Finish Roll Forming Gears by the Rack Die System : Improvement of Tooth Accuracy (Ist Report)

ラック形工具により自由駆動方式で高圧力角・低歯歯車を仕上げ転造する。素材歯部の転造代・歯ミゾ部とホブの関係を検討し,前加工はこのホブによった。転造代を変更してこれが歯底部の逃げミゾの有無による結果の製品精度への影響を調べた。主要な精度項目の測定結果から,ミゾ付の有利さがわかり,一定の歯車要目の場合の転造代の量がわかった。また,転造後の内径拡大量とも合せて検討し,今後の問題点(方向)を示した

Quality of caesarean delivery services and documentation in first-line referral facilities in Afghanistan: a chart review

<p>Abstract</p> <p>Background</p> <p>Increasing appropriate use and documentation of caesarean section (CS) has the potential to decrease maternal and perinatal mortality in settings with low CS rates. We analyzed data collected as part of a comprehensive needs assessment of emergency obstetric and newborn care (EmONC) facilities in Afghanistan to gain a greater understanding of the clinical indications, timeliness, and outcomes of CS deliveries.</p> <p>Methods</p> <p>Records were reviewed at 78 government health facilities expected to function as EmONC providers that were located in secure areas of the country. Information was collected on the three most recent CS deliveries in the preceding 12 months at facilities with at least one CS delivery in the preceding three months. After excluding 16 facilities with no recent CS deliveries, the sample includes 173 CS deliveries at 62 facilities.</p> <p>Results</p> <p>No CS deliveries were performed in the previous three months at 21% of facilities surveyed; all of these were lower-level facilities. Most CS deliveries (88%) were classified as emergencies, and only 12% were referrals from another facility. General anesthesia was used in 62% of cases, and spinal or epidural anesthesia in 34%. Only 28% of cases were managed with a partograph. Surgery began less than one hour after the decision for a CS delivery in just 30% of emergency cases. Among the 173 cases, 27 maternal deaths, 28 stillbirths, and 3 early neonatal deaths were documented. In cases of maternal and fetal death, the most common indications for CS delivery were placenta praevia or abruption and malpresentation. In 62% of maternal deaths, the fetus was stillborn or died shortly after birth. In 48% of stillbirths, the fetus had a normal heart rate at the last check. Information on partograph use was missing in 38% of cases, information on parity missing in 23% of cases and indications for cesareans missing in 9%.</p> <p>Conclusions</p> <p>Timely referral within and to EmONC facilities would decrease the proportion of CS deliveries that develop to emergency status. While the substantial mortality associated with CS in Afghanistan may be partly due to women coming late for obstetric care, efforts to increase the availability and utilization of CS must also focus on improving the quality of care to reduce mortality. Key goals should be encouraging use of partographs and improving decision-making and documentation around CS deliveries.</p

