| 1. |
- Ali, Ammar A., et al.
(författare)
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Sediment flux from Lesser Zab River in Dokan Reservoir : Implications for the sustainability of long‐term water resources in Iraq
- 2020
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Ingår i: Rivers Research and Applications. - USA : John Wiley & Sons. - 1535-1459 .- 1535-1467. ; 36:3, s. 351-361
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Tidskriftsartikel (refereegranskat)abstract
- Prudent management of Iraqi water resources under climate change conditions requires plans to be based on actual figures of the storage capacity of existing reservoirs. With the absence of sediment flushing measures, the actual storage capacity of Dokan Reservoir (operated since 1959) has been affected by the amount of sediment delivered during its operational life leading to an undetermined reduction in its storage capacity. In consequence, there has not been an update on the dam's operational storage capacity curves. In this research, new operational curves were established for the reservoir based on a recent bathymetric survey undertaken in 2014. The reduction in reservoir capacity during the period between 1959 and 2014 was calculated by the mean of the difference between the designed storage capacity and the storage capacity which was concluded from the 2014 bathymetric survey. Moreover, the rate of sediment transported to the reservoir was calculated based on the overall quantities of accumulated sediment and the water discharge of the Lesser Zab River into the reservoir. The results indicate that the dam capacity is reduced by 25% due to sedimentation of an estimated volume of 367 million cubic metres at water level 480 m.a.s.l. The annual sedimentation rate was about 6.6 million cubic metres, and the sediment yield was estimated to be 701.2 t∙km−3∙year.
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| 2. |
- Ezz-Aldeen, Mohammad, et al.
(författare)
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Watershed Sediment and Its Effect on Storage Capacity : Case Study of Dokan Dam Reservoir
- 2018
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Ingår i: Water. - : MDPI. - 2073-4441. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Hassan, Rebwar, et al.
(författare)
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Bathymetry and siltation rate for Dokan Reservoir, Iraq
- 2017
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Ingår i: Lakes & Reservoirs. - : John Wiley & Sons. - 1320-5331 .- 1440-1770. ; 22:2, s. 179-189
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Tidskriftsartikel (refereegranskat)abstract
- The Dokan Reservoir dam is a concrete cylindrical arch with gravity abutments, located on the Lesser Zab River about 60 km from the city of Sulaimani in north-eastern Iraq. A bathymetric survey was conducted in November 2014 for a period of 10 days, using an echo sounder of 200-kHz single beam. The survey results indicated an annual average sediment deposition of 3.8 million m3. Thirty-two sediment samples were collected from the reservoir bed. The ratio of gravel, sand, silt and clay was 15:14:48:23, respectively. The reservoir bed is covered mainly with silt. The sediments are composed of silty clay (77.6%), silty sandy clay (10%), sandy gravely silty clay (1.2%) and gravely sandy silty clay (1%).
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| 4. |
- Hassan, Rebwar, et al.
(författare)
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Dukan Dam Reservoir Bed Sediment, Kurdistan Region, Iraq
- 2016
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 8:9, s. 582-596
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 5. |
- Hassan, Rebwar, et al.
(författare)
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Reduction in the Storage Capacity of Dokan Dam Reservoir
- 2019
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Ingår i: Advances in Sustainable and Environmental Hydrology, Hydrogeology, Hydrochemistry and Water Resources. - Switzerland : Springer Nature. - 9783030015718 - 9783030015725 ; , s. 429-432
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Konferensbidrag (refereegranskat)abstract
- Dokan reservoir is located on the Lesser Zab River NE Iraq. Its drainage area is 11,690 km2 with a storage capacity of 6.87 × 109 m3. Calculation of the volume of the reservoir before the construction of the dam and from the bathymetric survey conducted in 2014 indicates that an annual average of 7 million cubic meters of sediments are deposited within the reservoir. This reduced the storage capacity of the reservoir by 28%.
