Please use this identifier to cite or link to this item: http://localhost:8081/jspui/handle/123456789/17473
Title: SEDIMENT CONTROL IN AN ESTUARINE HARBOUR BASIN USING SUBMERGED VANES AND A CURRENT DEFLECTING WALL
Authors: Banuelos, Adrian Montero
Keywords: Water;Nowaday;Current Deflecting Wall;Submerged Vanes
Issue Date: Jun-2013
Publisher: I I T ROORKEE
Abstract: A harbour basin can be defined as the protected water area that provides safe and suitable accommodation for ships, condition that leads to a conflict of interest since in order to satisfy such conditions the water in the basin must be reduced. As consequence the harbour offers ideal conditions for suspended sediment to settle, where it rapidly reduces navigable depth and thus impedes navigation and along with it the economic development of the Port. Nowadays, maintenance dredging is the most common and used measure, an expensive and temporary solution that it has become in a continuing and unrelenting burden, since ports activities are interfered during dredging operations, in addition to ongoing costs of dredging. A relative new approach is the use of sediment control measures designed to Keep the Sediment In the System (KSIS) by applying an Entrance Flow Optimization Systems (EFOS) to avoid the entrance and deposition of particles in the harbour. However these solutions need to be tailored for each harbour with a unique and specific set of conditions. This study aims to study the effect of Submerged Vanes (SV) and a Current Deflecting Wall (CDW) placed near the harbour entrance in the water and sediment exchange mechanisms. A three-dimensional processbased model, Delft3D was set up for the harbour and area of the estuary involved in the sedimentation problem. Complex multidimensional boundary conditions were developed from the data measured and provided by Kolkata Port Thrust, to simulate the rate of exchange between an schematic harbour and its estuarine water system without and with SV & CDW. A very fine grid with non-hydrostatic pressure inclusion is used to simulate the sediment control measures and entrance, whereas for the rest of the area within the tidal excursion range is analyzed assuming hydrostatic pressure distribution and a coarser grid. Using the Fixed-layer schematization in vertical direction, Horizontal Large Eddy Simulation and hydraulic structures features of the modelling suite, for the proper simulation and study of the vanes induced three-dimensional helical flow ii I Page across the harbour entrance. It was proposed to study the effectiveness of sediment control measures in an ideal scenario of the Haldia Dock Complex (as ungated) within the Hooghly Estuary with the purpose of analyzing a real world system, instead of an idealization of scenario. However the measures are implemented and analyzed in a schematic model of simpler geometry and configuration. The model simulated water exchange mechanisms between a harbour and its water system are in agreement with the theoretical description found in the literature. Submerged Vanes are found to be a potential measure to arrest harbour sedimentation, since a tidal average reduction of 47.62% in the exchange due to density currents was achieved with its implementation and 27.31% in the total water exchange. Vanes have a significant influence in the flow field near the harbour entrance, where it reduces the velocity of the river in front of the harbour entrance minimizing the difference of velocities that generates the gyre and consequently the mixing layer. The intercepting scheme effectively reduces water exchange rate for values of specific discharge between 0.40 and 0.50, however its performance decreases drastically for values beyond 0.70. As reported in literature and appreciated in the results, the Current Deflecting Wall without sill dominates the reduction in the horizontal entrainment with a tidal average percentage of 46.66, an increase of 6.57°h on density currents and 32.28% decrease in tidal filling, for total average reduction of 32.69%. The efficacy of the CDW follows a concave parabola where reduction values above 50% are between a range of 0.55 to 0.70 specific discharge ratio, while it decays gradually for values lesser than 0.50 and greater than 0.75. The simulation of the combined measure: Submerged Vanes and Current Deflecting Wall was not possible, nevertheless by inference of the results vanes and CDW are found to be a promising combination. The wall would deal with the exchange due to horizontal entrainment while the vanes arrest the formation of density currents and divert the sediment from the harbour entrance. Together would contribute to the reduction of horizontal entrainment and ultimately a substantial decrease on harbour sedimentation could be achieved.
URI: http://localhost:8081/jspui/handle/123456789/17473
metadata.dc.type: Other
Appears in Collections:MASTERS' THESES (WRDM)

Files in This Item:
File Description SizeFormat 
G23057.pdf40.07 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.