The Decline

Declining stage of the Abbasid Khilafa is followed meticulously until its collapse in the fall of Baghdad to the Mongols in 1258. The full sequence of events, which had resulted in this most important event to Mesopotamia is followed and the decline in agriculture in the whole of al- Sawad during this is period, is carefully described. Agriculture had formed the main contributor to the economy and strength of the Khilafa State, but it had continuously suffered neglect and destruction during this period due to negligence of the central governments of the irrigation systems and the destruction of these systems during conflicts and revolts that became dominant during the last phase of al- Khilafa State. The large spending of the late Khalifahs and the depletion of the treasury, and their dependence on foreign military troops, who were mainly Turks, to support their rule, mark the beginning. By loss of sizable revenues, this had interacted again with the Khalifahs weakness causing more revolts and anarchy by various unsatisfied groups and by the troops themselves over their unpaid salaries. The war between al-Muntasir and his brother al- Mu’tazz over the thrown following the assassination of their father al-Mutawakkil is detailed by giving full attention to the large damages it caused to irrigation canals and flooding of large areas between Baghdad and Samarra. Following this the revolt of Zanj in Southern al- Sawad and the long conflict with the Qarmatians are then outlined by reporting the reasons and describing the consequences of those important wars in details, accounting at the same time the high costs of these wars and the extent of severe damages to population centres, cultivation lands and their irrigation works. During the Buwayhids period, the Abbasid Khlilafa experienced its worst moments as the Buwayhids did not contribute much to the welfare of the people, nor could they do much to reverse the trend of decline that was progressing. As a matter of fact they had committed their biggest mistake in tearing apart the land ownership system prevailing till that time by introducing a new form of Iqta’ known as the Military Iqta’s. New methods of land and crops tax collection system were introduced and thus disrupting long established procedures that were followed since the Sassanid era and had proved their success. Conflicts and wars during the Buwayhid rule and the large-scale corruption, which are fully reported here, had undermined the central power needed for the proper management of agriculture and for the well keep of the irrigation canal systems. Finally, when the Buwayhid strength was drained they were expelled under a new rising power in the Seljuks. The Seljuks proved during this period to be not much different from the Buwayhids and their Sultans kept the real power in their hands making the Khalifah a titular head of state only. The conditions of the economy was as bad as it was before, and the people complained much over the recurrent crises of extremely high food prices during these times. Worst of all the Seljuk Sultans surpassed the Buwayhids in practicing the Iqta’ of the cultivated land by distributing qati’as not only to the military leaders as the Buwayhids did but they extend this to an unprecedented levels for the Seljuk Sultans had granted all the land to their Seljuk soldiers, their relatives and friends who were only Seljuks. To comprehend the magnitude of this; the number of the soldiers only in the time of Malik Shah who benefited from this system was forty six thousand horsemen; many more high ranking Seljuk persons were also entitled to qati’as under the same rules. With the passage of time the basic principle of this system were violated, and most of the beneficiaries succeeded in keeping the land as their own , used all sorts of abuses towards their farmers and even passed it in inheritance to their children. Some others encroached on neighboring qati’as, which belonged to others, and injustice and corruption became widespread. Negligence to repair these canals in so many cases leading to the permanent abandonment of land is also cited illustrated with many examples. In addition, many striking cases of failures of canals and their head works after large floods are fully described based on the reports given by contemporary writers. The details presented give an insight to the scale of the large fertile areas and the cities and towns that were badly affected and give evidence to the very low level that the State had reached during its last days after losing so much fertile lands and their agriculture.Validerad;2020;Nivå 1;2020-04-24 (alebob)</p

Epilogue

In more than six centuries which followed the fall of Baghdad to the hands of Hulagu and his Mongol troops in 1258 until the establishment of the modern state of Iraq in 1920. The timeline of the country cannot be described but only as a sequence of tragic events in which this once most prosperous land sank into unending bloodsheds, destruction, constant retrogression and deep poverty. Calamities such as flooding, epidemics, locusts and famines did not spare millions of its population, and to speak of Baghdad only, the 1,000,000 who used to live there in the golden days of the Abbasids dwindled to merely few thousands at the turn of the twentieth century. The early stage of this severe collapse was due to the interference of the Mongols with the irrigation systems on which the life of people had depended. Admitting that the damage that was sustained during the Buwayhids and Seljuks times left these systems in dilapidated and bad conditions, but the Mongols managed to add more destruction so that agriculture diminished to small plots of lands, which could not keep up the large population anymore and made any effort of reform nearly impossible. Borrowing from the words of Stephen Hemsley longrigg in his book “Four Centuries of Modern Iraq” he says: “Most ruinous of Holagu’s acts had been the studied destruction of the dykes and head works, whose ancient and perfect system had been the sole source of the wealth. Disordered times, and the very silting and scouring of the rivers once let loose, soon made the restoration  of control the remote, perhaps hopeless problem today still unsolved”[1].Validerad;2020;Nivå 1;2020-04-24 (alebob)</p

