Long-term Trends in Sediments from a Key Great Barrier Reef Catchment: Evidence Towards Management Efforts

Chaithanya, B P (2025) Long-term Trends in Sediments from a Key Great Barrier Reef Catchment: Evidence Towards Management Efforts. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Chaithanya B P (20MS216)) 20MS216_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Abstract: This study investigates the long-term Total Suspended Sediments (TSS) trends in a key GBR catchment using a flexible statistical model called WRTDS. The trend results suggest improvement at the End-of-System site with reducing TSS concentration over the years, which is also reflected in the model output that suggests the flushing of high TSS during low discharges at the beginning of the wet season is no longer occurring for this site. A significant component of the trend reduction comes from the changes happening within the catchment, other than discharge. It is observed that the component of trend driven by discharge tends to deteriorate the overall water quality and oppose the efforts from management. This discharge-driven trend is seen to be controlled by the BFD for the sites along the Burdekin river, and the contribution of this trend to overall water quality is likely to increase in the future, as more frequent extreme events occur with warming, thus posing a challenge to future water quality. Despite the limitations in data from upstream sites, the trends have significant contributions from changes happening within the catchment. We also observe that the flow-normalized concentration values hold promise in acting as a valuable link between water quality trends and management efforts, which is not observed in the simple annual average concentration values. Thus, the wealth of inferences from this critical catchment gives an understanding of how the efforts for remediating the water quality issue are reflected in the longterm trend. Studies such as these allow exploring several aspects of the model, delve deeper into the region of interest, and can be beneficial in developing well-informed large-scale studies. Building on recent advances in data availability of GBR catchments by James et al. (2025b) and the large-scale application of WRTDS by Guo et al. (2025a), this study supports the potential for broader application of the WRTDS model across the GBR catchments, provided the data meet model requirements.

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