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| 6. |
- Hassan, Rebwar, 1959-
(författare)
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Sediment Characteristics and Sedimentation Rate Estimation in the Dukan Reservoir
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Dukan Reservoir has been created from the construction of the Dukan Dam on the Lesser Zab River where it crosses the Khalakan Thrust Sheet (Khalakan Mountains) through a gorge 65 km northwest of Sulaimani and 295 km northeast of Baghdad. The Dukan Dam is a multi-purpose dam which was built from 1954 to 1959 to control the flooding of the Lesser Zab River, and to provide irrigation, hydroelectricity, and water storage. Reservoir sedimentation can significantly reduce reservoir storage capacity as dams become older. The Dukan Reservoir has been selected for this study to determine the nature and characteristics of the deposited sediment particles in the reservoir, as well as the estimation of the rate of sedimentation from 1959 to 2014 by using the bathymetric survey and the Soil and Water Assessment Tool (SWAT) model methods.Geologically, the Dukan Reservoir is located in the High Zagros Fold-Thrust Zone (High Folded Zone) of the northwestern segment of the Kurdistan Zagros Fold-Thrust Belt. This reservoir is a natural and structurally controlled depression located in the Btwen (Ranya) Agricultural Plain extending between the Ranya Thrust Sheet (Kewa-Rash Mountains) and the dam body itself. A geological survey was conducted for the study area and it has been concluded that the structural controls were more effective by dividing the Dukan Reservoir into two sub-reservoirs: a bigger triangle-shaped sub-reservoir in the north and a smaller irregularly shaped sub-reservoir in the south. The differences that exist in shapes, lengths, widths, surface areas, and shorelines between the two subreservoirs are also closely related to the structural and stratigraphical controls. The field observations and bathymetric survey indicate that bank sediment erosion is occurring in the two sub-reservoirs, but most of the sediment particles deposition takes place within the bigger sub-reservoir. Grain analyses of the 32 bed sediment samples show that the reservoir bed sediment consists of 15% gravel, 14% sand, 48% silt, and 23% clay. The sediments are composed of silty clay (77.6%), silty sandy clay (10%), sandy gravelly silty clay (1.2%) and gravelly sandy silty clay (1%). The reservoir bed is covered mainly with silt. Both silt and clay percentages increase towards the dam in the smaller sub-reservoir. This is attributable to the decreased water velocity in the reservoir, leading to the deposition of the suspended materials. The sediments are very finegrained, very poorly sorted, strongly coarse skewed, and mesokurtic. The depositedsediment along the Dukan Reservoir can be classified into topset bed (coarse particles) and bottomset bed (fine materials). The slope of the western bank of the reservoir is steeper than the eastern and northern banks. Land slope is the most effective factor in erosion and sediment transport. From the bathymetric survey, it has been also concluded that the minimum elevation which reaches 430 m.a.s.l. is located at the southern part of the bigger sub- reservoir. Based on different bulk densities of the deposited sediment at different water elevations, i.e., 1855 kg/m3 at 470 m.a.s.l., 1855 kg/m3 at 480 m.a.s.l., and 1200 kg/m3 at 480 m.a.s.l., the annual sedimentation rates in the reservoir are estimated to be about 3.8 MCM, 7 MCM, and 6.6 MCM, respectively. This estimation has been supported by the SWAT model method, which shows that the annual sediment load delivered to the Dukan Reservoir from the watershed is estimated to be about 1.3 MCM, representingabout 34% of the total sediments deposited in the reservoir.The reduction in storage capacity of the bigger sub-reservoir from 1952 to 2014 at water elevations 440 m.a.s.l., 460 m.a.s.l, and 480 m.a.s.l. are 72%, 48%, and 24%, respectively. The volume of the deposited sediment is estimated to be around 274 MCM. The percentage of the smaller sub-reservoir area as a percentage of the whole reservoir area varied in 1952 from 4% at water level 520 m.a.s.l. to 100% at 420 m.a.s.l. The author predicts that the estimated annual deposition rate of 6.6 MCM and the projected useful lifespan might extend for another 155 years until 2169, when the sediment will fully occupy the live storages.
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| 7. |
- Sissakian, Varoujan K., et al.
(författare)
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The Regional Geology of Dokan Area, NE Iraq
- 2016
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Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 6:3, s. 35-63
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Tidskriftsartikel (refereegranskat)abstract
- The northern and northeastern part of Iraq, which includes the Iraqi Kurdistan Region, is characterized by mountainous area with very rugged relief. The difference in relief may reach up to 1000 m and locally more when the height reaches up to 3600 m (a.s.l.). The mountains usually represent anticlines, whereas the depressions are represented by synclines. The Lower Cretaceous rocks usually form the carapace of the mountains, whereas the soft clastics of Upper Cretaceous and Paleocene form the synclines. However, some exceptions occur when the area is affected structurally by main faults. The main trend of the anticlines in the study area is NW – SE, which are dissected by either NE – SW normal faults or by reverse and/ or thrust faults oriented in NW – SE trend; however, some exceptions occur too. The Dokan area is characterized by a large depression in which the Lesser Zab River was flowing; before construction of Dokan dam (1954 – 1959). The depression is a big one with surface area of about 260 Km2. The height at the surface of the reservoir when filled to normal operational level is 511 m (a.s.l.); however, the depression is surrounded; almost from all sides by high mountains that range from (800 – 1300) m (a.s.l.).he depression is believed to be structurally controlled, a normal fault with NE – SW trend had dissected the southwestern limb of Ranya anticline, the eastern block being the down thrown one that had formed the depression, besides the exposure of soft rocks of Sarmord, Chis Gara, Barsarin and Naokelekan formations that form the core of Ranya anticline. The regional geology of Dokan area including structure and tectonics, stratigraphy and geomorphology is discussed aiming to explain the development of the large and wide depression in a mountainous area.
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