Sammara and its Canals

As the history of this land continues to unfold, we come to the time when the capitol of the State was moved to a new city to the north of Baghdad, which was called Samarra, and this was the opportunity taken by the Khalifahs to build new palaces and excavate new canals and open more land for cultivation. In this paper details on the building of Sammara by Khalifah al- Mu’tasim, son of Khalifah Harun al- Rashid and moving the capitol to it from Baghdad in the year 836 and remaining as such until 892 are given. One of the main reasons which led al-Muʿtaṣim to build Samarra and moving to it was the problems raised by the presence of his Turkish slave-soldiers in Baghdad and the friction they had created with the population. Al-Muʿtaṣim construction works in Samarra, the various public buildings, and numerous palaces he constructed here are described. As the city was located on the eastern bank of the Tigris, water supply could not be drawn to it by gravity since its location was higher than the river and even higher than the Katul Kisrawi canal adjoining to it from the east. Therefore, the irrigation works of al- Muʿtaṣim were concentrated on the western bank of the Tigris, which he had already connected it to the right bank by building a bridge. The main irrigation work he embarked upon was the construction of Nahr Ishaqi Canal. This old canal dated to the Partho- Sassanid era but it had to be re-excavated and remodeled since it was already filled up by sediments and abandoned. More over the canal had to be extended for a very long distance downstream to irrigate all the qati’as he had given to his top generals and courtiers to develop into cultivations and farms. These farms then produced all sorts of crops and fruits while the large date palm orchards planted here gave the best types of dates. Moreover, the canal in its downward route supplied water to the large tract of land that al- Mu’tasim had reserved for the encampment of his Maghariba troops which was called “Istablat”. Details of the barracks, housing quarters, stables and training arena of the encampment are presented in addition to the three branch canals off taking from Nahr Ishaqi, which were to irrigate also the extensive pastureland that was reserved for the 140,000 cavalry horses to graze in. The canal was then followed to its end in the other old canal called al- Dujail canal. The works of al- Mu’tasim, however, were no match to what his grandson al- Mutawakkil had done which are described. This Khalifah was determined to irrigate Samarra by gravity from the Tigris and to have plentiful water supply to the city and to his palaces and to his many artificial ponds. He embarked on a daring project by constructing a dual kariz and open channel conduit system taking water from the Tigris at a location forty kilometers north of Samarra and running for great part of its length along the Katul Kisrawi canal adapting to the hilly topography of the land. The scheme was then described following its course after crossing the Katul by an aqueduct to an earth reservoir. This reservoir was built to retain the incoming water before distributing it to the main city dual Kariz, and to the canal supplying the Dakka palace. In addition to the flood escape channel that was known as the Nahr Murayr which took off from the west side of the reservoir and passed down to the Tigris where it poured. The main city Kariz