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 consists of headwater erosion process data for sites across Wales between 2021 and 2023, collected as part of the Environment and Rural Affairs Monitoring and Modelling Programme (ERAMMP) National Field Survey. Data include the classification and extent of erosion features. Headwater stream survey data was collected from 101 x 1km squares across Wales, collected as part of the Environment and Rural Affairs Monitoring and Modelling Programme (ERAMMP) National Field Survey. Erosion features were identified in 99 surveyed headwater streams. ERAMMP follows an earlier monitoring programme, the Glastir Monitoring and Evaluation Programme (GMEP), which was set up by the Welsh Government in 2013 to monitor the effects of the Glastir agri-environment scheme on the environment and ran from 2013 to 2016. The field survey element for both GMEP and ERAMMP was based on a stratified random sampling design of 300 x 1km square sites across Wales (225 of which were resurveyed for ERAMMP in 2021-23, though not all squares contained headwater streams). It was managed by the UK Centre for Ecology & Hydrology. Full details about this dataset can be found at https://doi.org/10.5285/6973d1b1-4814-4ff5-8daa-4d825ca3c4b9

This dataset consists of headwater quality data for sites across Wales between 2021 and 2023), collected as part of the Environment and Rural Affairs Monitoring and Modelling Programme (ERAMMP) National Field Survey. Data include water chemistry and ecological quality metrics, River Habitat Survey data (including information on substrates, flow types, aquatic vegetation, channel and bank materials, modifications and natural features, riparian land use, artificial features, spot check records, tree cover and associated features and Habitat Modification and Habitat Quality indices), macro-invertebrate taxonomic and abundance data, diatom taxonomic and abundance data, headwater quality indices derived from both the invertebrate and diatom communities and associated environmental data. Headwater streams were surveyed within a set of 101 x 1km squares across Wales, collected as part of the Environment and Rural Affairs Monitoring and Modelling Programme (ERAMMP) National Field Survey. ERAMMP follows an earlier monitoring programme, the Glastir Monitoring and Evaluation Programme (GMEP), which was set up by the Welsh Government in 2013 to monitor the effects of the Glastir agri-environment scheme on the environment and ran from 2013 to 2016. The field survey element for both GMEP and ERAMMP was based on a stratified random sampling design of 300 x 1km square sites across Wales (225 of which were resurveyed for ERAMMP in 2021-23, though not all squares contained headwater streams). It was managed by the UK Centre for Ecology & Hydrology. Full details about this dataset can be found at https://doi.org/10.5285/776f99f4-1506-4f7f-920f-8318561d4085