The geomorphology of sandy braided rivers

Overview:
Understanding how changes to river flow regime, will shape the morphodynamic response of the World’s rivers is a major problem facing the global population. With large flood events predicted to become more frequent the associated socio-economic impacts relating to loss of land and damage to infrastructure are set to increase. However, there is a dearth of empirical data from such events that can be used to understand how rivers may respond. Based on ongoing NERC funded projects dating back to 2000 datasets already exist in the form of digital imagery with which to generate such data, albeit they remain to be fully analysed. By generating high-quality DEMs from imagery (e.g. Lane et al., 2010) this project will seek to develop important new insights into braided river morphodynamics as well as ideas such as self-organized criticality that has widespread relevance for landscape evolution more generally. Furthermore, the unique dataset that will be generated will allow basic questions such as ‘what is a braided river?’ to be properly quantified for the first time. While the bulk of the project will relate to the geomorphological analysis of braided river evolution via the DEMs, the project also aims to compare some of the DEM analysis with the morphodynamic model HSTAR (Nicholas et al. 2013) to help establish generic and objective tools for the validation of all such models. The output from this project is thus both fundamental and far-reaching in its scope.

Methodology:
The student will use an archive of imagery collected over a 10 km reach on the sandy braided South Saskatchewan River, Canada over the period 2003-2011. Following the methods outlined in Lane et al. (2010) and Parker et al. (2013) DEMs will be constructed for all these differing epochs, to provide a powerful database with which to then evaluate fully a range of scaling and numerical issues. For example, to properly investigate scaling relationships requires comparison of smaller sections of the braidplain (i.e. sub-km) with larger reaches, having a 10 km long DEM will allow us to do this. Similarly, when considering temporal scaling relationships morphodynamic evolution over short periods needs to be compared with that over longer time scales. The new DEMs to be constructed as part of this project will allow comparison of change over periods from 1 month up to 8 years. Classical concepts relating to magnitude-frequency can also be assessed by comparing river response in relation to contrasting flow events.

Training and skills:
CENTA students will attend 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student’s projects and themes.
This project would ideally suit a student with interests in fluvial geomorphology and high-level skills in GIS techniques. Depending on the skills of the student training can be provided, however, it is expected the student will have likely completed GIS based analysis as part of their undergraduate or Masters projects, for example.

Partners and collaboration:
This project also benefits from being closely linked with a large 3 year NERC project ‘Modelling how sediment suspension controls the morphology and evolution of sand-bed rivers’. The successful candidate will thus benefit from being part of a large, supra-disciplinary, international research team with the possibility of also collaborating with colleagues at the Universities of Illinois. If interested there would also be an opportunity for the student to gain additional experience by undertaking fieldwork in Canada as part of the wider NERC funded project on the South Saskatchewan River, Canada.