system is followed i and the details of its branching network are fully described. Such details covered the water supply to the racing courses, the Dar Khilafa palace and its unique pools intended for the Khalifah’s pleasure and the water supply to Abu Dulaf Mosque congregational mosque with its famous fountain. Having finished in the Tigris at al- Matira this stream could not irrigate the 5000 hectares of land of al- Hayr, or the wild animal reserve created by al- Mutawakkil to practice his hobby of hunting, as this land was above its course. The al- Hayr was so important to al- Mutawakkil that he excavated a new canal directly from the Katul, which commanded the whole area, called it Nahr al Nyzak and gave from its final reach a branch to another palace he built there and supplied one more of his favorite ponds adjoined to it. The construction works of al- Mutawakkil were not confined to Samarra but he extended this to build a new city 18 kilometers to the north of Samarra and called it al- Mutawakkiliyya, and here he again built new government compound, a mosque and gave qati’as to his sons, generals and may more people to build houses and palaces. He built for himself another palace and called it al Ja’fari. To supply the new city with water, he ordered the excavation of a new canal, which he called Nahr al Ja’fari. The intake of this canal was on the Tigris River some forty kilometer north of Tikrit and it followed a course parallel to the river for a considerable distance before it crossed the Katul Kisrawi by an aqueduct and then entered the city. This project proved an engineering failure as the ground, which had to be dug, was extremely hard and the work had to be stopped after spending twenty five million dirham. While some of these works may be considered as grand works, they were very costly and deprived public works such as irrigation networks from their share necessary for their maintenance and proper functioning. This extravagance coupled with political intrigues led to the assassination of al- Mutawakkil in a plot that was planned by his own son. This point marked the beginning of the decline of al- Khilafa which took some more time till it finally collapsed in 1258 fall of Baghdad on the hands of the Mongols. In addition to Samarra and its irrigation work described also the Nahr Dujail canal flowing on the western bank of the Tigris not far downstream from Samarra. Much older than Samarra itself, it was irrigating a large tract of land extending to Baghdad. In description of the course of the canal followed its western branch, which had gone out of use at the Abbasid times and also concentrated attention on the eastern branch that was known as Nahr Batatiya. It irrigated the Tusuj of Maskin before it reached the northern parts of Baghdad and branched into a dense network of watercourses that supplied al- Harbbiyyah quarter. Further details are presented of the various places and parts of this quarter that benefited from these watercourses before the full supply was exhausted. The details as given augment therefore the description of the canal networks serving Baghdad (the round city and the Karkh districts) that had originated from Nahr Isa. The Abbasid Khilafa after it had experienced its golden era began after the assassination of al- Mutawakkil, a long process of slow but steady decline due to multiplicity of reasons.Validerad;2020;Nivå 1;2020-04-24 (alebob)</p

