This dataset includes weekly data from monitoring of stream, rainfall and groundwater hydrochemistry in the Vyrnwy research catchment between 1994 and 2001. Data for over 50 chemical determinands are presented alongside data for some in-situ measurements such as water temperature. Full descriptions of the analytical methods used for each determinand is included. Intensive and long-term monitoring within the catchments underpins a wealth of hydrological and hydro-chemical research; other linked datasets include river flow, meteorology and a variety of detailed spatial datasets representing the topography, soils and rivers of the catchments. Monitoring is funded by the Centre for Ecology & Hydrology. Full details about this dataset can be found at https://doi.org/10.5285/68f4a12f-740d-4705-9c27-6a7fb7127046

Surface water quality data for the Conwy catchment, North Wales are presented. The data cover stream and estuary survey locations sampled manually from 2007 to 2011 at varying intervals between fortnightly and quarterly. Survey locations were selected as draining the main landscape classes in the catchment, which include upland (>300m) and lowland (<300m) environments under trees, moorland or improved agriculture. Also included are a suite of locations on the major rivers, and in the estuary. The purpose of the data is to provide support for estimating loads and testing hypotheses relating to the relationship between subcatchment properties and water quality, and the relative importance of mixing and in-stream processes in influencing downstream water quality. Streams draining peat, with high dissolved organic carbon concentrations, are well represented. Upland drainage is generally acidic, and lowland circum-neutral. The lowland rivers are not heavily contaminated with nutrients, although they show evidence of some loss of nitrates in particular. There is little industry in the catchment beyond agriculture and tourism, though there is some legacy contamination from metal mines in a small part of the catchment. Measurements are provided for major cations and anions, pH, alkalinity, DOC, Al, Fe and conductivity for most samples, with values for a wide range of trace elements for a limited number of samples. Full details about this dataset can be found at https://doi.org/10.5285/c53a1f93-f64c-4d84-82a7-44038a394c59

This dataset includes rainfall, cloud, river and stream hydro-chemistry of the Plynlimon research catchments. The data is from weekly monitoring of stream hydrochemistry of the River Hafren (Severn) at both the Lower and Upper Hafren site from 1998, stream hydrochemistry of the River Hore at the Lower Hore site from 1983 and Upper Hore site from 1984 as well as rainfall hydrochemistry near the Carreg Wen meteorological site from 1983 and cloud hydrochemistry near the Carreg Wen meteorological site from 1990. Data for over 50 chemical determinands are presented alongside data for some in-situ measurements such as water temperature. Full descriptions of the analytical methods used for each determinand is included. The Plynlimon research catchments lie within the headwaters of the River Severn and the River Wye in the uplands of mid-Wales. Intensive and long-term monitoring within the catchments underpins a wealth of hydrological and hydro-chemical research; other linked datasets include river flow, meteorology and a variety of detailed spatial datasets representing the topography, soils and rivers of the catchments. Monitoring is funded by the Centre for Ecology & Hydrology, and is ongoing since 1968. Full details about this dataset can be found at https://doi.org/10.5285/44095e17-43b0-45d4-a781-aab4f72da025

Digital river network of the natural and artificial streams and rivers within the Plynlimon catchments.

These catchment boundaries define upland catchments and subcatchments at the headwaters of rivers Upper Hafren (Severn) and Upper Gwy (Wye). They identify the area of study of the Plynlimon research catchment project.

Distribution of soil parent materials in the Severn and Wye catchments. These were mapped during the Soil Hydrology Study conducted by JP Bell in 1968-1969: Bell, J.P. (1969). The Soil Hydrology of the Plynlimon Catchments. Institute of Hydrology Report No. 8, Institute of Hydrology, Wallingford, UK.

Elevation contour lines within the Wye catchment at 10 and 20 metre intervals. The contour lines have been digitised from a scanned topographic map.

Elevation contour lines within the Severn catchment at 10 metre intervals. Digitised from the scanned topographic maps.

Spot heights (elevation values in metres) for areas within the Plynlimon catchments; digitised from scanned topographic maps of Plynlimon Catchment Areas.

Hydrologically corrected digital terrain model (DTM) of Plynlimon catchments. The DTM was derived from digitised elevation data from scanned topographic maps.