Karstification Effect on the Stability of Mosul Dam and Its Assessment, North Iraq

Mosul Dam is located on the Tigris river, 50 Km NW of Mosul;it is 113 m in height, 3.4 Km in length, 10 m wide in its crest and has a storage capacity of 11.1 billion cubic meters. It is an earth fill dam, constructed on bedrocks of Fat’ha Formation, which consists of gypsum beds alternated with marl and limestone, in cyclic nature. The thickness of gypsum beds attains 18 m;they are intensely karstified even in foundation rocks. Therefore, continuous grouting Programme was planned during construction, which was completed in June 1984, with planned operation age of 80 years. Due to insufficient grouting in the foundation, during last years of the last century, the Karstification was enlarged in size and quantity, causing serious problems to the stability of the dam. Since late eighties of the last century, the status of the dam and its probable collapse has caused a panic to the people of Mosul city and near surroundings. Therefore, many attempts were carried out for assessment of the dam;all of them concluded that the Karstification is the main problem and recommended continuous grouting, using modern techniques. In addition, the authorities started to build another “Badush Dam” south of Mosul Dam so that it can stop the first wave if Mosul Dam if collapsed. All geophysical and geological work executed on the dam site;it concluded that the existence of many weaknesses zones, faults and large karstified areas, in different parts of the dam site.

Sand and dust storm events in Iraq

Iraq is one of the most affected countries in the Middle East concerning the occurrences of sand and dust storms. The frequency of the occurrence has increased drastically in the last decade and it is increasing continuously. The events of sand and dust storms are either regional or local. The former, however, is more frequent than the latter. The regional event, generally extends outside the Iraqi territory, into different directions, but usually covers part of Syria, crossing the Iraqi territory towards Kuwait and Saudi Arabia, and/or towards the Arabian Gulf, and less frequently extends to Iran. The main causes in the development of sand and dust storms, in Iraq are discussed. The causes are also either regional or local. The former, however, causes more economic losses and harsh effect on the human’s health, as compared with the latter. One of the main reasons behind the development of sand and dust storms is the climatic changes within the region, especially the drastic decrease in the annual rate of rain fall, besides environmental changes, such as drying of the marshes, land degradation, and desertification. From the local causes, the most effective reason is the haphazard driving and military operations, especially in the Iraqi Southern Desert. Prudent management of water resources by using non-conventional resources and adapting suitable irrigation methods can greatly help to overcome this phenomenon and minimize the number of dust storm.

Origin of Some Transversal Linear Features of NE-SW Trend in Iraq, and Their Geological Characters

Iraq is located at the extreme northeastern part of the Arabian Plate, which is in collision with the Eurasian Plate. This collision is still onward, and has caused alignment of the evolved structures in NW-SE trend, mainly, especially in the northern, northeastern and eastern sides of Iraq. However, many transversal linear features of NE-SW trend, represented by rivers, streams, valleys, playas, anticlines and offsets are developed, in parallel trend to the main compressional forces created by the aforementioned collision. Many examples from different parts of Iraq confirm the mechanism of their formation through the geological, geomorphological, tectonics and structural aspects. Although the existing linear features are tens of kilometers in length, but almost no surface displacements were reported, except very few, in some parts of Iraq. The given examples are selected to be the most obvious, when geophysical data are available, the surface and subsurface geology of the involved area is correlated to deduce whether the surface expression coincides with the subsurface or otherwise. A brief tectonic history is also given.

Mosul Dam: Geology and Safety Concerns

Mosul Dam is an earth fill dam located on the River Tigris northern part of Iraq. The capacity of its reservoir is 11.11 billion cubic meters which makes it the fourth biggest dam in the Middle East. From geological perspective, the dam is located on double plunging anticlines. The rocks of the site are mainly composed of highly jointed and karistified alternating beds of limestones, gysum and marls, since the impoundment of the reservoir seepage of water was recognized under the foundation of the dam. To stop or minimize the seepage, intensive grouting operations were conducted. Recent investigations and evaluation of the conditions of the dam indicate that it is in a critical situation. In this paper, consequences of the dam failure are discussed and possible solutions are given.

Meandering of Tributaries of the Tigris River Due to Mass Movements within Iraq

Tigris and Euphrates are the main rivers in Iraq. The former has 5 main tributaries while the latter has no tributaries within Iraq. All these rivers exhibit meandering and/or shifting of their courses due to many reasons;such as mass movements and alluvial fan's development. The meandering and shifting of river courses due to mass movements is dealt with in this study. Many examples are given from different parts of Iraq within different rivers and streams. In each case, the geology of the involved area is described;the reasons of the shifting and/or meandering of the river course are given. GIS technique was used to determine the coverage of the involved area. Landsat, Google Earth and DEM images were used to indicate the suffered areas from shifting and meandering of the rivers and streams. When possible, age of the shifting and/or meandering of the river and stream courses was estimated;using exposure age determination;mainly depending on the presence of river terraces, erosional forms, vegetation cover and the maturity of the involved area. Some of the given examples of shifting of river courses were found to be still active;others are inactive. In many cases, indications for very large mass movement phenomena were seen. Moreover, some of the large involved areas are highly populated, others includes few houses and/ or farms. The majority of the meanders are developed due to mass movement phenomena;others are caused by alluvial fans and/or tectonic features, lime plunging of anticlines.