Present Water Crises in Iraq and Its Human and Environmental Implications

Iraq is facing a serious water shortage problem now, which has not been experienced before. This is because of the reduction of flow of the Euphrates and Tigris Rivers which is due to the implementation of hydrological projects within the upstream part of the catchment and climate change. Mismanagement of water resources within Iraq made the problem graver. It is believed that serious discussion with all riparian countries to reach an agreement to share the water of the two rivers and their tributaries is desperately needed. In addition, a prudent scientific strategy should be implemented and put into practice to overcome this problem in Iraq. In addition, the key positions within the Iraqi Ministry of Water Resources should be given to people having real experience in the water resources sector to ensure discreet and prudent management of the problem.Validerad;2018;Nivå 1;2018-06-12 (andbra)</p

Babylon in a New Era : The Chaldean and Achaemenid Empires (330-612 BC)

The new rise of Babylon is reported and its domination of the old world is described; when two dynasties ruled Neo- Babylonia from 612 BC to 330 BC.  First, the Chaldeans had taken over from the Assyrians whom they had defeated and established their empire, which lasted for 77 years followed by the Achaemenid dynasty, which was to rule Babylonia for the remaining period as part of their empire. Out of the 77 years of the Chaldean period king, Nebuchadnezzar II ruled for 43 years, which were full of military achievements and construction works and organization. Apart from extending the borders of the empire, he had managed to construct large-scale hydraulic works which were intended for irrigation, navigation and even for defensive purposes. He excavated, re-excavated, and maintained four large feeder canals taking off from the Euphrates, which served the agriculture in the whole area between the Euphrates and the Tigris in the middle and lower Euphrates regions. Moreover, he was concerned with flood protection and so he constructed one large reservoir near Sippar at 60 km north of Babylon to be filled by the Euphrates excess water during floods and to be returned back to the river during low flow season in summer. His works involved river training projects, so he trained the Euphrates by digging artificial meanders to reduce the velocity of the flow and improving navigation and allow the construction of the canal intakes in a less turbulent flows. It seems also that he had diverted the river during the building of Babylon Bridge and trained the Euphrates River penetrating Babylon by constructing riverside revetments. Nebuchadnezzar II had the foresight for building extensive defensive fortifications to secure the country against possible enemy attacks from the north and adding to the walls and fortifications deep moats filled with water for higher security. This was the case with the wall he built north of Sippar. It extended over the whole distance between the two rivers, and the wall around Sippar itself. Similarly, he had dug a great moat alongside the wall of Babylon, which he supplied with water from the Euphrates. Moreover, he had introduced improvements on the four large feeder canals and the extensive canal networks that belonged to them to be used as water barriers against the advance of any enemy troops. Building temples and grand royal palaces and the Babylon Bridge took part of Nebuchadnezzar’s attention and his name was linked with the “Babylon Hanging Gardens”, one of the seven wonders of the ancient world, which he had built to please his wife. Description of the gardens according to historians is given in this book in addition to reporting the results of archeological digging of the supposed site, which can shed light on the irrigation method used to irrigate these elevated gardens. The flourishing agriculture and wealth and prosperity it had brought to Babylon during Nebuchadnezzar’s reign is described in details, and the active trading and commercial dealing it had generated is also treated. The first banking services in history related to this period, which was linked to one Jewish family known as “House of Êigibi” is described. This family continued to serve for very long time by collecting the land rents and water taxes for canals use for the government, in addition to concluding contracts and ratifying transactions for the public. As bankers, they gave farmers loans to invest in all types of agrarian operations and practiced money transfers between various cities which helped trading especially with large scale export and imports of the various crops. The Chaldeans rule of Babylon came to an end in 539 BC when Babylon fell to the Achaemenids attacks that were already established in Persia led by Cyrus II. Babylon, however, kept a special position between the various capitols of this empire due to its splendor and wealth. It served therefore as the economical capitol and the winter residence of the kings Achaemenid Empire for most of this period while its agriculture continued to generate a great portion of the empire’s revenue. The archive gave us information on the agrarian relations and the agricultural outputs in Babylonia at that period. During the Achaemenid times, as it was the case during the Chaldean times, irrigation systems in Babylonia were kept under close observation and good maintenance which kept agriculture at its best. The inevitable decline of this empire came in the end due to the rule of weak kings, conspiracies and palace intrigues, and finally the bitter defeat came on the hands of Alexander the Great who entered Babylon in 331 BC and kept it as the Jewel of his new empire.Validerad;2020;Nivå 1;2020-04-24 (alebob)</p

Mosul Dam the Full Story : Engineering Problems

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 permanentlyValiderad; 2016; Nivå 1; 20160825 (nadhir)</p

