Mosul Dam Full Story: What If The Dam Fails

Worries concerning the possibility of the dam failure due to the seepages under the foundation of Mosul Dam during its construction and operation phases enhanced the application of several dam failure models on Mosul Dam case. All the applied models gave similar results. It was noticed through the models that the wave in case of the dam failure will have a height of 54m and the discharge will be of the order of 551000 m3/sec. This wave will reach the capital city of Iraq “Baghdad” after about 38 hours. The discharge of the River Tigris at Baghdad will be 46000m3/sec and the height of the wave will reach 4m. The propagation of the wave along this distance will cause a catastrophe. About 500000 civilians will die in addition to the unbelievable damage that will be caused to the infrastructure of the country.

Mosul Dam is multipurpose earth fill dam. It is 3.4km long, 113m in height and its storage capacity reaches 11.11 km 3 of which 2.95 km 3 is dead storage. The dam is located on the River Tigris in the northern part of Iraq about 60 km in north west Mosul city. The dam was built on highly karstified alternating beds of gypsum, marl and limestone. The dam was operating in 1986 and since then, seepage problems started due to the solubility of the gypsum beds, presence of karstification and the effect of the local groundwater aquifer. Insensitive grouting program was put to stop the seepage and ensure the stability of the dam but it did not stop. The situation became worse in 2014 when ISIS occupied the dam area and grouting operations which were halted. Recent evaluation of the conditions indicates that the dam is in its worst conditions. The failure models of the dam indicate that 6 million people will be affected , and 7202 km 2 of land will be inundated. To stop this catastrophe, grouting operations should be continued intensively to elongate the span life of the dam. Water level within its reservoir should be kept at a very low level to minimize the damages in case of dam failure. As a permanent solution, another dam should be built downstream Mosul Dam so that it can take the wave of Mosul Dam in case of its failure.

Mağallaẗ Tikrīt li-l-ʻulūm al-handasiyyaẗ/Tikrit journal of engineering sciences, 2024

In this study, a program was built to simulate the sudden and complete collapse of the Mosul and Badush Dams behavior towards this collapse and predict the level at which the water will balance in the two dams after the collapse, compared to different levels at the Mosul Dam before the collapse. Two mathematical models were built as inputs to this program. The first predicted the water level in the Mosul Dam reservoir in terms of its storage volume before the collapse, and the second predicted the water level in the Badush reservoir after the collapse, according to the level in the Mosul reservoir before the collapse. For each collapse scenario, the program was organized according to sequential steps summarized assuming the water level in the Badush Dam reservoir when the level stabilizes, and from it determining the water volume in Badush reservoir based on the geometric analysis of the reservoir, then the volume of water transferred from Mosul reservoir to Badush reservoir, and thus the volume of water inside Mosul reservoir before the collapse. From the first mathematical model, the level of the Mosul Dam reservoir was determined before the collapse. The second mathematical model determined the level of the Badush Dam reservoir after the collapse. The results showed that the program has high flexibility in predicting what will happen in the Badush Dam reservoir after the collapse based on the water level in the Mosul Dam reservoir before it collapses and that the limits of the program's work extend from the minimum to the maximum level in Mosul Dam at which the failure can occur. Also, the storage volume in Mosul Dam will be distributed to the two reservoirs after the failure until the level stabilizes. Badush Dam, at a level of 330.4 m (a.s.l), can expand the maximum flood wave resulting from the total and sudden collapse of Mosul Dam at its maximum level of 333 m (a.s.l).

2021

Many of Iraqi's high-hazard dams lack an Emergency Action Plan, which should include a flood inundation map to show which downstream areas would be flooded if the dams were to fail. This article presents the results of the simulation of a hypothetical 2D dam break for the 58 m high Khassa Chai dam in Kirkuk, Iraq, using HEC-RAS 2D 5.0.7 software. The Khassa Chai dam is situated 7.4 kilometers north of Kirkuk. The simulations revealed that the dam-break flood will affect eight major bridges and the majority of Kirkuk city's metropolitan neighborhoods. Within an hour, the floodwaters will reach the city's center. The flood hazard map revealed that if the Khassa Chai dam fails, many people, vehicles, and structures will be at danger. The findings of this paper can be used to identify evacuation routes and refuge sites as well as build suitable warning systems in order to limit the risk for fatalities if the Khassa Chai dam fails. Moreover, as the effect of modelling bridges...

Mosul Dam is an earth fill dam located on the Tigris River in North Western part of Iraq. It is 113 m in height, 3.4 km in length, 10 m wide in its crest and has a storage capacity of 11.11 billion cubic meters. It is, constructed on be-drocks which consist of gypsum beds alternated with marl and limestone, in cyclic nature. The thickness of the gypsum beds attains 18 m; they are intensely karstified even in foundation rocks. This has created number of problems during construction, impounding and operation of the dam. Construction work in Mosul Dam started on January 25 th , 1981 and started operating on 24 th July, 1986. After impounding in 1986, seepage locations were recognized. The cause of seepage is mainly due to: 1) The karsts prevailing in the dam site and in the reservoir area. 2) The existence of gypsum/anhydrite rock formations in the dam foundation alternating with soft marl layers and weathered and cavernous limestone beddings. 3) The presence of an extensive ground water aquifer called Wadi Malleh aquifer, which affects considerably the ground water regime in the right bank. The dissolution intensity of the gypsum/anhydrite ranged from 42 to 80 t/day which was followed by a noticeable increase in the permeability and leakages through the foundation. Inspection of the dam situation in 2014 and 2015 indicates that the dam is in a state of extreme unprecedentedly high relative risk. In this work, possible solutions to the problem are to be discussed. It is believed that grouting operations will elongate the span life of the dam but do not solve the problem. Building another dam downstream Mosul Dam will be the best protective measures due to the possible failure of Mosul Dam, to secure the safety of the downstream area and its' population.

