Innovative Analysis of Large River Topography and Dynamics (Ref:4243)

点击翻译按钮获取中文摘要

Fluvial system sustainability is vital for a half billion riparian residents of global river floodplains and deltas, and it requires knowledge and understanding of the land surface changes through time in response to anthropogenic and climatic forcing. Germane to such understanding are high quality topographic data enabling the quantification of surface morphology and change, which are essential for understanding responses of lowland sedimentary systems to these forcings. However, global topographic data are of insufficient quality and resolution, creating major challenges for managing lowland river-floodplain complexes in large alluvial rivers. This scarcity of topographic data is especially applicable to low-gradient tropical rivers where 1) accurate topographic survey data are scarce, 2) floodplains have significant vegetation precluding satellite observation of surfaces, and 3) previous global data (eg., SRTM) are technically limited in terms of accuracy and resolution for geomorphic applications. The TanDEM-X high-resolution SAR mission (directory.eoportal.org/web/eoportal/satellite-missions/t/tandem-x) offers a way forwards, especially when paired with remote sensing data and machine learning statistical methods.Our exploratory work with the high-resolution (~12m) TDX product in Amazonia and SE Asia has identified means to remove trees using a combination of tomographic analysis, remote sensing, and machine learning using GPUs - producing bare earth DEMs for fluvial systems that can be verified for locations where we have field survey and Lidar data from prior and current NERC, NSF, and NASA-funded projects. The PhD student would focus on the refinement and application of these novel data and techniques towards quantifying the topography and evolution of project rivers - the lower Mekong River and large portions of the Amazon, major river systems that can be used to calibrate and test these approaches in coordination with ongoing NERC-funded research. Following this verification and refinement against available data, the student would work with the supervisorial team to identify and pursue a range of intriguing scientific questions for additional research locations, thus providing the PhD candidate flexibility and intellectual independence to realize their own interests and pursue new opportunities for transformative research. Project Aims and MethodsAfter refining the analytical methods for study areas with suitable field data, the PhD research would focus on quantifying the floodplain topography and gradients that drive flow, sediment transport, and river evolution for research sites, providing novel scientific insight into the functioning of fluvial systems. To further evaluate observed relationships, the student would work closely with the supervisorial team to design the reminder of their PhD research. For example, potential causal mechanisms identified for study rivers could be tested using models for fluvial morphodynamics (both standard and Exeter research models). Measurements and predictions could be verified against extensive Exeter field datasets available for the study systems and elsewhere, with possibilities for fieldwork. The ultimate aim of this PhD will be to produce generic findings about the functioning and complex evolution of large river systems that are suitable for publication in prominent journals, preparing the student for further career success.