Sammara and its Canals

As the history of this land continues to unfold, we come to the time when the capitol of the State was moved to a new city to the north of Baghdad, which was called Samarra, and this was the opportunity taken by the Khalifahs to build new palaces and excavate new canals and open more land for cultivation. In this paper details on the building of Sammara by Khalifah al- Mu’tasim, son of Khalifah Harun al- Rashid and moving the capitol to it from Baghdad in the year 836 and remaining as such until 892 are given. One of the main reasons which led al-Muʿtaṣim to build Samarra and moving to it was the problems raised by the presence of his Turkish slave-soldiers in Baghdad and the friction they had created with the population. Al-Muʿtaṣim construction works in Samarra, the various public buildings, and numerous palaces he constructed here are described. As the city was located on the eastern bank of the Tigris, water supply could not be drawn to it by gravity since its location was higher than the river and even higher than the Katul Kisrawi canal adjoining to it from the east. Therefore, the irrigation works of al- Muʿtaṣim were concentrated on the western bank of the Tigris, which he had already connected it to the right bank by building a bridge. The main irrigation work he embarked upon was the construction of Nahr Ishaqi Canal. This old canal dated to the Partho- Sassanid era but it had to be re-excavated and remodeled since it was already filled up by sediments and abandoned. More over the canal had to be extended for a very long distance downstream to irrigate all the qati’as he had given to his top generals and courtiers to develop into cultivations and farms. These farms then produced all sorts of crops and fruits while the large date palm orchards planted here gave the best types of dates. Moreover, the canal in its downward route supplied water to the large tract of land that al- Mu’tasim had reserved for the encampment of his Maghariba troops which was called “Istablat”. Details of the barracks, housing quarters, stables and training arena of the encampment are presented in addition to the three branch canals off taking from Nahr Ishaqi, which were to irrigate also the extensive pastureland that was reserved for the 140,000 cavalry horses to graze in. The canal was then followed to its end in the other old canal called al- Dujail canal. The works of al- Mu’tasim, however, were no match to what his grandson al- Mutawakkil had done which are described. This Khalifah was determined to irrigate Samarra by gravity from the Tigris and to have plentiful water supply to the city and to his palaces and to his many artificial ponds. He embarked on a daring project by constructing a dual kariz and open channel conduit system taking water from the Tigris at a location forty kilometers north of Samarra and running for great part of its length along the Katul Kisrawi canal adapting to the hilly topography of the land. The scheme was then described following its course after crossing the Katul by an aqueduct to an earth reservoir. This reservoir was built to retain the incoming water before distributing it to the main city dual Kariz, and to the canal supplying the Dakka palace. In addition to the flood escape channel that was known as the Nahr Murayr which took off from the west side of the reservoir and passed down to the Tigris where it poured. The main city Kariz system is followed i and the details of its branching network are fully described. Such details covered the water supply to the racing courses, the Dar Khilafa palace and its unique pools intended for the Khalifah’s pleasure and the water supply to Abu Dulaf Mosque congregational mosque with its famous fountain. Having finished in the Tigris at al- Matira this stream could not irrigate the 5000 hectares of land of al- Hayr, or the wild animal reserve created by al- Mutawakkil to practice his hobby of hunting, as this land was above its course. The al- Hayr was so important to al- Mutawakkil that he excavated a new canal directly from the Katul, which commanded the whole area, called it Nahr al Nyzak and gave from its final reach a branch to another palace he built there and supplied one more of his favorite ponds adjoined to it. The construction works of al- Mutawakkil were not confined to Samarra but he extended this to build a new city 18 kilometers to the north of Samarra and called it al- Mutawakkiliyya, and here he again built new government compound, a mosque and gave qati’as to his sons, generals and may more people to build houses and palaces. He built for himself another palace and called it al Ja’fari. To supply the new city with water, he ordered the excavation of a new canal, which he called Nahr al Ja’fari. The intake of this canal was on the Tigris River some forty kilometer north of Tikrit and it followed a course parallel to the river for a considerable distance before it crossed the Katul Kisrawi by an aqueduct and then entered the city. This project proved an engineering failure as the ground, which had to be dug, was extremely hard and the work had to be stopped after spending twenty five million dirham. While some of these works may be considered as grand works, they were very costly and deprived public works such as irrigation networks from their share necessary for their maintenance and proper functioning. This extravagance coupled with political intrigues led to the assassination of al- Mutawakkil in a plot that was planned by his own son. This point marked the beginning of the decline of al- Khilafa which took some more time till it finally collapsed in 1258 fall of Baghdad on the hands of the Mongols. In addition to Samarra and its irrigation work described also the Nahr Dujail canal flowing on the western bank of the Tigris not far downstream from Samarra. Much older than Samarra itself, it was irrigating a large tract of land extending to Baghdad. In description of the course of the canal followed its western branch, which had gone out of use at the Abbasid times and also concentrated attention on the eastern branch that was known as Nahr Batatiya. It irrigated the Tusuj of Maskin before it reached the northern parts of Baghdad and branched into a dense network of watercourses that supplied al- Harbbiyyah quarter. Further details are presented of the various places and parts of this quarter that benefited from these watercourses before the full supply was exhausted. The details as given augment therefore the description of the canal networks serving Baghdad (the round city and the Karkh districts) that had originated from Nahr Isa. The Abbasid Khilafa after it had experienced its golden era began after the assassination of al- Mutawakkil, a long process of slow but steady decline due to multiplicity of reasons.Validerad;2020;Nivå 1;2020-04-24 (alebob)</p

