Journal of Earth Sciences and Geotechnical Engineering, Vol. 11, No. 2, 2021, 35-160 ISSN: 1792-9040 (print version), 1792-9660 (online) https://doi.org/10.47260/jesge/1123 Scientific Press International Limited Irrigation projects in Iraq Mukhalad Abdullah1 and Nadhir Al-Ansari2 Abstract Iraq has a unique irrigation system since the early history, these systems are functioning through many irrigation projects built over `Tigris and Euphrates Rivers. Irrigation projects include several categories, which are dams, barrages, canals, drains, pumping stations, regulators, and reservoirs. There are six large dams inside Iraq, 5 are existing in Tigris basin, and one in Euphrates basin, these dams which were built since 1950’s are suffering from several issues, like foundation liquefaction, seismic effects, and others. Tharthar Lake, Habbaniyah Lake, Razzaza Lake, and Southern Marshes are also one of the main projects in Iraq to control flood and storing excess water in some. These lakes serve in protection of the main cities during large floods. There are also many barrages on Tigris and Euphrates, some of these barrages are part of Tharthar and Habbaniyah projects, while others serving the irrigation projects in Mesopotamia. On Euphrates, there are several irrigation projects, where the projects upstream Fallujah city are almost small or medium projects irrigated by pumping. Then, in the rest of Euphrates, there are Great Abu Ghraib project, Great Mussayab, Hilla- Kifil, some small projects, and Kifil-Shinafiyah projects. Also, Hilla branch which is the largest branch in Iraq from Euphrates, where this branch is irrigating several irrigation projects. On Tigris basin, there are Jazeera project irrigated by pumping from Mosul Dam, Kirkuk project that is irrigated from Lesser Zab River, and Diyala are projects. Inside Mesopotamia and over Tigris reach, there are Ishaqi project, Nahrawan project, Middle Tigris projects, Dujailah project, Dalmaj project, and Gharraf Canal projects. In the middle of Mesopotamian plain, Main Outfall Drain was completed in 1992, this grand drain are serving around 6 million donum of farmlands. Keywords: Dams, Barrages, Irrigation canals, Iraq. 1 Consultant engineer, Baghdad, Iraq. 2 Lulea University of Technology, Lulea, Sweden. Article Info: Received: October 27, 2020. Revised: November 1, 2020. Published online: November 15, 2020. 36 Abdullah and Al-Ansari 1. Introduction Since the early history, Iraq was known with irrigated agriculture, which was the trigger of civilization. The projects to regulate, store, and distribute water quantities in Tigris and Euphrates Rivers are existing centuries ago. After the establishment of new Iraq in 1921, the wheel moved again to build irrigation mega project, which extends along Iraq from north to south and from east to west. In this report information was compiled to manifest the water resources projects which include dams, barrages, regulators, pumping stations, canals, drains, reservoirs, and many others. First, dams and barrages will be demonstrated, then reviewing the irrigation main schemes on Tigris main course, Tigris Tributaries, and Euphrates main course. At the end, a review presented about Main outfall drain and other main drains in Mesopotamia. 2. Large Dams Development Board was first interested in the large dams, Doukan and Darbendhikhan Dams were first constructed during Development Board era. Later, at the second half of 1970s, the interest was coming to front again, where the second batch of dam had built, Hemrin, Haditha, and Mosul Dams. In the 1990s, Adhaim Dam was built. There are still in the agenda, the construction of Bekhme and Makhoul Dams. 2.1 Mosul Dam Studies were initiated to for the dam by Development Board through the companies (Alexander Gibbs & Partners) and (Munsel Basford and Bafrey), they prepared a study and submitted a joint report in 1953 that included the proposal of two sites near the moonlight village north of Aski Mosul, the proposals included a storage dam with a capacity of 8.7 billion cubic meters, and elevation of 320 m a.s.l. Then, the American company Harza was commissioned by Development Board to study the project and it presented the full report in 1960, Harza Company has indicated that the proposed previous sites are not appropriate geologically and proposed two new locations; the first has a capacity of 7.8 billion cubic meters at elevation of 320 m a.s.l. and the second has a capacity of 13.5 billion cubic meters and elevation of 325 m a.s.l. Soviet Company Technopromexport submitted a new study in 1962 and a proposal for a new storage dam with a capacity of 7.7 billion cubic meters at elevation 312 m a.s.l. Then, Imatran Voima Company was assigned to prepare