Long-term low-frequency or short-term high-frequency monitoring: are both necessary?

Sarah Halliday, Andrew Wade, Colin Neal, Brian Reynolds, David Norris, Richard Skeffington

Research output: Chapter in Book/Report/Conference proceedingConference contribution


This paper describes the patterns observed in a high-frequency (7-hourly) streamwater chemistry data set obtained
for the Plynlimon Catchment, Wales from 2007-2009. Plynlimon is an upland site underlain by lower Palaeozoic
mudstones, greywackes and sandstones that are overlain by thin acidic soils comprised mainly of stagnopodzols
and peats. Vegetation cover is dominated by acid grassland (Nardus-Festuca) and heath land with plantation
forestry in the lower parts of the catchment (mainly Sitka spruce Picea sitchensis). The site has a long history of
environmental monitoring which started in earnest in the early 1980s and continues to the present day to look at the
issues of evapotranspiration from coniferous forest and the impacts of clear felling and acid deposition on soil and
streamwater quality. The new dataset is explored using time-series analysis and this talk will focus on a sub-set of
determinands including pH, aluminium, chloride, nitrate, calcium, sulphate, silicon, DOC, iron and conductivity.
The results are compared with a longer-term (1983-2010) hydrochemical dataset from the same study area which
was sampled at lower frequency (weekly). This comparison provides an opportunity to assess the value and information
content of both long-term, low frequency and short-term, high-frequency datasets. The results will be
discussed in terms of the catchment hydrological and hydrochemical processes operating at different spatial and
temporal scales. The discussion will also focus on the information content of high-frequency water quality data
versus the cost of collection.
Original languageUndefined/Unknown
Title of host publicationEGU General Assembly 2011
Publication statusPublished - 2011
EventEGU General Assembly 2011 - Austria Center, Bruno-Kreisky -Platz, Vienna, Austria
Duration: 3 Apr 20118 Apr 2011


ConferenceEGU General Assembly 2011
Abbreviated titleEGU2011
Internet address

Cite this