Science and research

UK Upland Waters Monitoring Network

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UK UWMN Science

Allt a'Mharcaidh

The UK Acid Waters Monitoring Network (now the UK Upland Waters Monitoring Network) was set up to provide crucial chemical and biological data on the extent and degree of surface water acidification in the UK uplands, in particular to underpin the science linking acid deposition to water quality and to monitor the response of aquatic ecosystems to reductions in air pollution. The sites making up the network were selected on the basis of acid deposition inputs being the only major sources of pollution, i.e. with no point sources of pollution or direct catchment disturbances other than traditional upland land use practices such as sheep grazing or forestry.

The water chemistry and biological data provided by the UK UWMN provide the highest quality datasets for the development and application of Critical Loads models which are used on a national basis for the provision of data for freshwater ecosystems under the UN-ECE Gothenburg Protocol. Likewise, they have been widely used in the development of dynamic acidification models such as the MAGIC Model which provides information on both the pre-industrial reference conditions of lakes and streams and predicts future responses to current or planned levels of acid deposition to determine the likely effectiveness of measures to reduce pollutant emissions.

Since its inception, the UK UWMN has been closely linked to the Defra research programme on the impacts of air pollutants on freshwater ecosystems, initially the Freshwaters sub-group of the Critical Loads of Acidity Group (CLAG) and subsequently the Critical Loads of Acidity and Metals (CLAM) and Freshwater Umbrella programmes.

The Network has evolved since its beginnings when the primary focus was to assess responses to reductions in sulphur deposition, through comparisons of high and low deposition sites across a gradient of sensitivity, encompassing rivers and lakes and comparing forested with moorland catchments. In 1995, following recognition of nitrogen (N) deposition as a key driver for surface water acidification, measurement of total dissolved nitrogen (TN) was added to the suite of chemical determinands collected (as was total dissolved phosphorus, TP). At the same time toxic metal concentrations were also identified as a potential problem and one of the UK UWMN sites in north east Scotland, Lochnagar, was set up to monitor mercury (Hg) in atmospheric deposition, water and aquatic plants. Climate change was also recognised as potentially a major driver of change at these sites; surface and deep water thermistors were installed at all lake sites in 1999, a weather station installed at Lochnagar in 2002 and an automatic hydro-meteorological monitoring buoy equipped with a thermistor chain and water quality sensors deployed at the Round Loch of Glenhead in 2005. A thermistor chain was installed at Llyn Llagi in 2010 and chains were added at all other lake sites in 2013. Installation of thermistors at stream sites started in 2010 and was completed in early 2015 with the addition of instruments at the three streams in Northern Ireland. However, several stream sites still lack instrumentation to measure flow continuously, while eight out of the eleven lake sites lack level recorders. Instrumenting the network to enable the potential future impact of climate change to be quantified is seen as a priority for the next stage in its development.

In addition to monitoring recovery from acidification, data from the UK UWMN are therefore central to ongoing research programmes on other drivers of change in upland catchments, including N Deposition and Eutrophication, Land Use Change and Climate Change.

Further detailed analysis of UK UWMN science can be found in the interpretative reports and Network scientific publications.

Page last modified: 24th July, 2015
Page published: 12 March 2010