Bart Schultz
In one of my previous contributions to Flevolands Geheugen on Irrigation and Tells in Mesopotamia, I mentioned that this polder must very likely have to be located in the downstream part of Mesopotamia. In that context, I came across two interesting articles by Carrie Hritz et al. (2012) and Carrie Hritz and Jennifer Pournelle (2014), respectively.
These articles describe how the flourishing of the early Sumerian civilization exhibited a degree of economic differentiation, socio-political complexity, and urbanization unprecedented in the ancient world. Hritz and Pournelle argued that there were three complementary resources in the area that offered an advantage and thus laid the foundation for these developments: 1) vast irrigable plains; 2) vast pastures; 3) coastal areas containing swamps behind levees and delta swamps.
In the articles, the authors presented the results of research in the area of the Hawr al-Hammar marshes and provided a brief description of three types of areas.
The first, most upstream area, with Baghdad in the North, the current course of the Tigris in the East, the Euphrates in the West, and the ancient city of Kish in the South, was characterized by naturally branching river arms and canals, intensive agriculture, and irrigation. The elevation difference over a distance of 100 kilometres between Baghdad in the North and Hilla in the South was only two metres. The western part of the plain was intersected by former and current branches of the Euphrates, which generally ran from Northwest to Southeast.
The large, primary branches of the Euphrates dominated this area throughout antiquity. The drainage of these branches was determined by the micro-relief of the plain. In the Southeast, towards the current course of the Tigris, the terrain dropped three metres, only to rise again as it approached the river. As a result, all watercourses and canals drained in the same direction, and a depression southwest of Baghdad often formed a seasonal swamp lake.
For the start of settlement and irrigation, the authors assumed a period from the beginning of the 4th to the end of the 3rd millennium BC. They mentioned that there was a long drainage channel running southwest of a levee. However, they also indicated that there was waterlogging, salinization, and regular flooding. It therefore appears that the drainage channel carried excess water downstream by gravity and that a polder had not yet been made.
The second area - Old Sumer - lay in the heart of the downstream part of Mesopotamia. Here, the differences in microrelief were much greater. This area was bounded in the West by the Hillah and Hindiyah branches of the Euphrates, in the East by the Tigris, in the North by the remnants of the Shatt al-Nil, and until the beginning of the present era, in the South by vast swamps.
In the West, the discharge of two major branches and countless smaller branches of the Euphrates, combined with human activity to control the water, created an environment prone to marsh formation.
In the central part, the landscape was characterized by flat arable fields interspersed with rows of dunes consisting of loose, wind-blown soil originating from open fields and old river branches. Over time, cycles of human activity aimed at agricultural expansion, followed by increased wind erosion of the ploughed soil, had contributed to alternating periods of significant sedimentation and erosion, with associated shifts of the dunes.
In the area lay three large, centuries old levees along the Euphrates, situated at the crossroads between the present-day agricultural land and the desert - an area subject to significant wind erosion, but also to continuous use and reuse. The centuries-old levees date from the third to the first millennium BC. Hritz and Pournelle also described that the distribution of irrigation water across the river branches and canals was strictly regulated to conserve water and prevent flooding. In this regard, see also my contribution to Flevolands Geheugen on The Legislation of Hammurabi, King of Babylon.
Finally, excess water flowed away to a basin, thereby preventing soil salinization. In such gravity-based irrigation systems, so-called herringbone landscapes were found, comparable to those in the lower-lying areas of the first area.
The third area – the Sealands – lay further South, in the lowest and flattest part of the delta. Here, until the beginning of the current era, when they were systematically reclaimed, reed marshes, lakes, salt marshes, lagoons, mudflats, and salt pans predominated, where the water from Mesopotamia collected and eventually flowed into the sea.
The size and distribution of the areas in the watery patchwork changed over time. Changes depended on rainfall in the upper reaches of the rivers, the monsoons that influenced the winter and early summer rains at the entrance to the Persian Gulf, the inflow and retreat of seawater, sediment supply and deposition by the rivers, and upstream water use for irrigation.
For this area, Hritz and Pournelle assumed that around 6000 BC, towards the end of what appears to have been the first period of substantial habitation in Tell el-'Oueili, the head of the Persian Gulf extended as far as present-day Basra due to rising sea levels. The precise boundaries of the coast at that time are unclear, but it is clear that over the course of the following two millennia, at its highest level, the sea flooded a large part of the South of present-day Iraq.
In the resulting inner delta, a dynasty arose known as the Sea Peoples, as evidenced by cuneiform texts from the middle of the second millennium BC, but similar conditions likely existed from the very beginning of life in cities in this region, two millennia earlier. For instance, the great city of Uruk appears to have originated from separate, parallel settlements founded on the higher, marshy grounds in the branches of the delta, where a main branch of the Tigris-Euphrates river system, which existed at the time, flowed into vast marshes along the beginning of the Persian Gulf.