a study for the proposed dam and it was presented in 1973, the report has been evaluated by Technopromexport and Board of Experts, they both raised notes concerning the dam and the need to intensify geological investigations. Next, the dam construction proposal presented for Hochtief Company to do it in 1974, and after the company review, the agreement did not happen due to the foundations issue of the dam. The Irrigation projects in Iraq 37 French company, Solseif, was later commissioned to conduct geological investigations and presented its findings in 1979. Finally, agreement was reached with the Swiss consultants to prepare the dam study, which was presented in 1979 (Adamo, Al-Ansari, et al. 2018; Al-Simawi, 2008). What has been manifested about studies, where many parties had been involved with an approaching results highlights clearly the sensitivity of Mosul Dam foundations, which resulted that the consulting companies and decision makers to re-examine and study the dam site several times, they convened a final conclusion that the dam underneath has gypsum formations which made a threat to the safety of the dam proposal, the alternative between the site and another of what it takes less remedies, and it will not be possible to find a site far of this negative findings. The length of the dam is 3,600 m, it is and earth fill dam with a clay core. The tallest height of the dam is 100 m and the operational level is 330 m a.s.l. The design storage is 11.11 billion cubic meters. The minimum operational level is 300 m a.s.l., below a dead storage equals to 2.95 billion cubic meters, as the live storage is 8.16 billion cubic meters. The dam has a gated spillway on the left side; the spillway maximum discharge is 7400 m3/s at the maximum flooding level of 338.5 m a.sl. The length of the spillway is 1.013 meters and the width is 50 meters. The flow energy through Flip-bucket end of the spillway which directed the flow 25o of horizon, Figure 1 Shows a general view of Mosul Dam (Adamo, Al-Ansari et al. 2018; Al-Simawi, 2008; USACE, 2003). The dam includes 4 power units of Francis turbines on the right side of the dam with a total capacity of 750 MW. On the right side also, there are 2 bottom outlets that ensure a minimum discharge of 330 m3/s at the elevation of 300 m a.sl. The dam also includes two diversion tunnels on the right side of the dam shoulder. The project includes a pumped storage hydropower station by storage and pumping, this station aims to meet the consumption during the peak of energy demand without wasting quantities of water. The water is stored in an artificial lake with a capacity of 11 million cubic meters constructed above Taira Hill to the right of the dam, where this plant generates 200 megawatts. There is also within the body of the dam the outlet of the South Jazeera irrigation project, which has not been completed yet, and there is a proposed hydropower station in the outlet route (Adamo, Al-Ansari, et al. 2018; Al-Simawi 2008; USACE 2003). 38 Abdullah and Al-Ansari Figure 1: General view of Mosul Dam (Edited by Author). (“Trevi Group Website” n.d.). Mosul Dam includes as fuse-plug dam on the left side of the main dam, grouting tunnels, electric transformers, piezometers, as well as infrastructure for control, management, grouting and other services. Beneath the main dam, the grouting blanket had been implemented with 20 lines and depths of (25-10m). Further; the curtain grouting were implemented which consists 5 lines, three of them are vertical, and the two on both sides has inclination of 6o, the curtain grouting varies in depth and reaching up to 150 m.(Kelley et al. 2007). Downstream of the main dam and at a distance of 9 km, the regulation dam was built on Tigris stream to control the high discharges from power plants and ensure a minimum discharge 330 m3/s. This dam was implemented by Austrian company Allen Union. The length of the regulation dam is 381 m and the height is 20 m; it is an earth fill dam with storage capacity of 21 million cubic meters. The dam includes tunnels, bottom outlets, spillway and power station that have 4 units of Kaplan turbines with a capacity of 60 MW.(Adamo, Al-Ansari, et al. 2018; Al-Simawi, 2008; USACE, 2003). Refer to Figure 2, The Regulation Dam, Mosul Dam project. Irrigation projects in Iraq 39 Figure 2: General view of the Regulation Dam, Mosul Dam project (MoWR n.d.). After the opening of Mosul Dam in 1986, the leaks began to appear from the downstream of the dam body at rates higher than the expected rates. Measurement data for sensors in the dam were periodically discussed with Board of Experts. As a result, they decided that the dam administration to continue the grouting during the service life of the dam.