River water alkalinity, chloride-ion, conductivity, pH and nutrients data from the Frome Piddle; Pang Lambourn and Tern catchments, recorded between 2003 and 2006. River water samples were collected fortnightly at twenty three sites within these catchments and analysed for Alkalinity pH 4.5, Ammonia, Chloride-ion, Conductivity 20 deg C, Nitrate, pH, Phosphorus soluble reactive (SRP), Silicate reactive dissolved (SRD) and Sulphate. The samples were collected as part of the NERC funded Lowland Catchment Research (LOCAR) Programme to provide comparable baseline river water chemistry data across the LOCAR catchments. Full details about this dataset can be found at https://doi.org/10.5285/bb600a56-c9cf-4fca-b9be-be3de0039a79

Data consist of modelled estimates of observed/expected Biological Monitoring Working Party (an index for measuring the biological quality of rivers using selected families of macroinvertebrates as biological indicators) scores for freshwater streams across Great Britain (GB). The BMWP scores (1-10) are based on the principle that macroinvertebrates differ in their perceived sensitivity or tolerance to organic pollution (i.e. nutrient enrichment). Values greater than 1 indicate high water quality. Data pooled across two survey years (1998 and 2007) was used to model the relationships between headwater stream quality and catchment/stream characteristics for headwater streams across GB based on known relationships for headwater streams in Countryside Survey squares. Modelled estimates of stream water quality were based on a Boosted Regression Tree modelling approach . Full details about this dataset can be found at https://doi.org/10.5285/85e7beb6-e031-4397-a090-841b8c907d1b

[This dataset is embargoed until March 31, 2023]. This dataset contains high-resolution (5-minute) discharge, turbidity, suspended sediment concentration, and total phosphorus concentration data measured at three stream sites in the Littlestock Brook catchment (a tributary of the River Evenlode) from 2017 to 2021. The turbidity and concentration data were derived from a combination of instream sensors and lab-analysed water samples. Discharge data were derived using a stage-discharge rating curve constructed from manual measurements of flow velocity and water level sensor measurements. This dataset was collected by UKCEH as part of a hydrological monitoring programme for the Littlestock Brook Natural Flood Management scheme. There are some periods of data gaps within the timeseries as a result of sensor errors which have been excluded. These data may be used to calculate suspended sediment and phosphorus fluxes loads leaving the catchment. This work was supported by the Natural Environment Research Council (Grant NE/L002531/1). Full details about this dataset can be found at https://doi.org/10.5285/9f80e349-0594-4ae1-bff3-b055638569f8

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

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 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

Water quality data produced from rainfall, throughfall and stemflow samples collected within a beech stand at Black Wood in Hampshire, and an ash stand at Old Pond Close in Northamptonshire. Two studies were carried out in the early 1990s to examine water quality in relation to hydrological and pollution changes. Chemical analysis involved a combination of electrometric (pH), inductively-coupled plasma emission spectroscopy (most major, minor and trace elements), atomic absorption spectroscopy (potassium), ion chromatography (major anions and fluorine) and colourimetry (ammonium and silicon).

Discrete total alkalinity data for 13 sites in the Humber catchment sampled within the period 1993 to 1997 and 1996 to 1997 and for 3 sites from the Tweed catchment over the period 1994 to 1997, as part of the Land Ocean Interaction Study project (LOIS). Sites were sampled at regular weekly intervals and more intermittently during high flows (on average an extra sampling once a month per site). Samples were analysed on day of collection or on arrival at the laboratory using a Metrohm 702 Titrino autosampler. Full details about this dataset can be found at https://doi.org/10.5285/73a7ae36-2882-434f-a206-76b848e22d82

Adventdalen is a medium-sized (513 km^2) catchment in continuous permafrost zone of central Spitsbergen. It has 11.7 % glacier cover, a large flat valley floor comprised of uplifted, glaciomarine sediments, covered in the lower part by a veneer of aeolian sediments up to 4 m thick. The geology of the catchment is dominated by sandstones, shales and carbonates. There are a series of five open system pingos that have formed in the valley floor following uplift of the valley bottom over the last 10000 years. This has caused permafrost aggradation in former marine sediments which are up to 60 m thick. During the formation of this new permafrost, high pressure caused expulsion of groundwaters below, resulting in their upward migration. Freezing of the groundwaters as they reached the ground surface caused expansion and thus formation of the pingo. However, freezing no longer occurs at four of the five pingos, meaning that the groundwaters now discharge at the surface. Samples of the emerging groundwaters were collected every March/April, but also opportunistically during summer months, provided the sites weren''t flooded. Analysis of major ions (by ion chromatography), minor constituents (trace metals by inductively coupled plasma mass spectroscopy (ICP-MS) and silica by colorimetric analysis) and gases (O2, CO2 and CH4) were undertaken. Funding was provided by the Joint Programming Initiative (JPI-Climate Topic 2: Russian Arctic and Boreal Systems) Award No. 71126, distributed to Principal Investigator, Andrew Hodson (then of University of Sheffield) via NERC grant NE/M019829/1.

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.