Local scale investigation and modelling of geohazards at the Derwent Valley Mills World Heritage Site

Novellino A.1, Harrison A.M.1, Hobbs P.R.N.1, Wang L.1, Bee E1 1 British Geological Survey Keyworth, Nottingham, NG12 5GG. United Kingdom

The Derwent Valley Mills World Heritage Site (DVMWHS) is the birthplace of the modern factory system. The Derwent Valley, and its associated mill complexes, infrastructure and housing facilities were included in the UNESCO World Heritage List in 2001. In the 18th and 19th century, it saw the successful combination of the essential ingredients for factory production, with Water Power applied at a large scale for the first time. This led to the development of new technology for spinning cotton, and the first modern industrial settlements. The DVMWHS is one of the PROTHEGO case study sites, allowing focussed research on local scale monitoring, investigation and advanced modelling.

PROTHEGO Project Work Package 6

Local scale investigation and advanced modeling

in selected Test Sites

-Workshop -

UNESCO World Heritage Sites of Europe affected by Geo Hazards Satellite monitoring future challenges - The PROTHEGO project contribute

UNESCO Headquarters – Paris , March 23th, 2018

http://www.prothego.eu/

The DVMWHS is mostly overlain by fluvial and mass movement deposits with glacially-derived till deposits. The underlying bedrock geology predominantly consists of interbedded mudstone, siltstone and sandstone. The alternating permeable and impermeable rocks can frequently give rise to landslide susceptibility, especially so if the river undercuts the toe of the steep-sided slopes. Analysis of the British Geological Survey GeoSure dataset demonstrates that, despite the majority of the DVMWHS area is attributed to very-low to low susceptibility hazards, landslide and flooding susceptibilities for the area are slightly higher.

In order to monitor the current state of activity of the identified geohazards, Sentinel-1 spaceborne imagery acquired between 2015 and 2017 have been processed using the Interferometric Synthetic Aperture Radar (InSAR) technique. The ground stability conditions reveal that, globally, the land is not moving apart from three areas: two of them correspond to active landslides in Starkholmes and Ambergate which might impact the World Heritage while, in Belper, the radar data identified damage connected to a recent flooding event.

UKCP09 medium emissions scenarios predict the area will experience drier, warmer summers, wetter winters with higher intensity rainfall events, with similar overall annual rainfall. This could significantly increase both the landslide and flooding susceptibility. Analysis shows that landslide events often coincide with an unusually low Soil Moisture Deficit, such as that which occurred in June 2012 within a wider and notably irregular summer pattern which is also reflected in a period of high summer rainfall. InSAR results confirm that the movement is still ongoing at a constant rate. Based on the analysis of linkage of hydrological components to historical events, an index method was developed to generate flood susceptibility maps for the future.

• This study reveals that the principal geohazards within the DVMWHS are landslides and fluvial and groundwater flooding. The other shallow geohazards assessed within the study area have a comparably lower susceptibility, and the consequences would potentially be smaller.

• Two landslide locations are identified that could impact the WHS in the future; Starkholmes and Ambergate. InSAR data confirms the landslide susceptibility data and the active state of the high susceptibility landslide hazard. In Belper, the radar data identified the damage connected to the recent flooding event.

• This work has highlighted the potential for future research to aid the protection of WHS’s from sources of hazard within the site, but, there has been no suggestion of implementing specific mitigation measures or on the cost-benefit analysis of possible mitigation alternatives. However, modified drainage patterns, dependant on localised conditions (wells and drains), drainage maintenance, floodwalls and floodgates, raising community awareness (flood risk maps) to allow individuals to take action appears to be the initial response to these shallow processes.

• Antecedent rainfall is a major driver of the occurrence of the principal geohazards, and therefore the frequency and magnitude of these geohazards will be affected by future climate change. With the release of UKCP18 projections imminent, this is also an opportunity to strengthen the resilience of UNESCO heritage sites to future climatic fluctuations.

alessn@bgs.ac.uk

R E F E R E N C E S CIGNA, F., HARRISON, A., TAPETE, D., LEE, K., 2016. Understanding geohazards in the UNESCO WHL site of the Derwent Valley Mills (UK) using geological and remote sensing data. In Fourth International Conference on Remote Sensing and Geoinformation of the Environment (pp. 96881V-96881V). International Society for Optics and Photonics. PENNINGTON, C. V. L., DIJKSTRA, T. A., LARK, M., DASHWOOD, C., HARRISON, A. M., FREEBOROUGH, K. A. AND REEVES, H. J. “Antecedent precipitation as a potential proxy for landslide incidence in the UK,” Proc. Third World Landslide Forum, Landslide Science for a Safer Geoenvironment 253-259 (2014).

A C K N O W L E D G M E N T S The authors would particularly like to thank the following stakeholders for their background knowledge and input regarding their needs and requirements when managing the Derwent Valley Mills WHS. • Adam Lathbury (Head of Derbyshire County Council’s Conservation, Heritage and Design Service) • Adrian Farmer (DVMWHS Heritage Co-ordinator) • David Knight (Head of Research, Trent & Peak Archaeology) • Andy Howard (Environmental Consultant) • Mark Suggitt (Retired DVMWHS Site Manager)

Image courtesy of The Derwent Valley Mills Partnership

Images courtesy of The Derwent Valley Mills Partnership

Image courtesy of The Derwent Valley Mills Partnership

Sir Richard Arkwright is known as “the father of the factory system”. The Arkwright System integrated the machinery and the workforce around a common source of motive power.

Permanent Delegation of Italy to UNESCO