the reeds and brush down to Terqa, and there where the canal has narrowed, I will open it up again. I will be sure the work is done solidly so that the irrigation water will be blocked nowhere and so that the people can avoid famine.’0^

“At the end of the month of Abum, I gathered the servile and common people of my district and together with districts of Mari and of Saggaratum, I set out to open the blockage of the canal of Mari. However, before working on the canal of Mari, I used up all the water of the canal Isim-Yahdun-Lim for the upstream district, saying to myself: before the fields of the countryside of Terqa are irrigated, once water is available, the (upstream) district must be able to drink so that later on there will be no basis for protest.’01

Other correspondence gives indications of the manpower available for this work. At this time, Terqa can mobilize 400 workers. But for major undertakings, the order of

2,0 workers can be assembled, as the governor of Mari, Bahdi Lim, explains:

“Tell my lord: thus speaks Bahdi-Lim, your servant. Concerning the wadi of Der (on the right bank, downstream), we got going on the dead (?) intake works and the diversion canal. The administrative scribes calculated the amount of work necessary. Beyond the dead intake works, there is the work needed for the diversion. A crew of 2,000 people, that’s not much! After thinking about it, we go to work only on the diversion. The work that we have under-

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taken is good.”

The “barriers” mentioned above also play the role of raising the river’s water level at the intake to facilitate the outflow into the canal, without completely blocking the river. At this time there are six similar “barriers” on the Khabur designed to supply the irrigation canals. A letter from Yaqqim-Addu, governor of Saggaratum (whose supposed location is shown on Figure 2.11), describes these barriers and mentions a canal that pro­vides water to the left bank of the Euphrates from the Khabur as an important element of the region’s irrigation system:

“The Habur (i. e. the Khabur), like the canal of Isim-Yahdun-Lim and the canal of Hubur (on the right bank, the north portion of the canal of Mari?), is part of our irrigation system. The people who profit from this irrigation canal never undertake to maintain it, and they have not reinforced the weak spots. I had to take on six barriers (muballittum) — who else could assure they would be watched over? When one wants to take water for the ditches, right where the trunks form fences, it takes 3,000 bundles of brushwood to make a piled-up barrier. But this doesn’t raise the Habur (the Khabur) a single finger! One must put in posts to form the fence:

one makes brushwood during ten days: one then piles them up to form barriers. Today this sys-

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tem is damaged: alas! I am leaving for Habur; I am going to assess the damages.”

Later in this same letter, Yaqqim-Addu asks his colleague Dahdi-Lim, in charge of Mari, to loan him manpower, lacking which the Khabur flood will cause major damage: “At the present time, the Habur (the Khabur) is in flood at four cubits: it has covered all flood – able places. The dike-kisirtum that is upstream of the breach, downstream of the muballittu that we built, Kibri-Dagan and myself, had slipped. I am going to rebuild it. The side, at pres­ent, slipped again. I undertook to rebuild it. Moreover, the breach that we had closed up has reopened: two arches, made of brushwood, were installed. These various efforts have been considerable and have exceeded my means; my Lord needs to give instructions to Bahdi-Lim so that he will send me 200 men so I can reinforce the weak points on the Habur. If a breach occurs in the aforementioned dike, no one will be able to close it.”

One should not be surprised at how difficult it is to maintain these canals. As we have seen above, the slope of a canal must be less than that of the river, if the canal is to be used to irrigate terraces higher than the valley floor. The flow velocity must therefore be lower than that of the river, which favors the deposition of suspended silts in the canal.

The texts from Mari also show that fish farming is practiced at the beginning of the IInd millennium BC. The abandoned arms of the Euphrates are clearly exploited for this purpose, and it is again Kibri-Dagan who tells us about it:

“Tell my Lord, thus speaks Kibri-Dagan, your servant. When the river flood returned, the pond of Zurubban swelled and became larger than normal. This made me fear for the fish: there is a risk that the fish will leave the pond toward the river. Now a hundred people must come to make the water of the pond go toward the river.”[65]

Another text that we should cite tells us of a maneuver that makes the canal of Mari temporarily navigable, to carry boats loaded with grain from the harvest. All the second­ary canal intakes were closed to raise the level in the main canal. But this turned out to be a catastrophe, since the rising waters caused the dike to rupture, just as the governor of Mari, Sumu Hadu (predecessor of Bhadi Lim) was taken to bed, sick:

