Landslides in the East Midlands

Great Britain is not a country renowned for its large landslides. It lacks the extreme climatic events and the mountainous regions that are associated with catastrophic landslides events elsewhere in the world. Nevertheless, landslides in Britain do have significant societal and economic impacts. Meteorological Office statistics have shown that 2012 was the second wettest year since collation of national records began in 1910. Tragically, this also saw the highest number for many years of fatalities due to landslides, including those at Burton Bradstock in Dorset and at Looe in Cornwall. Even so, these landslides contrast with recent events in China, in Afghanistan and in Washington, USA, where large and calamitous events claimed many lives. However, landslides are common enough in Great Britain, and there is currently a heightened awareness of these geological hazards, and this was largely due to extensive media reports in 2012 and 2013

Nationwide monitoring of geohazards in Great Britain with InSAR: feasibility mapping based on ERS-1/2 and ENVISAT imagery

We model terrain visibility and topographic distortions to the ERS-1/2 SAR and ENVISAT ASAR IS2 satellite acquisition modes in Great Britain using the 5m NEXTMap DTM. Predictions of Persistent Scatterers (PS) densities identifiable over the landmass are drawn using the CORINE Land Cover 2006 dataset which is calibrated based on 6 PS datasets available for various areas of the UK. InSAR feasibility to monitor ground motions is discussed through the example of the Manchester area, with particular regard to landslide deposits in the Peak District

Simulating SAR geometric distortions and predicting Persistent Scatterer densities for ERS-1/2 and ENVISAT C-band SAR and InSAR applications: nationwide feasibility assessment to monitor the landmass of Great Britain with SAR imagery

We assess the feasibility of monitoring the landmass of Great Britain with satellite Synthetic Aperture Radar (SAR) imagery, by analysing ERS-1/2 SAR and ENVISAT IS2 Advanced SAR (ASAR) archive data availability, geometric distortions and land cover control on the success of (non-)interferometric analyses. Our assessment both addresses the scientific and operational question of whether a nationwide SAR-based monitoring of ground motion would succeed in Great Britain, and helps to understand controlling factors and possible solutions to overcome the limitations of undertaking SAR-based imaging of the landmass. This is the first time such a nationwide assessment is performed in preparation for acquisition and processing of SAR data in the United Kingdom, and any other country in the world. Analysis of the ERS-1/2 and ENVISAT archives reveals potential for multi-interferogram SAR Interferometry (InSAR) for the entirety of Britain using ERS-1/2 in descending mode, with 100% standard image frames showing at least 20 archive scenes available. ERS-1/2 ascending and both ENVISAT modes show potential for non-interferometric and single-pair InSAR for the vast majority of Britain, and multi-interferogram only for 13% to 38% of the available standard frames. Based on NEXTMap® Britain Digital Terrain Model (DTM) we simulate SAR layover, foreshortening and shadow to the ERS-1/2 and ENVISAT Lines-Of-Sight (LOS), and quantify changes of SAR distortions with variations in mode, LOS incidence angles and ground track angles, local terrain orientation, and the effect of scale due to the input DTM resolution. The simulation is extended to the ~ 230,000 km2 landmass, and shows limited control of local topography on the radar terrain visibility. According to the 50 m to 5 m DTM-based simulations, ~ 1.0–1.4% of Great Britain could potentially be affected by shadow and layover in each mode. Only ~ 0.02–0.04% overlapping between ascending and descending mode distortions is found, this indicating the negligible proportion of the landmass that cannot be monitored using either imaging mode. We calibrate the CORINE Land Cover 2006 (CLC2006) using Persistent Scatterer (PS) datasets available for London, Stoke-On-Trent, Newcastle and Bristol, to quantify land cover control on the PS distribution and characterise the CLC2006 classes in terms of the potential PS density they could provide. Despite predominance of rural land cover types, we predict potential for over 12.8 M monitoring targets for each acquisition mode using a set of image frames covering the entire landmass. We validate our assessment by processing with the Interferometric Point Target Analysis (IPTA) 55 ERS-1/2 SAR scenes depicting South Wales between 1992 and 1999. Although absolute differences between predicted and observed target density are revealed, relative densities and rankings among the various CLC2006 classes are found constant across the calibration and validation datasets. Rescaled predictions for Britain show potential for a total of 2.5 M monitoring targets across the landmass. We examine the use of the topographic and land cover feasibility maps for landslide studies in relation to the British Geological Survey's National Landslide Database and DiGMapGB mass movement layer. Building upon recent literature, we finally discuss future perspectives relating to the replication of our feasibility assessment to account for higher resolution SAR imagery, new Earth explorers (e.g., Sentinel-1) and improved processing techniques, showing potential to generate invaluable sources of information on land motions and geohazards in Great Britai

