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  • 1.
    Al-Ansari, Nadhir
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Ammar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Suhail, Qusay
    Department of Earth Sciences, College of Science, Baghdad University.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Flow of River Tigris and its Effect on the Bed Sediment within Baghdad, Iraq Open Engineering2015Ingår i: Open Engineering (Formerly Central European J. of Engineering), ISSN 2391-5439, Vol. 5, s. 465-477Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    River Tigris is a major river in Iraq. Sediment at the bed of the river within a reach of about 18 km starting at the center of Baghdad upstream was investigated. Sixty five cross sections were surveyed and 46 sediment samples were collected and analyzed. It was noticed that fine sand was dominating the bed (90.74%). The average median size within the reach was 2.49 phi (0.177mm) while the mean size was 2.58 phi (0.16mm). In addition the sediments were moderately sorted, fine skewed and leptokurtic. The size of the bed sediment relatively decreased compared to older investigations due to the construction of Adhaim dam on tributary which used to be the main sediment supplier to the Tigris River before entering Baghdad. Furthermore, the discharge of the Tigris River for the period 1983-2013 (715m3/s) had decreased by about 40% and 30% since 1983 compared with the period 1931-1956 (1208 m3/s) and 1956-1980 (1015 m3/s ) respectively. This had decreased the capacity and competence of the river. The bed elevation had increased compared to previous surveys. It was noticed that dredging operations and obstacles (e.g. fallen bridges and islands) disturbed the flow of the river and sediment characteristics in several sites.

  • 2.
    Al-Ansari, Nadhir
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Ammar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Iraq Water Resources Planning: Perspectives and Prognoses2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Iraq is located in the Middle East. It covers an areaof 433,970 square kilometres populated by about 32 millioninhabitants. Iraq greatly relies in its water resources on the Tigrisand Euphrates Rivers. Recently, Iraq is suffering from watershortage problems. This is due to external and internal factors. Theformer includes global warming and water resources policies ofneighbouring countries while the latter includes mismanagement ofits water resources.The supply and demand are predicted to be 43 and 66.8 BillionCubic Meters (BCM) respectively in 2015, while in 2025 it will be17.61 and 77 BCM respectively. In addition, future predictionsuggests that Tigris and Euphrates Rivers will be completely dry in2040.To overcome this problem, prudent water management policiesare to be adopted. This includes Strategic Water ManagementVision, development of irrigation techniques, reduction of waterlosses, use of non-conventional water resources and research anddevelopment planning.

  • 3.
    Al-Ansari, Nadhir
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Ammar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Present conditions and future challenges of water resources problems in Iraq2014Ingår i: Journal of Water Resource and Protection, ISSN 1945-3094, E-ISSN 1945-3108, Vol. 6, nr 12, s. 1066-1098Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iraq is part of the Middle East and North Africa (MENA region). It greatly relies in its water re-sources on the Tigris and Euphrates Rivers. Iraq was considered rich in its water resources till 1970s. After that problems due to water scarcity aroused. Recently, it is expected that water shortage problems will be more serious. The supply and demand are predicted to be 43 and 66.8 Billion Cubic Meters (BCM) respectively in 2015, while in 2025 it will be 17.61 and 77BCM respec-tively. In addition, future prediction suggests that Tigris and Euphrates Rivers will be completely dry in 2040.To overcome this problem, prudent water management plan is to be adopted. It should include Strategic Water Management Vision, development of irrigation techniques, reduction of water losses, use of non-conventional water resources and research and development planning.

