Forecasting contamination events affecting Chalk water quality using time-series analysis


   Faculty of Environment

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  Dr Jared West, Prof S Bottrell  No more applications being accepted  Competition Funded PhD Project (Students Worldwide)

About the Project

We invite applications for a fully funded EPSRC PhD studentship to work on an opportunity for investigating the impacts of contaminants on water quality in the Chalk catchments of SE England. This research will exploit a unique and timely opportunity for forecasting the occurrence of contamination events affecting groundwater and groundwater-fed Chalk streams. This project will entail an improved understanding of the impact of catchment characteristics on contamination risks to receptors including groundwater abstractions, chalk stream ecosystems and bathing waters, to allow preventive and restorative actions to be taken. Key highlights are as follows:

- Opportunity for investigating the impacts of contaminants on water quality and quantity.

- Investigation of one of the world’s most important aquifers, the Cretaceous Chalk.

- Determination of karst extent in chalk, to better understand its development, and identify the impact of rapid karstic flow processes on water quality.

- Identification of preventive actions to be taken Water Companies to facilitate improved future groundwater and surface water resource management and protection.

It is anticipated that this project will have a tangible impact on risk management strategies for Chalk catchments. The outputs of this research will be used for decision making by stakeholders in the UK such as Water Companies and the Environment Agency but also more widely. By conducting fieldwork (e.g., abstraction and stream sampling/lab fluorescence analysis plus deployment of in situ fluorescence loggers) and correlation analysis of data with rainfall, you will develop new analytical tools and approaches for characterisation of specific pathways and contaminant impacts, as well as providing information on aspects of functioning the specific chalk catchments investigated. The outputs of this investigation will be transferrable to other catchment systems and constitute the basis of a new generation of risk management approaches for water quality.

Full description

Background

Chalk catchments represent the most important groundwater resource in the UK and are important ecologically because of their unique chalk stream ecosystems, and are crucial for public water supplies. Similar catchments exist in France, Belgium, Netherlands, and Denmark. Cryptosporidium and other pathogens threaten public water supplies and inland recreational water quality; particulates such as silt, micro-plastics such as tyre rubber and associated bound nutrients threaten river habitats; pesticides, pharmaceuticals, PFAS (‘forever chemicals’), hydrocarbons, heavy metals and dissolved nutrients threaten both public water supplies and river habitats. The relative importance of these threats to water quality depends on chalk catchment functioning, i.e. extent of development of karstic features (stream sinks, widened fractures and conduit development in chalk due to dissolution by groundwater flow) as well as the presence/absence of sources such as sewer outflows, specific farming activities and roads. Analysis of the temporal signals from water quality indicators such as turbidity (sediment load), electrical conductivity, and natural organic matter fluorescence may lead to improved understanding of catchment function. Such indicators have several advantages over artificially introduced tracer chemicals, including long-time series data at widespread locations from statutory monitoring of groundwater abstractions by water companies. Unlike for artificial tracers there is no need to a priori select injection points so the signals provide less biased indication of the entire catchment response. By considering the catchment as a system which transforms the input (rainfall) signal into the output signals (turbidity, conductivity, natural dissolved organic matter fluorescence), analysis of the time-series data can identify contaminant pathways and travel times facilitating risk assessments for specific contaminant groups.

Hypothesis

Proposed research will explore the extent that forecasting the occurrence of contamination events affecting Chalk groundwater, groundwater-fed streams, and public water supplies is possible using time-series analysis of rainfall versus naturally occurring indicators of water quality, such as turbidity, electrical conductivity and natural organic matter fluorescence. This project will aims to produce an improved understanding of the impact of catchment physical characteristics (land-use, geological factors, climatic variables, drainage infrastructure and waste-water discharges) on contamination risks to receptors including groundwater abstractions, stream ecosystems and bathing waters, to allow preventive and restorative actions to be taken. 

Aims and Objectives

1. Identify specific catchments with sufficiently long time series of water quality indicator datasets (water companies have been required to monitor abstraction for turbidly and EC by law since 2016).

2. Instrument catchments for additional sampling points (e.g. streams) and quality indicators e.g. natural fluorescence. Pre-process datasets for correlation and spectral analysis.

3. Undertake correlation analysis for input (rainfall) and output (turbidity, specific conductance, and fluorescence) signals – i.e. Fourier transformation, generation of Impulse Response Functions for cross-correlation and wavelet analysis to quantify memory effects and lag times. 

4. Geospatial analysis of Impulse Response Functions with respect to land-use, geological factors (presence/absence of sinking streams or other surface karst features, unsaturated zone thicknesses, superficial deposits), climatic variables, drainage infrastructure and wastewater discharges.

5. Identify extent to which Impulse Response Functions can predict risks from specific contaminant groups, by area specific comparison with reported water quality breaches in abstractions and streams

Chemistry (6) Environmental Sciences (13) Geography (17)

Funding Notes

There are two funded places (one home and one international) across all projects advertised in the EPSRC DTP. This means that not all projects will be recruited to- only two candidates will be successful and are selected on the basis of merit.
The award will cover the full fees (home or international) plus an annual maintenance stipend matching UKRI standard (£18,622 in 2023/24).

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