Water Science and Technology

The aim of this study is to analyze the effects of a possible dam failure under various scenarios and to generate a flood hazard map for two consecutive dams located in a study area with a dense-residential region and a heavy-traffic highway. Two consecutive dams consist of Elmalı 2, a concrete-buttress dam and Elmalı 1, an earth-fill gravity dam in the upstream and downstream, respectively. Hydrologic Engineering Center-River Analysis System (HEC-RAS) was used to develop a dam failure model. Dam failure scenarios were examined regarding three main criteria: the Breach Formation Time (BFT), the Number of Failed Buttresses (NFB) of Elmalı 2, and the Reservoir Volume Ratio (RVR) of Elmalı 1. Accordingly, flood peak depth (Hp), peak flow rate (Qp), peak velocity (vp), and time to reach the peak (tp) are discussed. The results showed that BFT and NFB of Elmalı 2 were highly effective on these values, whereas RVR of Elmalı 1 had no significant effect. Moreover, the total area affected by...

Mosul Dam is the second biggest dam in the Middle East due to the capacity of its reservoir. Since the operation of this dam in 1986, it is suffering from seepage problems in the foundation of the dam due to the dissolution of gypsum and anhydrite layers under the foundation. This phenomenon has raised concern about the safety of the dam. Studies done during the recent years showed that grouting works can only be considered as a temporary solution at its best. It is clear now that while grouting must be continued search for long term solution must be sought if dam failure consequences are to be avoided. This must be done as soon as possible as the dam is showing more and more signs of weakness. It is further considered that the suggestions and recommendations forwarded by the team of Lulea University of Technology and the Panel of Experts in the Stockholm Workshop 24-25 May, 2016 give the most practical and suitable solutions for this problem.

Engineering, 2021

Mosul Dam is located on the River Tigris about 60 km northwest Mosul in Iraq. It is the biggest dam where its storage capacity reaches 11.11 billion cubic meters at normal operational level (330 m. above sea level). The dam was constructed on alternating beds of karistified limestone, gypsum and marl. This dam suffered from water seepage under its foundation since its operation in 1986. Grouting operations were implemented since that time to overcome this problem. This seepage is believed to be due to dissolution of gypsum beds under the foundation, which was not carefully considered by the designers. It was recommended by the international board of experts that the water level should be kept at or below 319 m.a.s.l. to minimize damages in case of the failure of the dam. ISIS occupied the dam site on 8 August 2014 and it was seized back from the hands of ISIS on the 16th of the same month. They did plenty of damage despite the short period they occupied the area. After that, the Iraqi Ministry of Water Resources rebuilt the damaged parts and used new grouting and maintenance program. Now, the dam looks very safe at 319 m water level at its reservoir. In addition, the impounding was raised 325 m.a.s.l. for few days and nothing abnormal was noticed.

The idea of building of Mosul Dam project started in 1950 and it was referred to as Aski Mosul Dam. Since that time, number of companies worked on the site selection and design of the dam. All the above companies suggested that the dam should be Earth-fill type with compressed clay core but there were different views about the exact location of the dam, spillway and electricity generating station. Grouting was suggested to be performed under the dam, spillway and the electricity generating station. In addition, they suggested that detailed geological investigation should be performed before any construction activities. In 1978, the Swiss Consultants Consortium was asked to be the consultants for Mosul Dam project. The consultants suggested that the operational water level at the dam to be 330 m (a.s.l.) while the flood and normal water levels to be 338 and 335 m (a.s.l.), respectively. The work started on 25th January, 1981 and finished 24th July, 1986. The foundation of the dam is built on alternating beds of limestone and gysum. Seepages due to the dissolution of gypsum were noticed and after impounding in 1986, new seepage locations were recognized. Grouting operations continued and various studies were conducted to find suitable grout or technique to overcome this problem. The seepage due to the dissolution of gypsum and anhydrite beds raised a big concern about the safety of the dam and its possible failure. It is believed that grouting will not solve this problem permanently.

During and after the construction of Mosul Dam, in Iraq, all the studies expressed a clear concern on the fact that the region of the dam suffers from extensive presence of soluble rock formations that might undermine the safety of the dam with its large reservoir. Most of the studies dealt with foundation treatment and safety hazards due to the dissolution of gypsum and anhydrite. To overcome the problem, grouting operations were performed. The seepage of water continued and this highlighted the possibility of the dam failure. Different grouting techniques and methods were suggested but the results were the same. Finally, it was decided to limit the maximum operation water level to EL. 319 m (a.s.l.) instead of EL.330 m (a.s.l.). This recommendation has remained in force up to now with the loss of sizable storage of irrigation water and power potential