  • 4.
    Al-Ansari, Nadhir
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Ammar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Restoring the Garden of Eden, Iraq2012Ingår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, nr 1, s. 53-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Iraqi marsh lands, which are known as the Garden of Eden, cover an area about 15-20 103. km2 in the lower part of the Mesopotamian basin where the Tigris and Euphrates Rivers flow. The area had played a prominent part in the history of man kind and was inhabited since the dawn of civilization. The area was considered among the largest wetlands in the world and the greatest in west Asia. Saddam regime began to drain the marsh lands for military and political reasons. Accordingly, at 2000 less than 10% of the marshes remained. The consequences were that most of the marsh dwellers left their places and some animals and plants are eradicated now. After the fall of Saddam regime in 2003, the process of restoration and rehabilitation of Iraqi marshes started. There are number of difficulties encountered in the process. Some of them are land use changes, climatic variations and changes, soil and water salinity as well as ecological fragmentation where many species were affected as well as the marsh dwellers.In this research we would like to explore the possibilities of restoring the Iraqi marshes. It is believed that 70- 75% of the original areas of the marshes can be restored. This implies that 13 km3 water should be available to achieve this goal keeping the water quality as it is. To evaluate the water quality in the marshes, 154 samples were collected at 48 stations during summer, spring and winter. All the results indicate that the water quality was bad. To improve the water quality, then 18.86 km3 of water is required. This requires plenty of efforts and international cooperation to overcome the existing obstacles.

  • 5.
    Ali, Ammar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Three Dimensional Hydro-Morphological Modeling of Tigris River2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The River Tigris is a major river in Iraq. It divides Baghdad, the capital of Iraq, in two parts. The reach of the river within Baghdad is about 60 km long. The climate change within the region and the construction of hydraulic structures upstream of Baghdad has reduced the water discharge of the river by 44%. Despite the fact that huge volumes of sediment have been trapped in the constructed headwater reservoirs, substantial changes have occurred in the topography of the Tigris River within Baghdad City and the number of depositions is increasing. The debris of the destroyed bridges from the wars of 1991 and 2003 and their subsequent reconstruction have contributed to the development of these depositions. As a consequence, the ability of the river to carry the peak flood waters has been reduced. This has led to a potential increase of flooding in parts of the city. To predict the maximum flood capacity for the river, the bathymetric survey that was conducted for 50 km of the Tigris River by the Ministry of Water Resources in 2008 has been used with the one-dimensional flow model “HEC-RAS”. Calibration of the model was carried out using field measurements for water levels along the last 15 km of the reach, and the water level observations at the Sarai Baghdad gauging station for the last 10 years were used to validate the model. The model showed a significant reduction in the river’s capacity compared with what the river had carried during the floods of 1971 and 1988. This result agrees with previous surveys conducted on the same reach indicating that the ability of the river to convey high water has decreased. To overcome this problem, dredging operations started along most of the Tigris River inside Baghdad City to remove many islands and side bars, as well as cleaning water intakes. An examination for the dredging plan currently in progress and two additional proposed plans was conducted using the ‘HEC-RAS’ model for the 50 km long river reach to investigate whether the designed flooding capacity of the river can be recovered and how much it can be improved. Comparing the historical records of water level and discharge for the last three decades, some improvement of flood capacity was achieved. Cautions about the water intakes should be considered to maintain their functionalities with the expected drop in water levels due to dredging operations. Bathymetric and land surveys were conducted for the northern Tigris River reach (18 km length) in Baghdad, producing 180 cross sections. A riverbed topography map was