Analysis of the quality and completeness of UK river flow data - a long-term view

Globally, access to hydrometric data with sufficient record length, quality, and geographical coverage to address research questions and manage freshwater systems remains a significant challenge. The UK National River Flow Archive (NRFA) oversees river flow data from over 1,600 locations across the UK. Data from almost 1,000 stations are acquired and displayed as ‘provisional’ in real-time, while the NRFA conducts a comprehensive update to the quality-controlled dataset annually. Upon submission, river flow records undergo both automated data screening and manual quality control by trained hydrologists to ensure the highest quality data are disseminated to the Archive’s broad user community, making it fit-for-purpose for various applications.

In the 1990s, increasing gaps in river flow records and declining data quality led to the introduction of a Service Level Agreement (SLA) in 2002, to safeguard the UK’s hydrometric network and its data. This paper presents the results from 20 years of applying the SLA system, analysing a set of quantifiable indicators of data quality, completeness and provision. The observed improvements underscore the advantages of the SLA in enhancing the reliability of the nationally archived river flow data. Furthermore, it serves as a model for quality assurance and performance measurement systems that can be adopted as best practice by other monitoring networks globally. These results also demonstrate a method of helping to ensure hydrological databases provide high-quality information to meet current and future research and water management needs.