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Hillslope gully erosion in savanna rangelands tributary to the Great Barrier Reef: Investigation of hydrogeomorphic processes, sediment and nutrient yields
Dissertation   Open access

Hillslope gully erosion in savanna rangelands tributary to the Great Barrier Reef: Investigation of hydrogeomorphic processes, sediment and nutrient yields

Jack Koci
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast
2020
DOI:
https://doi.org/10.25907/00664
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Hillslope gully erosion in savanna rangelands tributary to the Great Barrier Reef- Investigation of hydrogeomorphic processes, sediment and nutrient yields_Redacted9.79 MBDownloadView
Thesis Open Access

Abstract

hydrological connectivity rangeland management runoff soil erosion structure-from-motion photogrammetry water quality
Gully erosion is a globally significant land degradation problem and a particularly important issue in dry-tropical savanna rangelands tributary to the Great Barrier Reef (GBR) World Heritage Area, Queensland, Australia. In this region there is an estimated 87,000 km of gullies, providing the primary source of sediment and particulate nutrients (e.g., nitrogen and phosphorus) to the GBR. Remediating gullied landscapes and preventing further degradation is a major focus of government investment aimed at improving the quality of water entering the GBR. Effective management of gully erosion in these catchments, and tropical savannas more broadly, is constrained by a limited understanding of the key hydrological and geomorphological processes driving gully development. The effect of changing land management on sediment and nutrient fluxes within gullied catchments is also poorly understood. The overarching aim of this thesis is to improve understanding of the hydrogeomorphic processes controlling hillslope gully erosion and the associated fluxes of sediments and nutrients in savanna rangelands tributary to the GBR. Specifically, the thesis investigates: (1) the strengths and limitations of aerial (via an Unmanned Aircraft System, 'UAS'), and ground-based (via a handheld digital camera, 'GB') structure from motion with multi-view stereo photogrammetry (SfM), in quantifying the topographic expression of gullied savanna landscapes at different scales; (2) linkages between fine-scale hydrological connectivity pathways and gully hydrogeomorphic processes; and (3) the effect of reduced grazing pressure on sediment and nutrient yields in ephemeral streams draining gullied savanna rangelands.

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