established from these cross sections. Sediment transport rates and bed composition were investigated by collecting three different types of sediment samples at the quartiles of 16 cross sections along this reach. The Helley-Smith sampler was used to collect 288 bedload samples, a suction pump was used to collect 212 suspended load samples from different depths. The Van Veen grab was used to collect 46 bed material samples. The velocity profiles and the water discharges were measured using ADCP at the sampling sections. Bed sediment compositions were investigated by analysing the collected bed material samples. It was noticed that fine sand dominated the riverbed (90.74%). The average median size within the reach was 2.49 phi (0.177mm) whilst the mean size was 2.58 phi (0.16mm). In addition, the sediments were moderately sorted, fine skewed and leptokurtic. The size of the bed sediment relatively decreased compared to older investigations due to the decrease of the competence of the river. The bed elevation had increased compared to previous surveys. It was noticed that dredging operations and obstacles (e.g. fallen bridges and islands) disturbed the flow of the river and the sediment characteristics in several sites. Bedload rates were computed using the weights of the collected bedload samples. The spatial distribution of sampling cross sections took into consideration the variance of river topography where 7 meanders, 2 islands and several bank depositions characterize the geometry of the river reach. Twenty bedload predictors were applied to the same reach. The annual transported quantities of the bedload were estimated to be 36 and 50 thousand tons in 2009 and 2013 respectively. The total load discharge rate in the northern reach of the Tigris River was computed using the sediment concentrations of the collected suspended load samples after adding the bedload rate at each of the sampling cross sections. The results indicated that the suspended load is the dominant mode in the total load with a minimum percentage of 93.5%. The total load ranged from 29.1 to 190.3 kg/s. A total load rating curve of the power function was established. The associated errors from using the proposed rating curve are within reassuring levels and less than the errors produced from most of the other twenty-two total load formulas, which were applied to the same reach. The scattering of the results from the other formulas can be attributed to the spatial variance in the topography of the riverbed. According to the final results obtained, it is recommended to use the proposed procedure for establishing a spatial total load rating curve to estimate sediment rates for morphologically complicated rivers. The annual transported quantities of the total load were estimated at 2.47 and 4.23 million tons for 2009 and 2013 respectively. The three-dimensional morphodynamic model (Simulation of Sediment movements In water Intakes with Multiblock option - SSIIM) was used to simulate the velocity field and the water surface profile along the northern reach of the Tigris River using the findings of the current bathymetric survey of the river. The model was calibrated for the water levels, the velocity profiles and the sediment concentration profiles using different combinations of parameters and algorithms, those available in the model. The set of parameters that gave a minimum root mean square error (RMSE) was used for the validation process using another set of field measurements. The calibration and the validation results showed good agreement with field measurements, and the model was used to predict the future changes in river hydro-morphology for a period of 14 months. The results of the future predictions showed increases in depositions on the shallow part of the cross section having lower velocity and, on the other hand, the river deepens the incised route to fit its current hydrologic condition leaving the former wide section as a floodplain for the newer river. The net deposition/erosion rate was 67.44 kg/s in average and the total deposition quantity was 2.12 million tons annually. The locations of depositions are compatible with those of the river in the real world. An expansion in the size of current islands was predicted. An indication of the potential threats of the river banks’ collapse and the bridge piers’ instability was given by high erosion along the thalweg line.Keywords: Flood capacity, Dredging, HEC-RAS, Bathymetric survey, Bed sediment, Bedload, Total load, Helley-Smith sampler, Sediment transport, ADCP, Prediction formulas, 3-D morphodynamic model, Bed changes, SSIIM, underfit river, regulated river, Tigris River, Baghdad.

