Evaluation of the Hydraulic Performance Indicators for Al- Ibrahim Irrigation Canal in the South of Iraq

This study was concerned for steady flow in open canals of different flow conditions that may exist in irrigation system. To achieve this objective, AL-Ibrahim Canal Located South of Iraq has been selected from numerous irrigation systems having deficiencies between demand requirements and actual supply, due to a problematic of distribution and management. The field works consists the measurements of stages at outlets,at upstream, and at downstream head regulators .The study adopted nineteen actual cases of discharge along six months, two or more measurements at each month during the study period,between November 2013 to April 2014.The main objectives of the present study are; analysis the actual operation of irrigation canal and evaluated indicators then the HEC-RAS model was applied to achieve these objectives. Themax. stage and discharges measurements at head regulator during the study period was4.415 m3/sec at Jan.2014,where it less than a target discharge , so the outlets along canal should not be operated at the same time especially if the gate of the outlets are fully opened , because for entire operation numerous outlets will take discharge higher than the target.The study has shown that it doesn'toperatethe channel and access to the standard of performance but several scenarios have been prepared depending on the discharge at head regulator

Field and Satellite Images-Based Investigation of Rivers Morphological Aspects

Worldwide and especially in less developed regions, process-based evaluations and/or geomorphological information on large-scale rivers are still scarce. Such investigation become of ‎urgent ‎need due to the climate change and expected occurrence of extreme floods and drought which ‎may ‎threaten the safety of nearby and downstream cities, especially in regions that are highly sensitive and ‎affected by climatic changes. The Tigris River, in Iraq, is one such river that has undergone significant alteration to its flow and morphologic aspects due to climate change and the construction of many dams. However, morphology and its change for many reaches of this river are still uninvestigated. To this end, field and satellite-based investigations into the morphology of a reach located between Makhool District and Tikrit City have been conducted. In addition to the cross-sectional survey-based determination of the reach geometrical aspects, a sinuosity indices-based evaluation of the reach planform was implemented, utilizing a satellite indices-based approach. Furthermore, the characteristics of bed material were identified through field sampling. Investigation results show that the reach has a steep bed slope and many islands of low altitude with an elongated shape. The reach has a mild sinuosity with alternating bars. The dominant particle sizes of the bed material are coarse and medium gravel with a dominant particle shape of disc particles. Moreover, the satellite-based change detection indicated the fading out and disappearance of some secondary channels, the growth of many islands, and the movement of some bends downstream. The percentage of changing parts for the period 1975–2021 is 14%. Most of this change, 11%, occurred after the construction of the Mosul Dam. This reveals the sensitivity of reach morphology to flow change due to the construction of dams. The conducted fieldwork and the applied methodology contribute to supporting efforts to add knowledge worldwide about uninvestigated rivers. Doi: 10.28991/CEJ-2022-08-07-03 Full Text: PD

Monitoring and Modelling Morphological Changes in Rivers Using RS and GIS Techniques

River geomorphological investigation issues have received little attention in most countries of the world. Such processes become a pressing necessity due to climate change and anticipated events of extraordinary surges and dry seasons, which may debilitate the security of adjacent and downstream cities, particularly in locales that are exceedingly delicate and influenced by climatic changes. Al-Abbasia reach is a river that runs through the middle of the Euphrates River and is known for its numerous bends and meanders. The study of hydraulic structures such as barrages can provide important information about their influences on morphological processes in river reaches near the barrage upstream and downstream. Hydraulic analysis is made of the river behavior in u/s and d/s of hydraulic structures like barrages as a result of sediment deposition and erosion in u/s and d/s. A study, i.e., research on the impacts of the Abbassia barrage on the river system, has been conducted to address this issue using multi-temporal Landsat satellite data from 1976 to 2022 provided by the USGS. The study reach is located 5 kilometres upstream and 5 kilometres downstream of the Abbassia reach. Following the construction of the barrage, which had an impact on the sedimentation and geometry of the river, morphological variations took place in this part of the Al Abbassia reach. In this study, morphological changes throughout 49 years between 1976 and 2022 were investigated utilising remote sensing (RS) and geographic information system (GIS) approaches. Additionally, four image groups from three separate decades were used to perform change detection (1990–2000, 2000–2010, and 2010–2022). In this study, a monitoring system using Landsat-3 MSS: 1985, Landsat-5 TM: 1990, 1995, 2000, 2005, and Landsat-8 OLI: 2010, 2011, 2015, 2021, 2022 were employed to map river planform changes. The long-term comparison of this series of satellite images and historical maps for the period 1976–2022 indicates a continuation of change in the reach study with a rate of approximately 56, 33, 97, and 55% for upstream and 19%, 26%, 3%, and 45% for downstream for the width, area, deposition, and erosion, respectively. Furthermore, it is observed that there is a shift in river course within 200 m downstream of the barrage for the period of 1985–1990. The findings of this study, which monitor river morphological change at finer temporal and spatial resolutions, are crucial for promoting sustainable river management. They also aid in the investigation of river behaviour, which is necessary for providing the best management possible and overcoming the difficulties posed by this important research issue. Doi: 10.28991/CEJ-2023-09-03-03 Full Text: PD

