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Non-stationary methods of flood frequency analysis are widespread in research but rarely implemented by practitioners. One reason may be that research papers on non-stationary statistical models tend to focus on model fitting rather than extracting the sort of results needed by designers and decision makers. It can be difficult to extract useful results from non-stationary models that include stochastic covariates for which the value in any future year is unknown. We explore the motivation for including such covariates, whether on their own or in addition to a covariate based on time. We set out a method for expressing the results of non-stationary models as an integrated flow estimate, which removes the dependence on the covariates. This can be defined either for a particular year or over a longer period of time. The methods are illustrated by application to a set of 375 river gauges across England and Wales. We find annual rainfall to be a useful covariate at many gauges, sometimes in conjunction with a time-based covariate. For estimating flood frequency in future conditions, we advocate exploring hybrid approaches that combine the best attributes of non-stationary statistical models and simulation models that can represent changes in climate and river catchments. [ABSTRACT FROM AUTHOR]

Flooding in 2021 has highlighted the increased risk to national resilience. This is against a backdrop of the UK climate projected to become more extreme over the next few decades. This paper considers the notable river and surface water flood events within England and Wales during 2021 and examines the performance of the Flood Forecasting Centre in highlighting the flood risk to our customers. We reflect on team debriefs as well as feedback and surveys from our customers. We distil our learnings and make connections with improvements in our underpinning science, forecasting tools, products and services. Finally, we highlight challenges associated with surface water flooding and suggest how we may collectively start to overcome these. [ABSTRACT FROM AUTHOR]

Flow estimates for ungauged catchments are often derived through regionalisation methods, which enable data transfer from a pool of hydrologically similar catchments with existing gauging stations (i.e., pooling-groups). This paper presents a methodology for indexing the utility of gauged catchments within widely used pooling-group methodologies for high and low flow estimation; this methodology is then used as the basis for a network evaluation strategy. The utility of monitoring stations is assessed using catchment properties and a parallel, but independent, appraisal of the quality of gauging station data, which considers hydrometric performance, anthropogenic disturbances and record length. Results from the application of the method to a national network of over 1,100 gauging stations in England and Wales are presented. First, the method is used to appraise the fitness for purpose of the network for regionalisation. The method is then used to identify gauges which monitor catchments with high potential for regionalisation, but which are deficient in terms of data quality - where upgrades in hydrometric performance would yield the greatest benefits. Finally, gauging stations with limited value for regionalisation, given the pooling group criteria employed, are identified. Alongside a wider review of other uses of the network, this analysis could inform a judicious approach to network rationalisation. [ABSTRACT FROM AUTHOR]

This paper aims to demonstrate that the regulation of drinking water quality in England and Wales has been successful in securing the improvements to drinking water quality resulting in better performance against EU and national standards. The water industry in England and Wales went through a major change in 1989 when suppliers were privatised and the government set up a robust regulatory regime. The regime was necessary as the industry was, as a result of privatisation, a monopoly with customers having no choice of supplier, unlike what was later available with other utilities such as gas or electricity. The regime would protect the interests of the consumer, the environment and public health through the quality of the product. The Drinking Water Inspectorate (DWI), as established in 1990, had to ensure the implementation of the European Drinking Water Directive (DWD) that had been transposed into national legislation. The aim of the DWD is to ensure that all EU Member States provide drinking water of a prescribed quality. In England and Wales, a body was required to oversee the performance of the industry against those standards, reporting to the Government and the European Commission. Through acts and legislation, the set up of the industry, the duties of the suppliers and regulators and the powers available to the regulators were established. The improvements to drinking water quality since privatisation were achieved by massive investment of the privatised water industry overseen by an independent regulator with clear duties and the powers to inspect, enforce and prosecute. The DWI's achievements show that to improve quality performance with the ability to report in detail how the improvements were made with extensive data evidence, a special regulator is required. The DWI advises policy departments and Ministers and when there are serious concerns regarding a threat to human health through drinking water, the highest level of regulatory power is the creation of new legislation, for example, the Cryptosporidium regulations that are unique to the UK. The DWI is more than what is traditionally thought of as a regulator because it has a single remit -- drinking water quality -- and its style of regulation has been key to improved drinking water quality in England and Wales. [ABSTRACT FROM AUTHOR]