Marginal Column

New hydraulics for civil engineering site in Iraq


November 2015


In Iraq Bosch Rexroth has modernized a complex hydraulic system, which – in a combination of dam, lock and a rotating bridge – protects vegetation against seawater and makes inland transportation of goods possible.

Iraq’s interior is among the hottest areas in the world. Temperatures up to 51 degrees Celsius in the summer are by no means a rarity and one can wait in vain for rain between June and September. Without the water of the Euphrates and Tigris Rivers, no vegetation would survive. The Canal section Shatt al Basrah begins at the confluence of these two rivers and is used to irrigate an area of the desert not reached by the course of the river. In the high summer, where low water level prevails, there is a hazard that seawater from the Persian Gulf could infiltrate into the canal and damage plants. To prevent this, and as early as 1977, a system comprising a dam, lock and a rotating bridge was built just before the outlet of the canal into the Persian Gulf. Rexroth delivered the hydraulic equipment used here. Five hydraulic driven gates regulate and back up the sweet water here, until it at least reaches the height of the seawater. Thus it keeps the seawater from entering the canal. Once the sweet water has been backed up sufficiently, the gates are opened and the water can flow into the Gulf.

The steel hydraulic structure does, however, fulfill yet another function. Two hydraulically driven radial gates, working in cooperation, create a ship lock. In conjunction with a hydraulically rotated bridge it becomes possible for marine traffic to enter the canal.

Renewal with great forces

The system was damaged as a result of conflicts in Iraq. Bosch Rexroth in Romania, in July 2014, was able to land the contract for the system’s rehabilitation. Support was rendered by the Civil Engineering Project Department in Germany, which took care of manufacturing the hydraulic equipment – seven cylinders and nine hydraulic power units. A special challenge was encountered during rehabilitation work. The system should work with larger forces than the original equipment did. The experts at Bosch Rexroth developed cylinders for this purpose. They were able to withstand greater loads but still fit in the existing steel structure. This necessitated extensive changes in the engineering of the cylinders. In addition, they fitted the cylinders with a new meas-urement system, able to determine the height of the regulating gates and the bridge at any given position, right down to the millimeter. The rehabilitation of the system is to be concluded by the end of this year.

How the ship lock works

How the ship lock works

If a ship wants to travel from the higher, freshwater body to the lower saltwater level, the left gate is first opened, letting freshwater flow into the chamber, equalizing the water levels (1). Once the correct level is reached, the gate is lowered completely, allowing the ship to travel into the chamber (2). Now the right-hand gate is opened slightly, so that water can flow out of the chamber, equalizing the water level with the seawater level (3). Once the levels are equal, the gate opens completely and the ship can depart in the direction of the Persian Gulf.