Climatic Dynamics in the Marshes of Iraq

Zaid Hakim Jiyad
Under the supervision of Lect. Dr. Ali Khazal Jiyad

Iraq consists mainly of a flat, low-lying plain that rises gradually to the southwestern plateau, which is about 1,000 meters high, and the northeastern Zagros Mountains, which reach 3,000 meters high. The elevations on the Mesopotamian plain are almost amorphous, and range from a few meters below sea level to about 400 meters above.
The main water source for the marshes is the Tigris and Euphrates rivers, with several major tributaries flowing from Iran towards the Tigris and Hawizeh. From the upper Mesopotamian plain to the Gulf, the rivers meander slowly. The lack of flow velocity causes the rivers to silt up, forming layers and banks above the level of the plain. This makes the rivers susceptible to seasonal overflow and erratic change of course. Throughout history, the rivers have branched and changed their courses on numerous occasions. Some of the deeper parts of the marshes (lakes) are thought to have been former riverbeds that were isolated as the rivers changed their courses upstream.

The generally low slope of the plain drops further. The Tigris and Euphrates divide into several branches and form the inner delta. The branches, in turn, divide into smaller branches that branch off and change their course. The dams are smaller and lower in the upper Mesopotamian plain, and groundwater is closer to the surface, with the depressions between the channels becoming swamps.

Passing through the delta, the water flows into areas of marshes and lakes, where the land is flat. At this point, groundwater meets surface water and the groundwater erupts to form ponds.

The core of the marshes is centered around the confluence of the Tigris and Euphrates. They are usually divided into three main areas: the Hammar Marshes to the south of the Euphrates; the Central Marshes (Qurna) between the Tigris and Euphrates; and the Hawizeh Marshes to the east of the Tigris.
Historically, the marshes formed a series of roughly interconnected marsh and lake basins that flowed into each other. During periods of high flooding, large areas of desert were submerged. As a result, some previously separate marsh units merged together, forming larger wetland basins. The wetland basins themselves were composed of a mosaic of permanent and seasonal marshes, shallow and deep lakes, and mudflats that were regularly flooded during periods of high water. Also downstream, the Tigris and Euphrates rivers converge to form the Shatt al-Arab River, which flows into the Persian Gulf and is thus influenced by tides.