Quantifying risks to microbial water quality in Guizhou province and the South West China karst region

In rapidly-developing countries such as China, there is high vulnerability to climate change impacts on water supply and quality. Understanding the fate and transfer of pathogens and their pathways of exposure to human populations is therefore important in areas of China where water sources are vulnerable and prone to contamination, e.g. karst landscapes. This risk may be further compounded by the highly transmissive nature of the karst, with fast channel flow resulting in rapid contamination of drinking water aquifers and recycling of contaminated water onto food crops through abstraction and irrigation practices.

From 2016-2018, a large multi-partner NERC-NSFC funded project undertook an integrated assessment of hydrology and water quality in the Houzhai catchment to identify strategies to sustain the ecosystem services of karst landscapes under increasing land use change pressures and to build resilience to climatic change in the SW-China karst region. Data on nutrient export from the catchment was complemented with microbial water quality monitoring as part of an IAPETUS PhD now nearing completion. An opportunity now exists to further develop our understanding of microbial risks to water quality in this sensitive landscape of the SW-China karst region through the use of models of hydrological connectivity (such as SCIMAP) and landscape E. coli loading (ViPER), and the newly developed SCIMAP-FIO, which linked SCIMAP & ViPER to extend the capability of SCIMAP to enable assessment of the microbial risk to water quality by faecal indicator organisms (FIOs), e.g. E. coli. This studentship will therefore build on our new understanding of this catchment and develop a spatial modelling approach to couple with and extend previous fieldwork campaigns. Members of the supervisory team are now involved in a 2nd phase of follow-on funding in China that is exploring the development of decision support tools for environmental management, which would further complement this PhD.

Research objectives: The overall aim of this studentship is to provide critical advances in hillslope to catchment scale modelling of E. coli delivery from land to water in typical cone & depression karst landscapes of SW China. The student will address the following research objectives:

1. Identify challenges and opportunities for translating existing modelling capability to the karst landscape of the Houzhai catchment;
2. Derive E. coli die-off values relevant for organic wastes and livestock typical of the Chinese karst terrain;
3. Parameterise, test & verify the ViPER model of E. coli loading to land at plot to subcatchment scales using newly derived die-off coefficients;
4. Adapt and deploy SCIMAP-FIO to model spatial and temporal risks to microbial water quality across the Houzhai catchment and ground-truth outputs at multiple scales.

Fieldwork and modelling will be carried out in the SW-China karst terrain. Guizhou province is in the centre of the SW karst terrain and is the location of the primary field site, the Houzhai Catchment (81 km2, nested within Sancha river basin, 5542 km2). A programme of field work in China will focus on how different land uses and hydrological drivers impact on microbial fate & transfer in the karst terrain. The student will link on-the-ground data collection and experimental results with modelling efforts to explore how land use and seasonality influences FIO source loading and subsequent transfer from land to water. Modelling will be driven by two existing platforms, but will be modified to reflect the local and challenging conditions typical of the Houzhai catchment: (1) SCIMAP - a risk-mapping tool designed to identify the origins of diffuse pollutants in the landscape through combined assessment of spatial patterns of source risks with hydrological connectivity; (2) ViPER – a model to map spatial patterns of E. coli accumulation on land.

This studentship will provide a platform to build an interdisciplinary research career in applied microbiology and hydrology in the context of diffuse pollution with human health impact. Extensive skill development in fieldwork will include comprehensive training in sampling & monitoring techniques, while the student will also benefit from working closely with experienced field researchers in China during field campaigns.