Understanding geohazards in the UNESCO WHL site of the Derwent Valley Mills (UK) using geological and remote sensing data

An analysis of the British Geological Survey’s key hazard datasets (GeoSure, DiGMapGB, National Landslide Database, Geological Indicators of Flooding and Susceptibility to Groundwater Flooding) has provided an enhanced understanding of geohazards within the Core Area and Buffer Zone of the UNESCO Derwent Valley Mills World Heritage List (WHL) site, UK. This knowledge contributes to the preservation of this industrial heritage site that is included as the UK demonstration site of the Joint Programming Initiative on Cultural Heritage and Global Change (JPI-CH) Heritage Plus project PROTHEGO: ‘PROTection of European cultural HEritage from GeO-hazards’ which is mapping geohazards in the 400+ WHL sites of Europe using satellite radar interferometry (InSAR) combined with geological information. Acting as baseline geohazard characterisation to feed into PROTHEGO’s WP5-WP6, our analysis reveals that flooding from fluvial water flow and emergence of groundwater at the ground surface (across over 50% and 40% of the Core Area, respectively) are the main geohazards that require careful consideration, together with slope instability along the steep sides of the Derwent river valley (e.g. 1.4 km2 landslide deposits found at Cromford within the Buffer Zone). The UK Climate Projections 2009 (UKCP09) for the Derwent river catchment suggest drier summers (e.g. -15.1 to -19.4% change in summer precipitation in 2050; -18.5 to -23.1% in 2080), wetter winters and increased annual temperatures (e.g. +2.4 to +2.5 °C in 2050; +3.4 to +3.5 °C in 2080) under a medium greenhouse gas emission scenario. These could exacerbate flooding and slope instability and extend the areas susceptible to geohazards, posing further challenges for heritage management.