The data consists of a matrix of twelve land cover classes by 20 stream sites with the area of each land cover class given in km^2. The areal coverage (km2) of each of twelve land cover classes was recorded for each of 20 chalkstream catchments in southern England. The 20 discrete chalkstream catchments are distributed along the white chalk geology extending from Dorset in the south west, through Wiltshire, to Hampshire in the north east, to cover a gradient of catchment land cover intensification from extensive calcareous grassland and woodland through to arable and improved grasslands. These data were acquired in July 2012. This dataset was created as part of work package 3.1 of the Wessex Biodiversity & Ecosystem Service Sustainability (BESS) project. Full details about this dataset can be found at https://doi.org/10.5285/b8a66584-da67-49e5-a0b0-d8e0b3e75b99