Reservoir sedimentation modelling using computational fluid dynamics model :

Abstract

This work comprises modelling reservoir sedimentation using Computational Fluid Dynamics software for Kibimba reservoir. However, the knowledge about the rate and the pattern of sediment deposition is one of the important requirements for understanding sedimentation and morphological processes in the reservoir. The overall objective is to come up with a reservoir sedimentation model which will predict sediment variation as a guide to reservoir management and this will be achieved through simulation of different sedimentation processes within the reservoir during operation and flushing process in the reservoir. In order to achieve this, the following specific objectives have to be accomplished. Estimating the sediment loading from the contributing sub-catchment and the current reservoir volume is one of the specific objectives. Quantifying different kinds of sedimentation that occur in the reservoir and its distribution pattern within the reservoir is another. Finally, all the above will aid in the development of a sediment model for Kibimba reservoir and this model will be used to simulate different sedimentation processes. The project was able to come up with a model which was developed using SSIIM tool in CFD to determine various reservoir parameters using Navier Stokes equations. The analysis looks at estimating sediment loading in the reservoir from the contributing sub-catchment and estimating current reservoir volume, quantifying different kind of sedimentation that occurs in the reservoir and its distribution pattern within the reservoir and the numerical modeling. This also covers the Graphical User Interfaces (GUI) of various reservoir parameters as far as sedimentation and water level is concerned. The interfaces include both SSIIM and Paraview 5.9.0 RC3. The input values that were used in the model was from both River Malaba and River Kibimba. The annual rate of increase is 56.4% hence increase in sediment transportation in Kibimba reservoir. There was reduction of the area occupied by the reservoir from 450Ha to 442.656Ha and the volume of the reservoir was reduced from 31.4 million m3 to 25.7 million m3 This model can be re-adjusted and simplified to fit various reservoir conditions in order to carry out simulations of various reservoirs hence an application for this model.