  • 6.
    Ali, Ammar A.
    et al.
    Water Resources, College of Engineering, University of Baghdad.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Suhail, Qusay
    Earth Sciences, College of Science, University of Baghdad, Iraq.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Spatial Measurement of Bed Load Transport in Tigris River2017Ingår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, nr 4, s. 55-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using Helley-Smith sampler, 288 bed load samples were collected from 16 cross sections along 18 km reach length of Tigris River within Baghdad. The spatial distribution of sampling along the reach took into consideration the variance of river topography where 7 meanders, 2 islands and several bank depositions characterize the geometry of the river. The implemented regulation schemes on Tigris River have reduced 44% of water discharges compared to previous period. The spatial variance in topography was effectively scattering the results of the applied twenty bed load formulas. The study results indicated that the complicated geometry of the river reach makes finding a unique representative bed load formula along the study reach rather difficult, and there is no grantee to have good agreement with measurements in the irregular cross sections (meanders, sand bars, etc.). The closest bed load prediction formulas were van Rijn1984. The annual transported quantities of bed load were estimated to be 30 thousand tons (minimum) in 2009 and 50 thousand tons (maximum) in 2013.

  • 7.
    Ali, Ammar Adel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Morphology of Tigris River inside Baghdad City2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Tigris and Euphrates rivers represent the artery of life in Iraq. Tigris River rises from Turkey and flows toward the southeast to enter Iraq. It drains a catchment area of 473 100 km² of which about 58% lies in Iraq. In this study the reach, about 50 km long, of the river inside Baghdad was been studied. It starts at Al-Muthana Bridge and ends at Tigris-Diyala River confluence. Generally, the river reach is part of an alluvial plain, single channel and meandering. The bed material of the river is composed mainly of fine sand and small portion of silt and clay. Other significant features of the reach are the growing islands and bank depositions. Recently water resources of Iraq are negatively affected by climatic changes and the huge water projects in the riparian countries. As a result, the flow of Tigris River at Baghdad city has significantly decreased where the average monthly flow is 520 m³/s for the period 2000-2012 which represents about 50% reduction compared to previous periods. The estimated trend for the average monthly discharges is a reduction of 5.4 % during the last 23 years. Low flow and low water levels have enhanced the water to erode the banks below its protected part. This might affect the future stability of the banks. The drop of the river discharge together with debris from the last wars in 1991 and 2003 enhanced the growing of islands in the river. In this research, changes in the morphology of Tigris River within Baghdad are to be investigated and the causes will be highlighted in order to take the right measures to restore the river system. This is a first step toward studying the hydrological characteristics of the reach. One-dimensional gradually varied flow model, using HEC-RAS, was applied to examine the flood capacity and the possibilities of inundation of the banks. The geometry of the river was represented by the findings from the river survey of 2008. Additional data about the locations and dimensions of the bridges were supplied to the model. The average monthly discharge at Sarai Baghdad for the years 2000-2012 was assumed as the base flow. A range of different scenarios were examined by increasing the discharges in order to determine the critical discharge that may cause inundation. Model calibration was achieved by adjusting the Manning’s roughness coefficient for an observed water surface profile along the lowest part of the reach. The associated error with the computed water surface profiles was in order 0.026m. Additional water level observations at Sarai Baghdad were used for verification purposes. It was found that the discharges higher than 2700 m3/s could cause partial inundation in some areas in the northern part of the reach and these areas extend to approximately 9 km for discharges greater than 3500 m3/s. The southern part of the reach is still safe from inundation for discharges below 3500 m3/s. The slope of water surface profile varies from 6.03 to 10 cm/km for discharges between 400 and 4000 m3/s respectively. In this study, a field survey was conducted between May, 2012 and January, 2013. It involved the installation of 25 bench marks, surveying the upper river banks (from the crest of the stony protection to the water surface) and 250 cross sections. Three kinds of samples were collected at this stage work: (i) river bed material, (ii) suspended load samples and (iii) bed loads samples. Hydraulic measurements were conducted and included water surface elevations, water depths at sampling points, water discharges and transversal velocities. Water temperature and other environmental measurements were also conducted. Particle size distribution, specific gravity and concentration of suspended sediment were executed in the laboratory for the collected samples.

  • 8.
    Ali, Ammar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. College of Engineering, Unive rsity of Baghdad.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Suhail, Qusay
    College of Science, University of Baghdad.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Three-Dimensional Morphodynamic Modelling of TigrisRiver in Baghdad2017Ingår i: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 11, nr 6, s. 571-594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bathymetric and land surveys were conducted for the northern Tigris River reach (18 km length) in Baghdad, producing 180cross sections. A river bed topography map was constructed from these cross sections. The velocity profiles and the water discharges were measured using ADCP (Acoustic Doppler Current Profiler) at 16 cross sections, where intensive number of sediment samples was collected to determine riverbed characteristics and sediment transport rate. The three-dimensional morphodynamic model (SSIIM (simulation of sediment movements in water intakes with multiblock option)) was used to simulate the velocity field and the water surface profile along the river reach. The model was calibrated for the water levels, the velocity profiles and the sediment concentration profiles using different combinations of parameters and algorithms. The calibration and the validation results showed good agreement with field measurements, and the model was used to predict the future changes in river hydro-morphology for a period of 14 months. The results of the future predictions showed the Tigris River which behaved like an under-fit river, increases in depositions on the shallow part of the cross section having lower velocity, and the river deepens the incised route to fit its current hydrologic condition leaving the former wide section as a floodplain for the newer river. The net deposition/erosion rate was 67.44 kg/s in average and the total deposition quantity was 2.12 million ton annually. An expansion in the size of current islands was predicted. An indication of thepotential threats of the river banks’ collapse and the bridge piers’ instability was given by high erosion along the thalweg line.