“Tell my Lord, thus speaks Sumu-Hadu: one had retained the water in the direction of Der: because of the boats that must transport grain, one had blocked, from the upstream, (all) the irrigation ditches, and the water level thus rose (in the canal). But yesterday, at nightfall, in the end the water opened a breach upstream of the bridge that is the intake with the Balih (here, the Wadi Der), there where there is a water conduit (uncertain translation: a device allowing water diversion). Immediately, despite my sickness, I got up, I harnessed my asses, and I went to turn aside the waters by a derivation system. Then I came back to stop the water in the Balih (the wadi Der). Early in the morning, I undertook to repair the damage: I am going to rebuild the water conduit (?), after which I will get to work compacting the soil. This breach caused an opening of two canes from top to bottom, on a width of four canes. By the first watch of the night, I will have finished blocking this breach and I will be able (again) to let the water pass. My lord should not worry! Moreover, I wrote to the various localities that I had turned aside the water during the night. At Appan, Humsan and Shehrum, the water was held in and there was not the least rise. As for me, I will be dealing with the sickness that I have contracted for a year!’OJ

All of these documents show that the leaders had strong personal engagements in the maintenance of the irrigation system. They called on specialists, likely trained from father to son, for positioning the gates, for the operational regulation of the network. The regions of Terqa and Mari are not the only ones in which such water management is practiced; further upstream the Balih is used to irrigate the region of the city of Tuttul during the Amorite period.

The mysteries of Jawa: the oldest known dams, on the slopes of Kjebel Druze (Djebel el Arab) – end of the IVth millennium BC

The site of Jawa, a hundred kilometers to the northeast of Amman in Jordan, is an enig­ma. It is an arid zone, in a desert of rough black basalt. The only source of water, apart from very infrequent rains, is the winter flood of a seasonal watercourse that comes down from Djebel Druze, the wadi Rajil. The site is somewhat off the track of commu­nication routes, but on the other hand it is easily defendable. Jawa had some 2,000 to

3,0 inhabitants toward the middle or the end of the IVth millennium BC. In this region [50] [51] where there had never been any settlements before, and where there will not be any new ones for several hundred centuries to come, these people built a fortified walled city, a citadel in essence. A British expedition, led by Svend Helms, explored the site between 1973 and 1976, and postulated that these people were refugees or migrants from some urban culture.[52]

For their water supply, the inhabitants of Jawa built an elaborate system that fills reservoirs with the runoff of winter and spring rains, and also with water diverted from the wadi Rajil during the floods of November and May. Three weirs on the wadi Rajil divert water into stone-lined canals that are several kilometers long and convey flow to ten reservoirs (Figure 2.6). Some fifteen gates control the capture and distribution of water toward either the multiple reservoirs, or toward irrigated fields. Three of the reser­voirs (Nos. II to IV, with a total volume of 42,000 m3) supply the city itself. Several other smaller reservoirs, totaling some 10,000 m3, supply animal pens. Cistern No. I, upstream of the city, is dug into a cavity of basalt. Open-air reservoirs Nos. VII, IX, and X are downstream of the city. One of the reservoirs (No. IV on the figure) is formed by a true dam, 4.5 m high and 80 m long. The dam comprises two stone walls confining a central impermeable earth core that is two meters thick (Figure 2.7). A hydrologic study has shown that the storage of water from the two combined sources (rainfall plus floodwaters of the wadi) could supply 3,000 to 5,000 inhabitants and their animals for an entire year.[53] The people of Jawa had even begun to raise the dam to a height of 5.5 m, and to build another similar reservoir along the course of the wadi Rajil itself. But these projects were destined to remain unfinished, as the city was abandoned after only fifty years of existence. The nature of the catastrophe that led these people to return to their desert wandering remains unknown to this day.

The hydraulic know-how seen at Jawa is not an isolated example. Somewhat later, around 3000 BC, semi-nomadic shepherds settle at the foot of the same mountain, 80 km to the north. Although they are not former city-dwellers like their earlier neighbors at Jawa, these shepherds are driven by the same preoccupation with their security, since they build a wall around their encampment. And like the inhabitants of Jawa, as soon as they arrive they master the same hydraulic techniques. Here, at Khirbet el-Umbashi (Figure 2.8), they form a reservoir in the bed of the wadi itself by building a dam right to the foot of the city wall. This earth dam, 30 – 40 m long, is later raised (as at Jawa) to reach a height of 6 to 8 meters. This reservoir then stores water brought from the two wadis to the north through a three-kilometer canal, as well as water from other direct runoff. An oblique weir, two kilometers upstream on the wadi Umbashi, diverts water toward another very large reservoir (some 30,000 m3) developed in a natural depression bounded by massive levees that attain heights of 2 to 3 m and a base width of 25 m.

