Developing Ecologically acceptable 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, and 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 modelling to better 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 (Environment Agency, Natural England, Hampshire and IoWight Trust, Test and Itchen Catchment Partnership) 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.

Developing ecologically-based fine sediment targets bespoke to local chalkstreams will also inform advice on how best to reduce inputs, and manage flood risk. Hence there are potential synergies with local research into natural flood management in chalk catchments and land management, and soil-conservation practices. Work in the upper Itchen has shown there to be a close association between inputs of Phosphates, which themselves are a major cause for WFD and Habitats Regulations failures, and fine sediment, so this work will also dovetail with on-going work to understand the sources and effects of Phosphates in these chalkstreams.

We are looking for a motivated and skilled aquatic ecologist or environmental scientist / Physical Geographer, with experience of studying aquatic ecosystems and a determination to undertake high quality science for informing operational and strategic measures of managing river systems. If you have informal enquiries please contact any of the supervisors.

Academic requirements
2:1 in Ecology, Geography, Environmental Science, Earth Science or other discipline in which your experience is relevant to understanding sedimentation processes and ecology.


Provisional date for Interviews: 30 June 2019