The National Landslide Database of Great Britain: acquisition, communication and the role of social media

The British Geological Survey (BGS) is the national geological agency for Great Britain that provides geoscientific information to government, other institutions and the public. The National Landslide Database has been developed by the BGS and is the focus for national geohazard research for landslides in Great Britain. The history and structure of the geospatial database and associated Geographical Information System (GIS) are explained, along with the future developments of the database and its applications. The database is the most extensive source of information on landslides in Great Britain with over 17,000 records of landslide events to date, each documented as fully as possible for inland, coastal and artificial slopes. Data are gathered through a range of procedures, including: incorporation of other databases; automated trawling of current and historical scientific literature and media reports; new field- and desk-based mapping technologies with digital data capture, and using citizen science through social media and other online resources. This information is invaluable for directing the investigation, prevention and mitigation of areas of unstable ground in accordance with Government planning policy guidelines. The national landslide susceptibility map (GeoSure) and a national landslide domains map currently under development, as well as regional mapping campaigns, rely heavily on the information contained within the landslide database. Assessing susceptibility to landsliding requires knowledge of the distribution of failures, an understanding of causative factors, their spatial distribution and likely impacts, whilst understanding the frequency and types of landsliding present is integral to modelling how rainfall will influence the stability of a region. Communication of landslide data through the Natural Hazard Partnership (NHP) and Hazard Impact Model contributes to national hazard mitigation and disaster risk reduction with respect to weather and climate. Daily reports of landslide potential are published by BGS through the NHP partnership and data collected for the National Landslide Database are used widely for the creation of these assessments. The National Landslide Database is freely available via an online GIS and is used by a variety of stakeholders for research purposes

Risk information services for Disaster Risk Management (DRM) in the Caribbean : operational documentation

The primary objective of this ESA project is to raise awareness within the World Bank (WB) of the capabilities of Earth Observation (EO) data and specialist service providers to supply information customised to the specific needs of individual projects. This project was set up within the ESA/WB eoworld initiative to contribute to the WB Caribbean Risk Information Program that is operating under a grant from the ACP-EU Natural Risk Reduction Program. The Caribbean is heavily affected by natural (and geo-) hazards with over 5 billion US$in losses in the last 20 years (source: CRED database). Figure 1 illustrates the division of natural disaster by occurrence in the region over the last 30 years, providing an insight into the impact in the region over a significant time period. A specific example of the environmental, social, economic and political issues that the project is addressing is highlighted by the effects of Hurricane Tomas on St Lucia in October 2010. The hurricane resulted in seven deaths with 5952 people severely affected, while the cost of the damage was estimated at US$336.2 million, representing 43.4% of GDP (ECLAC, 2011). Understanding and mitigating these “geo-environmental disasters” (as they are termed in ECLAC, 2011) is a primary concern in the region

Antecedent precipitation as a potential proxy for landslide incidence in South West UK

