The construction of stilling basin with adverse slope change the characteristics of hydraulic jump such as sequent depth ratio, length of jump ratio, length of roller and energy dissipation ratio, consequently the dimensions of stilling basin are changed, also using baffle blocks with different configurations develop these characteristics. In this study different shapes of baffle block (models (A), (B), (C) and (D)) installed in the stilling basins at adverse slopes (- 0.03, - 0.045, - 0.06) in addition to horizontal bed, all these models are tested in the stilling basin to show their effects on the characteristics of hydraulic jump, the experiments applied for the range of Froude number (Fr1) between 3.99 and 7.48. The baffle block model (D) showed good results when compared with models (B) and (C), therefore it used with arrangement of (single and double row) and compared with baffle block model (A) at slopes (0, - 0.03, - 0.045, - 0.06) to study the effects of baffle blocks on hydraulic jump when bed slopes are changed. In general using baffle block caused a reduction in sequent depth ratio, length of jump ratio and the length of the roller, but the energy dissipation ratio increased.
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: PDF
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