Relevant Problem of a Hydraulic Jump at Diyala Weir and the Proposed Remedy

This study aims to analyze the Diyala weir problems and compares it with the safe limit and proposes the treatment for these problems. One of the most influencing problems in the site of weir was the formation of the hydraulic jump, it was found that the scour occurs due to the position of the hydraulic jump and the sequence depth of the jump is higher than the tail water depth. Some treatment procedures are suggested, these treatments cover this problem by presenting a suitable stilling basin as well as recommended to use a low weir at end of basin to produce a back water curve that should be increase the stage of tail water and ensuring the stability of a hydraulic jump

Hydraulic Characteristics and Discharge of Canal Sluice Gate: Practical Approach

Simplifying formulas that are used for calculations and design are the aim of researchers. For present work, the approach to distinguish the flow under sluice gate was conducted in a laboratory. The extensive experimental program was done to collect fifty-four data points for both free and submerged flow conditions. The data included different discharges, gate openings, flow depths at upstream as well as the flow depths represent a tail water and at a contracted section for downstream. The collected data are analyzed according to a problematic that may encounter in the field, to present a more straightforward (but with acceptable accurate) practical features equations and charts. Based on the proposed formulas, five methodologies were introduced as a guide for site engineers and beneficiary farmers. As results, necessary calculations should be followed for the purpose of the successful management of surface irrigation project by an investment of the available water to be delivered with minimizing or preventing head losses to ensure acceptable irrigation efficiency up to the farthest outlets

Kinetic Energy Dissipation on Labyrinth Configuration Stepped Spillway

In present work a labyrinth (zigzag), in shape has been used to configure the steps of stepped spillway by using the physical model. This configuration does not introduce previously by investigators or in construction techniques of dams or cascades. It would be expected to improve the flow over chute. A magnifying the width path of each step to become, LT, instead of, W, will induce the interlocking between the mainstream and that spread laterally due to labyrinth path. This phenomenon leads to reduce the jet velocities near the surfaces, thus minimizing the ability of cavitation and with increasing a circulation regions the ability of air entrainment be maximized. The results were encouraging, (e.g., the reverse performance has recorded for spillway slope). From the evaluation of outcome, the average recorded of percentage profits of kinetic energy dissipation with a labyrinth shape compared with the results of traditional shape were ranged between (13- 44%). Different predictive formulas have been proposed based on iteration analysis, can be recommended for evaluation and design.</span

Kinetic Energy Dissipation on Labyrinth Configuration Stepped Spillway

In present work a labyrinth (zigzag), in shape has been used to configure the steps of stepped spillway by using the physical model. This configuration does not introduce previously by investigators or in construction techniques of dams or cascades. It would be expected to improve the flow over chute. A magnifying the width path of each step to become, LT, instead of, W, will induce the interlocking between the mainstream and that spread laterally due to labyrinth path. This phenomenon leads to reduce the jet velocities near the surfaces, thus minimizing the ability of cavitation and with increasing a circulation regions the ability of air entrainment be maximized. The results were encouraging, (e.g., the reverse performance has recorded for spillway slope). From the evaluation of outcome, the average recorded of percentage profits of kinetic energy dissipation with a labyrinth shape compared with the results of traditional shape were ranged between (13- 44%). Different predictive formulas have been proposed based on iteration analysis, can be recommended for evaluation and design

