Melville, BShamseldin, AFarjood, Arash2016-07-1120162016https://hdl.handle.net/2292/29352This thesis describes a laboratory experimental study to investigate performance of a scale model of a sediment retention pond, with the aim of improving the understanding of the effect of physical design features on its hydraulic performance and sediment removal performance. The experiments were conducted using a 1:10 scale model of a field sediment retention pond. Several configurations of the model pond with different widths of inlet, design of outlet, and location, number and type of baffles were examined. All of the experiments were conducted at steady state condition with fixed flow rates. Tracer experiments, using Rhodamine WT tracer dye, formed the majority of the experiments, from which residence time distribution curves (RTDs) were obtained and analysed. In addition, the tracer dye was visually observed to identify the zones of short-circuiting. Sediment removal performance was evaluated for a number of pond configurations, by measuring water turbidity at the outlet. The turbidity was caused by addition of a representative sediment (silica flour) to the pond. Velocity fields were also measured for inspecting the effect of spatial velocity variations on sediment removal performance. In addition to physical modelling, a CFD technique was employed for numerical investigation of pond configurations with different length-to-width ratio and bank slopes. The results showed that reducing the width of the inlet (to 85% of pond’s width) to avoid the shallow water over the sloping side walls, and modifying the outlet to avoid disrupting the flow streamlines, both improved hydraulic performance. Installation of submerged solid baffles, and different types of porous baffles, further increased the pond’s hydraulic performance, albeit to different degrees. Sediment removal performance was also increased when baffles were incorporated. Comparison of hydraulic performance and sediment removal performance indicated a strong correlation between these two measures. In addition, the data collected from the tracer experiments were scrutinised, and a new index was developed for quantification of the hydraulic performance of ponds and wetlands. The results of CFD modelling showed that pond configurations with aspect ratio of 5:1 or larger, and (for a given aspect ratio) with a bank slope of 2:1, had higher hydraulic performances. This research is the first to extensively investigate details and locations of baffles for improving hydraulic performance of sediment retention ponds. It can provide useful information for improving the performance of ponds by altering their design. In addition, a new index was developed for ponds and wetlands, which can contribute to a more enhanced analysis of hydraulic performance in ponds and wetlands of different layouts and configurations.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttps://creativecommons.org/licenses/by-nc-nd/3.0/nz/ThesisCopyright: The Authorhttp://purl.org/eprint/accessRights/OpenAccessQ112930955