Fully funded studentship: Developing Ecologically acceptable fine sediment targets for chalk rivers

Fine sediment accumulation in the gravel beds of chalk streams is a key reason for failure under the Water Framework and Habitats Directives, impacting salmonid spawning success, macro-invertebrate and macrophyte communities (richness and abundance). Excessive fine sediment accumulation is also believed to increase flood risk; and intuitively is a loss of critical natural capital to agricultural systems. This consequently results in significant expenditure on actions to reduce fine sediments loads.

Despite this, there remains considerable uncertainty around the actual targets for fine sediment accumulation in chalk gravel beds – how much is too much? Historic river water quality standards which focussed upon suspended sediment have been abandoned but not replaced, leaving a gap in the regulatory framework by which to gauge site/ecological condition and hence drive resources and efforts to regulate or influence activities that are sources of excessive fine sediment. In part this relates to a poor understanding of the ecological impacts of fine sediments in chalkstreams, as well a lack of fundamental understanding of the natural variability of fine sediment accumulation; and the local sources of fine sediment.

This research will utilise field and laboratory analysis in conjunction with numerical modelling to define ecologically acceptable targets for chalk streams, with a focus on the River Itchen, Meon and Test, in Hampshire. The student will work closely with local stakeholders to quantify the research challenge and work with leading academics in this field to develop the science to better inform the setting of sediment targets.

This research will complement on-going research o which includes development of a Sediment-sensitive Invertebrate (PSI) index, methods to identify sediment sources and Natural Flood management effectiveness as well as broader research on the role of sediments as vectors for macronutrients such as Phosphorous. Thus the research provides excellent opportunities to work alongside other researchers and stakeholders, and to gain wider experience of science-based river ecosystem management.

Candidates are expected to have a 2:1 in Geography, Environmental Science, Earth Science or other discipline in which your experience is relevant to understanding sedimentation processes and ecology.