This paper considers the effects of antecedent precipitation on landslide incidence in the UK. During 2012-2013 an extraordinary amount of precipitation resulted in an increase in the number of landslides reported in the UK, highlighting the importance of hydrogeological triggering. Slope failures (landslides on engineered slopes) in particular caused widespread disruption to transport services and damage to property. SW England and S Wales were most affected. Easy-to-use and accessible indicators of potential landslide activity are required for planning, preparedness and response and therefore analyses have been carried out to determine whether antecedent effective precipitation can be used as a proxy for landslide incidence. It is shown that for all landslides long-term antecedent precipitation provides an important preparatory factor and that relatively small landslides, such as slope failures, occur within a short period of time following subsequent heavy precipitation. Deep-seated, rotational landslides have a longer response time as their pathway to instability follows a much more complex hydrogeological response. Statistical analyses of the BGS landslide database and of weather records has enabled determination of the probability of at least one landslide occurring based on antecedent precipitation signals for SW England and S Wales. This ongoing research is of part of a suite of analyses to provide tools to identify the likelihood of regional landslides occurrence in the UK

Creation of a national landslide domain map to aid susceptibility mapping in Great Britain

The need to develop a national map that characterises landslides across Gr eat Britain has long been recognised by the British Geological Survey as part of its strategic role providing hazard information to stakeholders. Hierarchical landslide domains represent areas of similar physiographic , meteorological, climatic and geologi cal characteristics that shaped the style of landsliding. Developed to underpin current research into how different types of landslides and terrains will be affected by changing environmental conditions , the map further assists development of a national l andslide susceptibility map with conditioning factors tailored to a specific domain. This paper considers the role of national - scale land systems mapping to create a Landslide Domain Map , the refinement of a national model using landslide inventories to b etter reflect the spatial extent and characteristics of landslides within domain s . The distribution of landsliding in Great Britain is a product of the complex range of lithologies and geomorphological processes active under a range of climatic conditions. The domain s represent landslides across a series of unstable slopes ranging from very large, ancient landslides formed under periglacial climate conditions to small, modern failures , particularly along transport infrastructure corridors . Although analysis of the National Landslide Database broadly informed the nature of landsliding within a specific domain, expert knowledge was needed to supplement it especially in areas where recent mapping had not taken place. Targeted data collection is planned in data - poor domains to supplement the database . Further domain - specific research is ongoing and includes development of semi - empirical process - specific models involving the weighting of critical factors in order to refine the current national landslide susceptibi lity map, GeoSure. As a n example of this refinement , this paper discusses an improved debris flow model for the Scottish Highlands

A combined geomorphological and geophysical approach to characterising relict landslide hazard on the Jurassic Escarpments of Great Britain

The Jurassic Escarpment in the North York Moors in Northern Britain has a high density of deep-seated relict landslides but their regional hazard is poorly understood due to a lack of detailed case studies. Investigation of a typical relict landslide at Great Fryup Dale suggests that the crop of the Whitby Mudstone Formation is highly susceptible to landslide hazards. The mudstone lithologies along the Escarpment form large multiple rotational failures which break down at an accelerated rate during wetter climates and degrade into extensive frontal mudflows. Geomorphological mapping, high resolution LiDAR imagery, boreholes, and geophysical ERT surveys are deployed in a combined approach to delimit internal architecture of the landslide. Cross-sections developed from these data indicate that the main movement displaced a bedrock volume of c. 1 × 107 m3 with a maximum depth of rupture of c. 50 m. The mode of failure is strongly controlled by lithology, bedding, joint pattern, and rate of lateral unloading. Dating of buried peats using the AMS method suggests that the 10 m thick frontal mudflow complex was last active in the Late Holocene, after c. 2270 ± 30 calendar years BP. Geomorphic mapping and dating work indicates that the landslide is dormant, but slope stability modelling suggests that the slope is less stable than previously assumed; implying that this and other similar landslides in Britain may become more susceptible to reactivation or extension during future wetter climatic phases. This study shows the value of a multi-technique approach for landslide hazard assessment and to enhance national landslide inventories