Understanding catchment water quality: The potential of citizen science and low-cost monitoring approaches

Von Benzon, Elena 2025. Understanding catchment water quality: The potential of citizen science and low-cost monitoring approaches. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Water quality monitoring is essential for identifying, understanding and addressing river pollution. However, water quality can change rapidly across river catchments making achieving sufficient spatial and temporal coverage challenging. Citizen science, which relies on volunteers using low-cost methods, can help increase data coverage at a fraction of the cost of statutory monitoring approaches. However, the range of methods available are limited and the quality of data obtained is often not well understood, leading to a lack of trust among catchment managers. Despite providing increased temporal coverage compared to professional grab sampling programmes, citizen science approaches often fail to identify short-lived water quality events captured by continuous monitoring. This study aimed to: (i) quantify the data quality of widely used low-cost water quality tests; (ii) assess how increased spatial and temporal coverage enhances understanding of catchment water quality; (iii) develop and evaluate a novel low-cost sensor designed for citizen scientists; (iv) demonstrate how high-frequency data from low-cost sensors can be used to identify water quality issues. A combination of laboratory and field testing methods, supported by statistical analyses and surveys, demonstrated that several low-cost field tests widely used by citizen scientists (including the Hanna Phosphate Checker, HM Digital EC-3 and Hach nitrate test strips) produced good agreement with professional laboratory analysis of samples, despite limitations in their precision. Development of a novel wireless sensor (Hydrobean) and base station - designed to support citizen science grab sampling - was challenging but ultimately resulted in a robust device that provided acceptable agreement with commercial sensors. A modelling approach was applied to interpret high-frequency data from a test site in East Devon, piloting a method that used statistical analysis of specific conductivity and fixed-point river depth data to generate water quality ‘alerts’ when deviations from baseline conditions were detected. This thesis demonstrates that validated low-cost methods can provide valuable insights when used at scale by citizen scientists as part of coordinated monitoring efforts. It highlights the untapped potential of both volunteer monitoring programmes and low-cost sensor networks to enhance the temporal and spatial resolution of water quality data. These findings have wide-ranging implications that empower citizen scientists and support statutory monitoring efforts to improve current water quality monitoring approaches, providing value to governments, NGOs and local communities.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Earth and Environmental Sciences
Date of First Compliant Deposit:	6 November 2025
Last Modified:	07 Nov 2025 09:47
URI:	https://orca.cardiff.ac.uk/id/eprint/182185

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