The Effect of Thickness and Number of Permeable Obstacles on Density Current Control and Trapping

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Alireza Jahangir ¹ , Kazem Esmaili ² , Mahmoud Faghfour Maghrebi ³

1 - PhD Student, Department of Water Eng., Ferdowsi University of Mashhad, Mashhad, Iran
2 - Associate Professor, Department of Water Eng., Ferdowsi University of Mashhad, Mashhad, Iran
3 - Professor, Department of Civil Eng., Ferdowsi University of Mashhad, Mashhad, Iran

Received: 2020-06-02 Accepted : 2020-07-26 Published : 2021-05-22

Keywords: Obstacle Thickness, Suspended Sedimentation, Number of Obstacles, Permeable Obstacle, Density current,

Abstract :

Understanding and studying the river flooding, which in most cases is density current, can help to reduce adverse effects of sedimentation. To this end, the creation of obstacles in the bed of stream will be effective. In this paper, the effect of thickness (dimension) and the second layer of permeable obstacles on the control and trapping of density current is investigated experimentally. For this purpose, two types of groove and cavity obstacles with grooves and cavity diameters equal to 3 mm and made of plaque glass were used. Density currents were created by adding an insoluble, suspended polymer of expanded polystyrene with a mean diameter of 1.15 mm and a density of 1.155 g / l. The experiments utilized two different concentrations (10 and 20%), five different porosities, four different angles, four different thicknesses and two barrier layers. The results showed that the density current process with 10% porosity of the groove obstacle increased with increasing thickness. The second layer of obstacles have increased the material passage through both groove and cavity obstacles. This increase was recorded in the groove type of 1.96 and the cavity type of 2.34. Investigations showed that the optimal distance of the second obstacle from the first was 2.25 meters. According to the results, under similar conditions, cavity obstacles always perform better than groove ones.

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