  • 9.
    Ali, Ammar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Impact of Growing Islands on the Flood Capacity of Tigris River in Baghdad City2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Growing islands became noticeable phenomena in the channel of River Tigris within Baghdad City during recent years.Despite the fact that large amount of sediments are trapped in reservoirs on the River Tigris and its tributaries thenumber of islands are increasing with time. This is due to the debris of destroyed bridges in the wars of 1991 and 2003.As a consequence the ability of the river had been reduced to pass ood waves. This fact caused ooding parts of majorcities like Baghdad. Cross sections of the River Tigris were surveyed in dierent occasions (1976, 1991 and 2008). In1977 the survey was conducted by Geohydraulique and in 1991 by University of Technology - Baghdad (extended forthe previous study). The last survey was conducted in 2008 by Ministry of Water Resources extending 48 kilometersfrom Al-Muthana Bridge till the conuence with Diyala River at intervals having horizontal spacing of 250m. The datawas used to predict the maximum ood capacity for the river using HEC-RAS through performed a one- dimensionalhydraulic model for the ow. The average discharge of the river in Baghdad had been calculated for the past ten years.This value was introduced in the model. Then dierent scenarios were applied by increasing the discharge in orderto nd out the critical discharge that can cause inundation. The procedure continued to detect the areas that had beeninundated and the water level was recorded. The primary runs for the model showed a signicant reduction in thecurrent river capacity in comparison with what the river had used to hold during oods of 1971 and 1988. The threesurveys that had been conducted on the same reach of the River Tigris indicated that the capacity of the river to passwater had been decreased. In addition the changes in the morphology of the river cross sections were very clear.

  • 10.
    Ali, Ammar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Morphology of Tigris river within Baghdad city2012Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 16, nr 10, s. 3783-3790Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Changes in the morphology of the River Tigris within Baghdad City are very noticeablein recent years. The number of islands is increasing with time despite the fact that hugeamount of sediments are trapped in reservoirs upstream Baghdad City. The debris of5 destroyed bridges in the wars of 1991 and 2003 had enhanced the development ofthese islands. As a consequence the ability of the river had been reduced to pass floodwaves. This fact caused partial flooding of parts of Baghdad City.Cross sections of the River Tigris were surveyed in three occasions (1976, 1991and 2008). The last survey conducted in 2008 by Ministry of Water Resources covered10 49 km of the river from Al-Muthana Bridge to its confluence with Diyala River at 250mintervals. The data was used to predict the maximum flood capacity for the river usingone-dimensional hydraulic model for steady flow “HEC-RAS”. Calibration was carriedout for the model using field measurements for water levels along the last 15 km fromits reach and the last 10 yr observations at Sarai Baghdad station.15 The average discharge of the river in Baghdad had been calculated for the past tenyears. This value was introduced in the model. Then different scenarios were appliedby increasing the discharge in order to find out the critical discharge that can causeinundation. The procedure continued to detect the areas that had been inundated andthe water level was recorded.20 The model showed a significant reduction in the current river capacity in comparisonwith what the river had used to hold during floods of 1971 and 1988. The three surveysconducted on the same reach of the River Tigris indicated that the capacity of the riverto pass water had been decreased. In addition the changes in the morphology of theriver cross sections were very clear.

  • 11.
    Ali, Ammar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Suhail, Qusay
    Baghdad University.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Evaluation of dredging operations for Tigris river within Baghdad, Iraq2014Ingår i: Journal of Water Resource and Protection, ISSN 1945-3094, E-ISSN 1945-3108, Vol. 6, nr 4, s. 202-213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    River Tigris divides Baghdad, capital of Iraq, in two parts. The reach of the river within Baghdad is about 60 km long. Many islands and bars are obstructing the flow of the river within Baghdad. To overcome this problem, dredging operations started along most of Tigris River inside Baghdad City to remove many islands and side bars, which reduced the flooding capacity and the efficiency of water intakes. An examination for the dredging plan under process and two proposed additional plans were performed using HEC-RAS program for a 50km long river reach to investigate whether they can recover the designed flooding capacity of the river or just improving it. Calibration and verification processes were implemented in the model using observed water levels at Sarai Baghdad gauging station and along the last 15 km of the river reach. Comparisons of computed water levels were conducted with those of previous studies and historical data. Some improvement of flood capacity was achieved based on the recorded data of the last three decades. Cautions about the water intakes should be considered to maintain their function with the expected drop in water level due to dredging operations.