Predicting the Flow Velocity at the Toe of a Labyrinth Stepped Spillway

The velocity at the toe of a spillway is a major variable when designing a stilling basin. Reducing this velocity leads to reduce the size of the basin as well as the required appurtenances which needs for dissipating the surplus kinetic energy of the flow. If the spillway chute is able to dissipate more kinetic energy, then the resulting flow velocity at the toe of spillway will be reduced. Typically, stepped spillway is able to dissipate more kinetic energy than that of a smooth surface. In the present study, the typical uniform shape of the steps has been modified to a labyrinth shape. It is postulated that a labyrinth shape can increase the dissipation of kinetic energy through increasing the overlap between the forests of nappe will circulating the flow that in turns leading to further turbulence. This action can reduce the jet velocities near the surfaces, thus minimizing cavitation. At the same time the increasing of circulation regions will maximize the opportunity for air entrainment which also helps to dissipate more kinetic energy. The undertaken physical models were consisted of three labyrinth stepped spillways with magnification ratios (width of labyrinth to width of conventional step) WL/W are 1.1, 1.2, and 1.3 as well as testing a conventional stepped spillway (WL/W=1). It is concluded that the spillway chute coefficient is directly proportional to the labyrinth ratio and its value decreases as this ratio increases

Określanie lokalizacji odsypiska na podstawie badań eksperymentalnych

Morphological relationships of meander evolution in terms of hydraulic and geometric characteristics are essential for river management. In present study, an experimental based study of meander evolution was employed to develop a prediction formula for identifying the pool-point bar location by using the dimensional analysis technique and multiple nonlinear regressions. Through the experimental work on a race of the non-uniform river sand, a set of experimental runs have been carried out through combining different hydraulic and geometric parameters to produce different empirical conditions that have a direct impact on the pool-point bar location. Based on the experimental observations and measurements, the variation in pool–point bar locations could be interpreted to that the hydraulic and morphologic properties through the meander evolution were varied during the time causes the variations in the patterns of the pool-point bar formations accordingly. The developed formula was verified by using another set of the experimental data and tested with three statistical indicators. The predicted results indicated that the proposed formula had high reliability for practical estimation of the pool-point bar location. This reliability was tested by the statistical indicators, where the less values have been resulted for bias and mean absolute error (MAE), 0.0004 and 0.0110 respectively, whereas the higher values 0.935 and 0.930 are achieved for the Nash–Sutcliffe efficiency (NSE) and the determination coefficient R2, respectively.Morfologiczne zależności rozwoju meandrów, określane cechami hydraulicznymi i geometrycznymi, są ważne dla gospodarki wodnej. W przedstawionej pracy opisano eksperymentalne badania rozwoju meandrów celem uzyskania prognostycznego wzoru do określenia lokalizacji odsypiska z użyciem techniki analizy wymiarowej i wielorakiej regresji nieliniowej. Przeprowadzono serię eksperymentów nad przemieszczaniem niejednorodnego piasku rzecznego poprzez łączenie różnych parametrów hydraulicznych i geometrycznych, aby osiągnąć różne warunki doświadczalne, które mają wpływ na lokalizację odsypiska. Na podstawie obserwacji i pomiarów z doświadczeń zmienność lokalizacji można interpretować jako zmienność w czasie hydraulicznych i morfologicznych cech tworzenia meandru, które odpowiednio zmieniają położenie odsypiska. Uzyskany wzór weryfikowano, używając innego zestawu danych eksperymentalnych i testowano za pomocą trzech wskaźników statystycznych. Wyniki wskazują, że proponowany wzór ma dużą wiarygodność w praktycznym szacowaniu lokalizacji odsypiska. Wiarygodność tę sprawdzono za pomocą wskaźników statystycznych, w których uzyskano mniejsze wartości dla błędu systematycznego – 0,0004 i średniego błędu bezwzględnego (MAE) – 0,011, podczas gdy wyższe wartości osiągnięto dla współczynnika efektywności Nasha–Sutcliffe’a (NSE) – 0,935 i współczynnika determinacji R2 – 0,930

Experimental investigation of local scour under two oblong piers of a bridge crossing a sharp bend river

Bridges built across a river bend and supported by more than one pier has been experimentally studied regarding the shape and nature of erosion and deposition. For this purpose, a U-shaped laboratory channel was used with two oblong piers installed at different locations. The first one was at the mid-section of the upstream straight reach, whereas in the second site within the bend, the piers have been installed at sections of central angles 0°, 30°, 60°, 90°, 120°, 150°, 170°, and 180°, from the beginning to the end of the bend segment respectively. The studies were conducted under clear water and threshold flow conditions. The results show that the higher and lower values of local scour around the pier positioned close to the outer bank, are 1.803 and 0.623 times the pier width when the bridge was installed at an angle of 90° and 30° respectively. As for the pier close to the inner bank, the deepest local scour was 1.786 times of the pier width when the bridge was installed at 60° of the bend, while the least one was 0.516 times of the pier width when the bridge was located in the 180° sector. It is worth noting that the presence of piers within sector 150 is less affected by local scour than in the other sections