West Penwith Ecohydrological Investigation and Characterisation – Site Visit Report (Phase 3, 2020-21) (NECR402)

Land within Penwith Moors, Cornwall, is being considered for designation as a Site of Special Scientific Interest (SSSI) under the Wildlife and Countryside Act 1981. Valley mires are features of interest and 11 key valley mires (wetlands) have been identified for designation. In 2020 Natural England commissioned Atkins to undertake a catchment-based approach to identify all land that may influence the ecohydrology of the mires, and to determine which areas have the most significant influence. Using open-source data, that exercise identified ‘hydrological risk zones’ and associated ‘surface flow pathways’ within those catchments. In 2021, Natural England commissioned Atkins to undertake field visits of all 11 valley mire sites being considered for inclusion in the SSSI to verify the findings of the desk-study, in particular: to confirm farm and/or field scale hydrology mapped in the desk-study using open-source GIS and other data, especially with regards to different hydrological risk zones; identify field evidence of areas of groundwater exfiltration and flow pathways; and to collect local knowledge, where possible, through discussions with local landowners and land managers to understand drainage history and how it currently affects the hydrology of the West Penwith mires. The field visits were undertaken in May 2021 and verified the findings of the desk-study with some local amendments. This report should be read in conjunction with West Penwith Ecohydrological Investigation and Characterisation, Phase 3, 2020-21.