At a neighboring site, Hebariyeh (in today’s Lebanon) one again finds the same kind of development, with a large watertight reservoir fed by diversions along a wadi and canals several kilometers in length. Unlike the ephemeral urban establishment of Jawa, these last two sites survive until about 1500 BC.[54] One can find additional remains of canals that collect rainfall along hundreds of meters of length[55] at other sites more to the west along the shores of the Dead Sea, from the beginning of the IIIrd millennium BC.

These hydraulic works represent the oldest known dams. It is impossible for them to represent merely local and isolated inventions. How could the new settlers at Jawa or at Khirbet el Umbashi have known how to construct, then and there, such relatively highly evolved hydraulic systems without having known of similar projects before? Therefore it seems clear that the construction of weirs and dam-reservoirs on intermit­tent watercourses had already become a technique known throughout the region from the end of the IVth millennium BC. The oasis of Damascus, occupied from Neolithic times, could have been at the origin of these techniques – though nothing is known of it during the period that interests us here. It should be remembered as well that the middle of the IVth millennium BC is a period of expansion of the Sumerian civilization. Habuba Kebira, with its highly perfected sewers, arises on the Middle Euphrates around 3500 BC, then is abandoned at some later date that could be close to the time of the founding of Jawa. With the beginning of the IIIrd millennium BC comes the period of the found­ing of Mari.

Hydraulic development involved not only the digging of canals, but also the restoration or maintenance of river courses. During the domination of Larsa in lower Mesopotamia (1932 to 1763 BC), it became necessary to rehabilitate the river system. The king Sin – Iddinam reestablishes the course of the Tigris, around 1845 BC, using paid labor:

“When An, Enlil, Nanna and Utu (Sumerian gods) blessed me with a good reign of justice and long days (…), to obtain fresh water for the cities of my country, (…), I fervently prayed to An and Enlil. They answered my fervent prayers and, by their absolute orders, charged me with the mission to dredge out the Tigris, to restore it (into its previous state) and to give the days of a long life to my name. So (…) I grandly dug out the Tigris, the river of abundance of Utu. I raised the top of the slope, the old embankment (…); I transformed the Tigris into a freely flowing water; I established at Larsa, in my country, an eternal source of water, a never-ending abundance. When I dredged the Tigris, the great river, the wages of each work­er were 3 ban (?) of Barley, 2 sila of bread, 4 sila of beer and 2 sicles of oil: this they received each day; nobody received more or less. With the strength of my country, I brought this proj­ect to a good end. With the reins and the decrees of the great gods, I restored the Tigris, the vast river, and I affirmed my good name for the far distant future.”[47]

A succession of kings of Larsa, in particular Rim Sim who was the last, dredged and reestablished all the fluvial system from Lagash and Larsa down to the sea. This reha­bilitation included the large branch flowing to the southwest on Figure 2.3 that supplies Bad Tibira and Larsa; this loop had been dredged earlier by the kings of Ur.

The floods of the Tigris and Euphrates, out of phase with the growing cycle of the grains, are more of a menace than a blessing. We know that the dikes or levees protect the cities and crops against floods, and stabilize the course of the rivers to the extent pos­sible. At Babylon, major works were accomplished to this end. Herodotus attributes these works to two queens:

“The first ruled five generations before the second; her name was Semiramis, and she built those dikes on the plain that are so remarkable to see; before that, the river used to run all over the plain and flood it.”[48]

In the eyes of the Greeks, Semiramis is a veritable legend. According to Georges Roux, Semiramis is possibly Sammuramat, an Assyrian queen who occupied the throne around 800 BC. All of the works mentioned herein (and especially the works described below) can also, according to Georges Roux, be attributed to the queen Naqia, the widow of Sennacherib. It is in fact eleven years after the destruction of Babylon by Sennacherib, a destruction that was considered to be a sort of sacrilege, that the son of Sennacherib undertakes the reconstruction of the city (this then puts us in 678 BC). But the biggest astonishment remains to come; let us once again listen to Herodotus:

“The second of these queens was called Nitocris (….) First, then, as to the Euphrates, which flows right through the middle of the city of Babylon. Formerly it was straight, but she made it so crooked, by digging canals above the city, that the river in its course comes three times to one of the Assyrian villages (….) This is what she did, she built an embankment along either shore of the river that is, in greatness and height, very wonderful in its dimensions. Far above Babylon she dug a basin for a lake, stretching it by the side of the river and a little away from it, and in depth she dug it always down to find water, and in breadth she made the cir­cuit of the lake to be fifty-two and a half miles (84 km) (….) She did both of these things – the making the river crooked and turning the basin into a marsh – so that the river might be slower, as it was broken by the many bends, and that the courses into Babylon itself might be crooked, and that then, after this, should come the long circuit of the lake. These works were built at precisely the point of her country where were the passes of entry and the shortcuts from the road out of Media, so that the Medes might not get into contact with her people and learn of her affairs.