The Decline

Declining stage of the Abbasid Khilafa is followed meticulously until its collapse in the fall of Baghdad to the Mongols in 1258. The full sequence of events, which had resulted in this most important event to Mesopotamia is followed and the decline in agriculture in the whole of al- Sawad during this is period, is carefully described. Agriculture had formed the main contributor to the economy and strength of the Khilafa State, but it had continuously suffered neglect and destruction during this period due to negligence of the central governments of the irrigation systems and the destruction of these systems during conflicts and revolts that became dominant during the last phase of al- Khilafa State. The large spending of the late Khalifahs and the depletion of the treasury, and their dependence on foreign military troops, who were mainly Turks, to support their rule, mark the beginning. By loss of sizable revenues, this had interacted again with the Khalifahs weakness causing more revolts and anarchy by various unsatisfied groups and by the troops themselves over their unpaid salaries. The war between al-Muntasir and his brother al- Mu’tazz over the thrown following the assassination of their father al-Mutawakkil is detailed by giving full attention to the large damages it caused to irrigation canals and flooding of large areas between Baghdad and Samarra. Following this the revolt of Zanj in Southern al- Sawad and the long conflict with the Qarmatians are then outlined by reporting the reasons and describing the consequences of those important wars in details, accounting at the same time the high costs of these wars and the extent of severe damages to population centres, cultivation lands and their irrigation works. During the Buwayhids period, the Abbasid Khlilafa experienced its worst moments as the Buwayhids did not contribute much to the welfare of the people, nor could they do much to reverse the trend of decline that was progressing. As a matter of fact they had committed their biggest mistake in tearing apart the land ownership system prevailing till that time by introducing a new form of Iqta’ known as the Military Iqta’s. New methods of land and crops tax collection system were introduced and thus disrupting long established procedures that were followed since the Sassanid era and had proved their success. Conflicts and wars during the Buwayhid rule and the large-scale corruption, which are fully reported here, had undermined the central power needed for the proper management of agriculture and for the well keep of the irrigation canal systems. Finally, when the Buwayhid strength was drained they were expelled under a new rising power in the Seljuks. The Seljuks proved during this period to be not much different from the Buwayhids and their Sultans kept the real power in their hands making the Khalifah a titular head of state only. The conditions of the economy was as bad as it was before, and the people complained much over the recurrent crises of extremely high food prices during these times. Worst of all the Seljuk Sultans surpassed the Buwayhids in practicing the Iqta’ of the cultivated land by distributing qati’as not only to the military leaders as the Buwayhids did but they extend this to an unprecedented levels for the Seljuk Sultans had granted all the land to their Seljuk soldiers, their relatives and friends who were only Seljuks. To comprehend the magnitude of this; the number of the soldiers only in the time of Malik Shah who benefited from this system was forty six thousand horsemen; many more high ranking Seljuk persons were also entitled to qati’as under the same rules. With the passage of time the basic principle of this system were violated, and most of the beneficiaries succeeded in keeping the land as their own , used all sorts of abuses towards their farmers and even passed it in inheritance to their children. Some others encroached on neighboring qati’as, which belonged to others, and injustice and corruption became widespread. Negligence to repair these canals in so many cases leading to the permanent abandonment of land is also cited illustrated with many examples. In addition, many striking cases of failures of canals and their head works after large floods are fully described based on the reports given by contemporary writers. The details presented give an insight to the scale of the large fertile areas and the cities and towns that were badly affected and give evidence to the very low level that the State had reached during its last days after losing so much fertile lands and their agriculture.Validerad;2020;Nivå 1;2020-04-24 (alebob)</p