Upland sites have traditionally been exploited for livestock grazing, timber production and salmonid fisheries, but are also of high conservation and amenity value and important for water resources and carbon storage. In addition, as a result of high rainfall and low permeability soils, a disproportionate amount of floodwaters can be generated from upland catchments. Land use changes affect the overall catchment water balance by influencing evaporation rates.
The Plynlimon research catchments are two, almost identical, adjacent uplands catchments, with the exception that one is used for grazing sheep while the other is mostly under plantation conifer forestry. Intensive and long-term monitoring within the catchments underpins a wealth of hydrological and hydro-chemical research. The combined datasets include river flow, rainfall, cloud and stream hydro-chemistry, meteorology and a variety of detailed spatial datasets representing the topography, soils and rivers of the catchments.