”With these defenses she surrounded her city, but she added another work that grew out of them (….) For when she had dug the basin of the lake (….) she had huge stones cut, and when the stones were ready and the basin had been dug, she turned the entire stream of the river into the place that was dug. While it was filling, the old riverbed dried out; and she bricked with baked bricks, in fashion like to the walls, the banks of the river in the city and the descents from the gates leading down to the river (….) When the dug part had become a lake, filled by the river (…) she turned the Euphrates into its old course..”

This is a fine example of river engineering. According to recent work by Charpin (2002), the artificial lakes and dikes might in fact have been built by Samsuilina 1749­1712 BC, the successor of Hamurabi. If the account is correct, cut stone blocks were used for the difficult operation of blocking the river to divert water into the artificial lake. It is interesting to consider the roles of the meanders and the lake. The meanders effectively reduce the slope of the river, since the same drop is attained over a greater length. If the width and discharge remain the same, one can estimate that reduction of the slope by a factor of two, over a long length, will reduce the current velocity a little less than 25%, and raise the water depth in about the same proportions. Therefore it becomes necessary to raise the dikes. The lake, located upstream of the city, very like­ly plays a role in attenuating floods, capturing excess water through overflow when the river rises above a certain level.

The accounts of Herodotus include other examples of the Mesopotamian know-how in river course modification. Cyrus, the founder of the Persian Empire, suffered the loss of one of the sacred white horses of his team when crossing the Diyala (Gyndes to the Greeks). Furious at this affront to his power, he put his entire army to work for a full year (according to tradition) to break down the Gyndes into 360 small canals. Herodotus also reports that Cyrus (in 539 BC) enters Babylon without resistance using the hydraulic works described above:

“When he came to the lake, Cyrus dealt with it, and with the river, just as the Babylonian queen had done; he directed the river by a canal into the lake, which had become a marsh, and so, when the river had sunk, its old stream became fordable.”[49]

Once he had entered the city itself, Cyrus further extended the armoring of the banks. He didn’t miss the chance to commemorate this feat in carving the following inscription: “I added to (..) the banks protected by bricks, in the low-lying areas of the city, that a pre-

The importance of navigable waterways to the economy of Mesopotamia cannot be overestimated. The code of Hammurabi, from which we have already cited several extracts, includes laws that regulate navigation on the rivers and canals. It sets compen­satory payments for shipwrecks or breakdowns, and establishes right-of-way rules:

“If a boat traveling upstream collides with and sinks a boat traveling downstream, the owner of the sunken vessel will officially declare, in the presence of God, all that was lost in his boat, and the boatman of the upstream-traveling vessel that caused the sinking will pay for the boat and everything that was lost.”lz-

Several of the canals flow by gravity from the Tigris toward the Euphrates, reflect­ing the ancient confluence that existed in the IIIrd millennium BC in the region of Sippar (Figure 2.1). This did not go unnoticed by Greek observers, Herodotus in particular (this extract comes after the text cited earlier regarding irrigation):

“Babylon is in its entirety, like Egypt, crisscrossed by canals; the largest one is navigable, oriented in the direction of the winter sunrise, and joins the Euphrates to the Tigris, the river on which Nineveh is situated.”

According to Xenophon, four of these large canals are very respectable in size: “Here also are the canals, which flow from the Tigris river; they are four in number, each a plethrum wide (about 30 m) and exceedingly deep, and grain-carrying ships ply in them; they empty into the Euphrates and are a parsang (about 5.5 km) apart, and there are bridges over them.”1-3

These canals also have a strategic function in the context of the Assyrian domina­tion. The Assyrian capital Nineveh is indeed located on the Tigris as stated by Xenophon. At that time this river disappeared into the swampland and was not naviga­ble to its mouth. Therefore the canals between the Tigris and the Euphrates enabled boats to get to the Persian Gulf from Nineveh. In about 700 BC a flotilla constructed at Nineveh for the Assyrian king Sennacherib descends the Tigris to Opis; it then transits across to the Euphrates in anticipation of a military operation in the Persian Gulf. It is this same Sennacherib, exasperated by numerous revolts against the Assyrian power, who destroys Babylon in 689 BC – not only by fire, but also by water. He floods the city using a branch of the Euphrates, called the Ahratum, that flows out from Sippar.

But later on, in the age of the Achaemenid Persians, it is by contrast from the Persian Gulf that invasions were dreaded. The Persians were not sailors; they decided to block navigation on the Tigris and Euphrates by constructing weirs across them. They brought traffic to a standstill on the two great arteries of the country. When Alexander the Great later becomes master of the country, he removes these weirs as a gesture of liberation.[44] [45] [46]