Abstract
The Fox Glacier/Te Moeka o Tuawe catchment, located in the West Coast region of Te Wai Pounamu/South Island of Aotearoa/New Zealand, experiences persistent landscape evolution by landslides, glaciers, tectonic forces, and precipitation. Signs of increasing instability of ice and sediment in the catchment include the rapid recent retreat of Fox Glacier since 2008, heightened erosion across numerous proglacial and paraglacial hillslopes and widening of the river’s margins. Landsliding and rockfall have irreparably damaged the valley’s access roads and present significant hazards to travellers in the valley, the nearby township, and road infrastructure. Quantifying changes in this area is therefore important to advancing understanding of landscape evolution and processes, particularly in the contexts of climate change and anticipated near future Alpine Fault rupture. Given the catchment’s largely inaccessible, hazardous, and vast terrain, operational and emerging remote sensing techniques provide a means to study landscape changes in the area with relative efficiency and breadth. Using multiple remote sensing data sources, this thesis quantifies 3-D changes in the Fox Glacier catchment over a five-year period and analyses major processes driving mass movements. Between 2017 and 2022, the Fox Glacier retreated 374 m to its shortest length in recorded history, with ablation on the glacier’s lower icefall destabilising adjacent hillslopes and promoting failure. Hillslope denudation exceeding 45 million m3 has been observed on landslides, debris flows, and rockfall zones over the study period. Net volume losses of 16 million m3 were observed on hillslopes directly connected to the fluvial network, implying high influx of debris and sediment into the river system. Despite this, the river shows net volume losses over the study period, suggesting high transport efficiency as a result of strong coupling between sediment sources and the fluvial network and sufficient river and stream flows – facilitated by high precipitation – to transport substantial masses through the cascading system.