Overview

Project Highlights:

 

  • Assess the long-term landscape evolution of the Bailong River Basin near Zhouqu, China
  • Develop a physical process model of geohazards (landslides, debris flows, floods) and evaluate the influence of neotectonics, climate and human interventions in the landscape
  • Enhance opportunities for sustainable development and effective geohazard risk management.

Overview 

This exciting PhD will develop physical process-based, present-day and future geohazard risk scenarios for the Zhouqu area of the Bailong River Basin (Z-BRB), Gansu Province, China. This area covers some 300 km2 and is characterised by a very dynamic natural environment where lives, livelihoods and critical infrastructures are at risk from flooding, debris flows and landslides. Recent examples include the 2010 Zhouqu debris flow disaster that killed more than 1700 people (Dijkstra et al., 2012) and the July 2018 Nanyu landslide that destroyed the major road transport link to Zhouqu, dammed the Bailong river and caused flood damage resulting from an 8m rise in water levels upstream from the landslide dam.

The Z-BRB area is characterized by a neo-tectonically active environment with high topographic relief and elevations ranging from 1200m to more than 4000m. Landslides include large earthflows (several are more than 3km in length), rock falls and debris flows, and these play a prominent role in shaping this landscape. More than 80 large mass movements have been identified with a combined footprint of >30 km2.

The area is developing rapidly, going through major expansions of urban communities and infrastructure networks. To achieve long-term sustainable development, it is urgently needed to identify the spatial and temporal patterns of multiple, and often interacting geohazards. This requires capturing landscape evolution processes and mapping of variations in mass balances of landslide, fluvial and erosion processes as these are influenced by tectonic activity and climate. In turn, this should enable assessment of how these processes interact with human interventions in this landscape.

The project aims to:

  1. Disentangle the complex web of interactions between exogenic dynamic processes and local lithotype properties that shape landforms by developing a physically-based numerical geomorphological model considering landslide activity (i), fluvial dynamics (ii), soil erosion (iii), tectonic processes (iv), climate factors (v) and their spatio-temporal interactions.
  2. Assess the current and future multi-geohazard risk and possible interactions between landslides (rock falls, debris flows, slides) with fluvial processes (floods, incision/erosion) under a range of scenarios that reflect changes in climate and regional (societal) development.

 

 

Figure 1: Geological overview map of the Zhouqu region and landslides distribution. 1) River; 2) Faults; 3) Earthflows; 4) other landslides; 5) Quaternary deposits (gravels and sands in the river valleys, silts and clays mainly on valley shoulders); 6) Triassic and Jurassic conglomerates, mudstones, siltstones and shales; 7) Carboniferous and Permian limestones, dolomites and intercalated phyllites, slates and shale; 8) Devonian slates and phyllites; 9) Silurian phyllites, sandy slates, sandstones and intercalated limestones; modified from Zhang et al., 2018 (a). The Zhouqu debris flows of 8 August 2010 after cessation; image from WorldView-2 © 2010 by DigitalGlobe (b).

Methodology

The Z-BRB area represents a fascinating natural laboratory featuring different types of landslides with dimensions and rates of movement spanning many orders of magnitude. Through literature review and local fieldwork, the student will be able to gain impressions of the scale of the earth surface processes. Close collaboration with Lanzhou University and the Wudu Geohazards Emergency Response Centre will ensure relevance to regional geohazard risk management and sustainable development and end-user uptake of research findings. The assessment of geological-hydrological risk in the area requires expansion of a geomorphological transport model (cf. Xia and Liang, 2018) that will account for complex topography and factors such as heterogeneous lithological settings, landslide activity, fluvial dynamics, soil erosion and that can be used to run scenarios of changes in tectonic activity, climate and regional development.

 

Training and Skills

This project requires a student with an aptitude for computer-based process modelling and a good understanding of earth surface processes. For further development of key skills, the student will be able to benefit from courses at the British Geological Survey (e.g. analysis, processing and interpretation of satellite imagery through GIS software; developing programming skills for process modelling), NERC Advanced Training Short Courses in topics such as numerical modelling in Earth Sciences and understanding uncertainty in environmental modelling, and courses/fieldwork training through Lanzhou University.

Timeline

Year 1: Literature review of the current limitation and constraints of geomorphic transport laws. Fieldwork 1 will be considered at the beginning of the first year to fully understand the geomorphological processes in place. It will also help with the collection of the geomorphological and landslide data (including GPS trails of landslide markers, rain gauge information, stratigraphic columns and inclinometric measurements). High-resolution (<5 m in spacing) optical satellite imagery will be acquired, processed and interpreted at this stage. Ortho-rectified satellite images will be used for landslide and vegetation mapping with evaluation of source area characteristics, horizontal runout distance of the failed masses, involved volume, mobility and connectivity of slope debris with the river system.

A Digital Elevation Model (DEM) at <2 m resolution will be extracted from stereo satellite images so that morphometric parameters (e.g., vertical offset of scarps) can be extracted for identifying neo-tectonic structures and estimate tectonic rates of movements. These tasks will assess the magnitude of sediment influx and efflux and current rates of material accumulation and erosion in the area and will be mainly conducted at BGS under the supervision of Dr Novellino.

Year 2: Develop a physically based model to characterize the landscape evolution and consistent with the findings of the previous task. A general geomorphological transport model will be derived and implemented in the horizontally two-dimensional depth-average model (cf. Xia and Liang 2018 for flow-like landslides at a basin scale). This model will be connected with other slope and hydrological process models to take into account multi-hazard and cascading hazard scenarios (such as flooding connected to landslide dams or the effects of rock fall dams on flow velocity and mobility). This part will be developed at the Loughborough University/Lanzhou University. This is likely to result in the submission of a peer-reviewed journal article on this modelling phase at the end of the 2nd year.

Year 3: Assessment of geohazard risk: The relationships between the geomorphological and hydrological processes are required to better understand drivers of landscape evolution. Using satellite imagery and knowledge from the Wudu Geohazards Emergency Response Centre the vulnerability of the exposed elements at risk can be mapped (and scenarios of future development can be formulated). These components will be integrated into a risk assessment framework to assess the multiple geohazard risk management implications in the study area in the short and long-term (2030s, 2050s, 2070s). This is likely to result in the submission of a peer-reviewed journal article at the end of the 3rd year.

 

Partners and collaboration (including CASE)

This research will involve close collaboration of Loughborough University/British Geological Survey (BGS) with Lanzhou University and the Geohazards Emergency Response Centre in Wudu (Gansu, China) who form the likely end-users of the research. The external supervisor Prof Meng Xingmin has guaranteed support for local fieldwork and research activities. The student is expected to spend substantial time the field study region (Bailong Corridor centred around Zhouqu), at Lanzhou University and at the BGS. Fieldwork scheduling for this project is flexible and will be arranged to fit around the CENTA2 training requirements.

Further Details

For further information, please contact Dr Tom Dijkstra (t.a.dijkstra@lboro.ac.uk), Prof Qiuhua Liang (q.liang@lboro.ac.uk) or Dr Alessandro Novellino (alessn@bgs.ac.uk). For enquiries about the application process, please contact Berkeley Young (b.k.d.young@lboro.ac.uk), School of Civil and Building Engineering, Loughborough University. Please quote CENTA18-LU11 when completing the application form: http://www.lboro.ac.uk/study/apply/research/.