Al-Batin Alluvial Fan, Southern Iraq

Al-Batin alluvial fan is one of the largest alluvial fans in Iraq, especially in the Iraqi Southern Desert. Its eastern and southern limits form parts of the Iraqi-Kuwait international borders. The fan is deposited by Wadi Al-Batin, the last apex being on the southern limits of the main wide depression formed by the active Abu Jir-Euphrates Fault Zone. The main trend of the fan is almost SW-NE. The length and the maximum width of the fan are 110.192 Km and 119.1 Km, respectively, whereas the slope along its length is 0.7°. The fan is covered by gypcrete sheet with thickness varying from (0.5 - 1.5) m. Four stages were recognized within the fan, which is dated to be Pleistocene in age. The four stages are marked by clear height differences. The deposition of the alluvial fan is highly affected by the activity of the active Abu Jir-Euphrates Fault Zone, which is represented on the surface as a wide shallow depression in which the fan is laid down by Wadi Al-Batin. The continuous deposition of the fan has affected the course of the Euphrates Formation within Hammar Marsh and also the course of Khor Al-Zubair in its upper reaches south of Al-Qurna, where the Euphrates and Tigris rivers merge together. Also there is a trace of ancient distributary of the Euphrates River that was flowing directly to the Arabian Gulf, through an estuary, which is abandoned and does not exist anymore.

Fuzzy Logic Implementation of Vulnerability Assessment in a Coastal Aquifer of Northern Sicily

Aquifers can be defined as complex ecological systems. Their description is closely influenced by geometrical and geological parameters, which portray the hydrogeological behaviour of underground systems. This paper reports a contribution to assessing groundwater contamination risk in a particular Sicily sector, where deterministic approaches have methodically assessed and mapped vulnerability and quality of groundwater. In detail, in the coastal area of Acquedolci (Northern Sicily), already intensely surveyed in the frame of interdisciplinary projects on geological risk, implementing models and systems have been experimented, also considering fuzzy logic. Cartography issues are here presented and compared, with particular regard to the effect of stochastic hydrogeological elements (i.e. “depth to water”), locally characterized by variability for simultaneous climate, overdraft, irrigation and sea encroachment. The authors show how fuzzy logic, applied to vulnerability settings, contributes to a better comprehension of the passive scenery offered by aquifers in Acquedolci Sicily area.

Vanadium mineralization at Los Chihuidos sediment-hosted Cu-V deposit,Neuquén Basin,Argentina:An approach to vanadium ore forming processes

Vanadium mineralization at Los Chihuidos deposit of the Neuquén Basin is linked to the development of a redox front system related to the inflow of hydrocarbons into the red sandstone of the Huincul Formation.Interaction of hydrocarbons with oxidized red beds and connate water generated redox reactions where hematite was dissolved due to iron reduction resulting in the discoloration of the red strata.At the contact between oxidized red sandstone and reduced white sandstone,precipitation of specific mineral phases resulted in the V ore with minor amounts of Cu.With the implementation of the redox interface,abundant V-montmorillonite and V-hematite precipitated at the more oxidizing conditions and Cu-V-corrensite-type at the more reducing conditions of the redox front.As the redox front advanced with fluids constantly migrating into the reservoir,more reducing conditions were stablished,promoting chloritization and minor illitization with V-Cu incorporation and continuous upgrading of the ore.Main ore mineralogy consists of clay minerals including V-bearing montmorillonite,Cu-V-corrensite-type,V-di-trioctahedral chlorite and Cu-tri-trioctahedral chlorite with minor V-illite-smectite mixed-layer minerals and associated secondary V-hematite.Chloritization over illitization was favored due to high amounts of Fe and Mg in detrital clasts and in connate fluids and by low K availability related to low amounts of detrital K-feldspar.The spatial transition of V and/or Cu bearing clay minerals observed through the mineralized redox front at Los Chihuidos deposit(kaolinite→smectite→illite/smectite→corrensite-type→di-trioctahedral-chlorite→tri-trioctahedral-chlorite)and the related variation of V-Cu concentrations in bulk rock are indicative of increasing pH and decreasing Eh of resident solutions from red to white sandstones during the hypogene mineralization process.Late influx of Cu-rich oxidized basinal brines precipitated main copper ore with Cu-sulfides in the white sandstone up to the contact with the redox front in contact with hydrocarbons.During uplift and exhumation,percolation of meteoric water promoted remobilization of V and Cu and the precipitation of oxidized V-Cu ore.