  • 12.
    Ezz-Aldeen, Mohammad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hassan, Rebwar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Ammar
    Department of Water Resources Engineering, Baghdad Universi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Watershed Sediment and Its Effect on Storage Capacity: Case Study of Dokan Dam Reservoir2018Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 10, nr 7, artikel-id 858Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dokan is a multipurpose dam located on the Lesser Zab River in the Iraq/Kurdistan region. The dam has operated since 1959, and it drains an area of 11,690 km2. All reservoirs in the world suffer from sediment deposition. It is one of the main problems for reservoir life sustainability. Sustainable reservoir sediment-management practices enable the reservoir to function for a longer period of time by reducing reservoir sedimentation. This study aims to assess the annual runoff and sediment loads of the Dokan Dam watershed using the soil and water assessment tool (SWAT) model to evaluate the relative contributions in comparison with the total values delivered from both watershed and Lesser Zab River and to identify the basins with a high sediment load per unit area. These help in the process of developing a plan and strategy to manage sediment inflow and deposition. The SUFI-2 program was applied for a model calibrated based on the available field measurements of the adjacent Derbendekhan Dam watershed, which has similar geological formations, characteristics and weather. For the calibration period (1961–1968), the considered statistical criteria of determination coefficients and Nash–Sutcliffe model efficiency were 0.75 and 0.64 for runoff while the coefficients were 0.65 and 0.63 for sediment load, respectively. The regionalization technique for parameter transformation from Derbendekhan to Dokan watershed was applied. Furthermore, the model was validated based on transformed parameters and the available observed flow at the Dokan watershed for the period (1961–1964); they gave reasonable results for the determination coefficients and Nash–Sutcliffe model efficiency, which were 0.68 and 0.64, respectively. The results of SWAT project simulation for Dokan watershed for the period (1959–2014) indicated that the average annual runoff volume which entered the reservoir was about 2100 million cubic meters (MCM). The total sediment delivered to the reservoir was about 72 MCM over the 56 years of dam life, which is equivalent to 10% of the reservoir dead storage. Two regression formulas were presented to correlate the annual runoff volume and sediment load with annual rain depth for the studied area. In addition, a spatial distribution of average annual sediment load was constructed to identify the sub basin of the high contribution of sediment load.

  • 13.
    Hassan, Rebwar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ali, Salahaddin S.
    Department of Geology, University of Sulaimani, Sulaymaniyah, Iraq.
    Ali, Ammar A.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Abdullah, Twana
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dukan Dam Reservoir Bed Sediment, Kurdistan Region, Iraq2016Ingår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 8, nr 9, s. 582-596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Dukan Dam Reservoir (DDR) in the Kurdistan Region of Iraq has been studiedto determine the characteristics and nature of the reservoir and the deposited sedimentson its bottom surface. This study was achieved by doing a field survey andgrain size analyses of the collected sediment samples at 32 locations representing thewhole reservoir area that had been created when the Lesser Zab River was dammedin 1959. The Dukan Dam, which is a multi-purpose concrete arch dam, was built onthe Lesser Zab River for controlling its flood during high rainfall seasons, irrigationand power generation. The catchment area is 11,690 km2. The surface area of the reservoiris 270 square kilometers and the volume is 6.870 × 106 m3 at normal operationlevel (El. 511.00 m. a.s.l.). The minimum drawdown level is at elevation 469 mabove sea level (a.s.l.). The live storage is 6.14 × 106 m3 while the remainder is deadstorage. The reservoir has a surface area that reaches 270 square kilometers and iscomposed of two sub-reservoirs connected by a narrow channel that has a length of 5kilometers. The relatively bigger reservoir is located in the north and has a triangularshape with a surface area approximately 250 square kilometers. The smaller sub-reservoiris located down south where the dam exists and it has irregular rectangularshape. Thirty-two sediment samples were collected from the bottom of Dukan reservoir.The bed of the reservoir is mainly composed of 15% gravel, 14% sand, 48%silt and 23% clay respectively. Most of the sediments are very fine grained, verypoorly sorted, strongly coarse skewed and mesokurtic.

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