Australian Digital Theses Program

Thesis Details
Title	EVALUATION OF SEDIMENTATION PROCESSES IN A COASTAL LAKE: CAUSEWAY LAKE, THE CAPRICORN COAST CASE STUDY
Author	Soetanto, Budi
Institution	Central Queensland University
Date	2007
Abstract	This thesis presents analysis of the hydrodynamic and sedimentation changes of the Causeway Lake, Queensland. It was created in 1939 when a causeway and bridge construction was built across the estuary entrance. Since the construction, significant sediment retention has occurred in the lake. The sediment study presented in this thesis was undertaken based on historical data, field data measurement and numerical modelling, supported by theoretical analysis. Based on bathymetry data for the period from 1986 and 2003, an average of 2500 m3/year of sediment has settled in the estuary. To verify the sources of sedimentation, field measurements were undertaken at selected sections at two upstream boundaries (Mulambin and Shoal Creeks), and at the downstream boundary under the bridge. Four sets of field measurements with tidal elevation up to 4.5 m (0.8 m above the bridge sill) were analysed. Results showed that sediment transport in from the sea side was about 1050 m3/year and from the catchments area was in the order of 1100 m3/year (wash load was not included). Implementation of numerical modelling using RMA required calibration using field data. The predicted sediment transport was in order of 2900 m3/year. The calibrated model was used to simulate the sedimentation pattern for the next 10 years. Four scenarios were analysed, and the resulting recommendation was to dredge out about 141,000 m3 sediment from the Mulambin Creek branch area. Other solutions were also suggested: improvement of lake management and possibility to raise the sill level (water gate).
Thesis	01front.pdf 352.3 Kb 02section1.pdf 2504.8 Kb 03section2.pdf 2836.1 Kb 04appendices.pdf 804.2 Kb