The UK has one of the densest gauging station networks in the world – a necessary response to its diversity in terms of climate, geology, land use and patterns of water utilisation. This diversity and, particularly, the compelling impact of artificial influences on natural flow regimes across most of the country, implies a considerable challenge in identifying, interpreting and indexing changes in river flow regimes. Quantifying and interpreting trends in river flows – in particular separating climate-driven changes from those resulting from other driving mechanisms – is a necessary pre-requisite to the development of improved river and water management strategies. It is also a primary strategic objective of many national and international river flow monitoring programmes.
This paper charts the development of the UK Benchmark Network through its initial promotion phase – involving key institutional partners in both the hydrometric data acquisition and user communities – through to its exploitation across a wide a range of policy, scientific and engineering design applications. Particular consideration is given to the criteria used to appraise and select candidate catchments and gauging stations. Spatial characterisations (particularly physiographic, geological and land use) are used to determine the representativeness of individual candidate catchments and hydrometric performance (in the extreme flow ranges especially), together with record length, is of primary importance in relation to gauging station selection. Indexing the degree to which artificial influences disturb the natural flow regime is also a necessary pre-requisite for selection across much of the UK. Descriptions are given of a number of network and data review mechanisms developed to maximize the utility of the Benchmark Network and the burgeoning range of applications which have capitalized on it – embracing both national and international monitoring programmes.
The review finishes with an overview of the strategic benefits deriving from the operation of the Benchmark Network and examines some of the enduring issues which require further work – including the continuing focus on operationally driven gauging activities; meeting the more stringent data demands of the Benchmark Network, and the need for further integration of catchment monitoring activities – embracing a wider range of hydrometeorogical variables
