Executive Summary : | Gabion weir is porous broad crested weir filled with locally available stones, boulders, gravels, cobbles, having different shape and size. A geosynthetic material behaves as a filter that permits flow of water through its surface while preventing the flow of sediment particles with the flowing fluid during the intended period of use. Geosynthetic protection structures of the seashore can be placed in various places of the coastal zone and constitute elements. These structures can be made of single, large-size elements (geotubes or geocontainers) protecting the seashore and fulfilling the functions of, for example, coastal bands, enabling the rebuilding of the beach, as well as consisting of many geosynthetic elements.
The major focus of the proposed study is to identify the flow characteristics of the geosynthetic-gabion weirs in an open channel. Numerous studies has been undertaken by various researcher on solid weirs and gabion weir while no study was conducted on geosynthetic-gabion weirs. still more experimental study is required to be made for flow and turbulence characteristics of geosynthethic and gabion weirs at free surface and submerged flow condition. In the proposed proposal, the experimental and numerical study will be conducted permeable weirs made up of gabion, geosynthetic and their composite material. Experiments will be performed for geosynthetic weir, gabion weir, geosynthetic-gabion weir and solid weirs of the constant crest width, the length (B), and three different crest heights (P). The experimentation will be conducted for through-flow, free and submerged flow condition. This study provides the flow properties and their variation with porosity and diameter of material of the geosynthetic and gabion weir. The turbulence characteristics of these permeable weir will also be measured and three-dimensional velocities and turbulence parameter will be measured using an PIV or acoustic doppler velocimeter (ADV). The detailed study using CFD modelling has been carried out for geosynthetic-gabion weir. This study is very useful in managing the river and ocean system system in the respect of environmental risk assessment of a water resources project. The use of geosynthetic gabion weir in a river is advantageous in reducing the material cost and reducing the environmental hazards over other types of solid structures. The depth of scour at downstream of geosynthetic gabion weir is much smaller as compared to the solid structure which reduces the foundation depth and construction cost. The hydraulic designers and water resources engineers are interested to know the fundamental and structural performance of geosynthetic and gabion weirs in all respects. However, no specific guidelines on the flow characteristics and hydraulic performance for geosynthetic and gabion weir are available. |