Regional assessment of the resilience of water supplies and environmental resilience

This CASE project will be supported by Thames Water

Background

There is growing concern about the resilience of water supplies in England, given the pressures of population growth, climate change, water quality challenges, different spatial stress patterns and the more extreme transitory nature of changes that the supply systems have to cope with. There is also concern about the sustainability and resilience of ecosystems that inhabit rivers and wetlands. These pressures are particularly acute in the South East of England which is highly populated, is less well endowed with water resources than some other parts of the country and is home to precious aquatic environments including chalk streams.  

To address these challenges, government, regulators and water companies have adopted a regional approach to water resource planning, which recognises the need for a broad-scale systems approach including the inter-dependence between neighbouring water companies. The approach is most developed in the South East and East of England, where pressures on water resources are most acute. Water Resources South East (WRSE) is an alliance of the six water companies that cover the South East region of England which is developing a collaborative, regional approach to managing water resources. The WRSE regional resilience plan will be used as a blueprint for water supply investment by each water company in the region.

Key Questions

WRSE and its constituent companies, including Thames Water, have already been responsible for research and innovation in pursuit of their resilience objectives, including through previous research projects in the University of Oxford. Furthermore, the University of Oxford has developed a national water resource system model, which includes the WRSE region, as well as more detailed models of the Thames catchment. There is already, therefore, a strong basis for further research. Several pressing research questions remain:  

1. Groundwater response to water withdrawals and climatic conditions. Groundwater in the region is well-studied, but the dynamics of groundwater response are still not properly included in water resource system models. This is critical in a region where water supplies and surface water environments are so dependent on groundwater. We propose to use a combination of the new groundwater model developed in the HydroJULES project and a simpler empirical method based on borehole measurements to develop an intermediate complexity fully coupled groundwater model, potentially suitable for inclusion in WRSE simulation modelling.  

2. Ecosystem resilience. Sensitivity of the aquatic environment to altered flow and groundwater regimes is not fully understood. We know that water bodies in a healthy condition are more able to recover from occasional shocks like droughts. There are more opportunities for enhancing ecosystems, for example through constructed wetlands, but whilst there have been many studies of restoration projects, the evidence base is difficult to generalize. We propose to develop an approach based on statistical analysis of ecosystem response to water levels and flow conditions, which fully incorporates uncertainties as the basis for an ‘adaptive management’ approach to enhancing ecosystem resilience, working with WRSE to embed thinking and methods into their options appraisal, impact mitigation and investment planning.  

3. Water quality responses to land use changes and farming practices. Build on the research previously undertaken by Oxford and other research institutions which derive a series of relationships or simple models that can simulate the impact of climatic events, different crops or farming practices on the raw water quality within catchments and the consequences this could have on the availability of water in the future. This module would be incorporated into the regional simulation model. 

4. The next generation of regional simulation and investment modelling. The new understanding of groundwater behaviour and ecosystem resilience will be incorporated in a regional water resource systems model driven by regional synthetic rainfall and climate conditions. The research will demonstrate how a regional simulation approach can be used to test and optimize investments and policies for water resources management and explore trade-offs between different users of water including the aquatic environment.  Research will also explore uses of simulation modelling beyond ‘tradition’ water resources planning metrics to inform and guide future policy development. 

5. Exploring dynamic intra- and inter-regional transfers. Transfers between companies within WRSE and between WRSE and other regions have the potential to provide significant benefits, making more efficient use of resources that are already available. Currently, such transfers are considered in a relatively simplistic manner, often as fixed ‘bulk supplies’. This research will explore how transfers could be optimised to bring about a more integrated water supply system across the South East, and how such an integrated scheme could be considered within existing water resources planning frameworks, as well as using new simulation and investment modelling methods developed in this research.

Aims of the Project

The research will involve a combination of statistical analysis (of groundwater and ecology) and hydrological modelling (of groundwater and surface water systems).  

Specialised skills required

The project will suit students from any quantified background, including engineering, economics, physical and environmental sciences. Students should be able to demonstrate aptitude for computer modelling and enthusiasm to address real-world problems of great policy significance. 

References 

Borgomeo, E. Mortazavi-Naeini, M., O'Sullivan, M.J., Hall, J.W. and Watson, T. Trading-off tolerable risk with climate change adaptation costs in water supply systems. Water Resources Research, 52(2) (2016). DOI: 10.1002/2015WR018164. 

Borgomeo, E., Pflug, G., Hall, J.W. and Hochrainer-Stigler, S., Assessing water resource system vulnerability to unprecedented hydrological drought using copulas to characterize drought duration and deficit, Water Resources Research, 51 (2015), 8927-8948. doi:10.1002/2015WR017324. 

Borgomeo, E., Hall, J.W., Fung, F., Watts, G., Colquhoun, K. and Lambert, C. Risk based water resources planning, incorporating probabilistic non-stationary climate uncertainties. Water Resources Research, 50 (2014): 6850-6873. 

Lake, P.S. 2003. Ecological effects of perturbation by drought in flowing waters. Freshwater Biology, 48(7), pp.1161-1172. 

Poff, N.L. et al. Sustainable water management under future uncertainty with eco-engineering decision scaling. Nature Clim. Change 6, 25-34, doi:10.1038/nclimate2765 (2016). 

Please contact Jim Hall on jim.hall@eci.ox.ac.uk  if you are interested in this project