An holistic approach to mapping the Quaternary geology and reconstructing the last glaciation of West County Mayo, Ireland, using satellite remote sensing and 'conventional' mapping techniques

PhDThe Quaternary geology of West County Mayo, Ireland, has appeared in the literature over 30 times since Close's account in 1867. Various glacial reconstructions have been proposed due to i) the complex sedimentology and morphology of the area, ii) different approaches having been adopted by researchers iii) models being tainted by theory-laden evidence as different glaciological concepts were in vogue at the time of publication. Corroboration of existing information was undertaken in this research along with de novo mapping and identification of new data. An holistic approach was adopted, with 'conventional' mapping techniques integrated with digital image processing of satellite imagery. Over 20OOkm2 were field-mapped where landforms such as drumlins, moraines, roche moutonnées, kames/kettle holes and eskers were recorded along with sedimentological data including till fabric analysis, deformation structure geometry, petrographic components, lithofacies etc. Radar (ERS-1) and optical multitemporal and multispectral Landsat-5 Thematic Mapper imagery were processed, evaluated and interpreted. Due to the absorption of H20 molecules in soil and plants between 1.55-1.751im, winter Landsat TM band 5 provided most information and was used for interpretation. Geological information from conventional mapping and digital remote sensing were integrated using an inversion model. The landscape was spatially divided into assemblages of landforms and relative chronologies were determined by analysing cross-cutting landforms. The data show that there was one ice mass with two 'domes' in the research area. The dome in Clew Bay had a north-south divide with ice flow towards the east in the eastern half of the bay and towards the west in the western half. The eastern margins of this dome diverted the Midlands ice to flow in a northerly direction. An older pattern of flow, towards the northwest, was recorded in the east of the area. The deposits indicate that a staged retreat occurred generally from north to south

Developing digital fieldwork technologies at the British Geological Survey

Geological Surveys are faced with budget constraints and calls for efficiency gains; the effective application of digital techniques is often seen as a route to meeting these demands while increasing the value of outcrop studies and reducing the inherent subsurface uncertainty. The British Geological Survey may be the oldest national Survey in the world (established in 1835); however, developing and implementing new, innovative and efficient technologies for fieldwork is a high priority. Efficient tools for capturing, integrating, manipulating and disseminating outcrop data and information are imperative to enable geoscientists to increase their understanding of geological processes and therefore to reduce subsurface uncertainty and risk. Systems for capturing structured digital field data and for visualizing and interacting with large datasets are increasingly being utilized by geoscientists in the UK and internationally. Augmented reality and unmanned aerial vehicles are amongst the developing technologies being explored for future operational implementation. This paper describes the digital field mapping (BGS·SIGMAmobile) and visualization (GeoVisionary) systems and refers to a case study outlining their contribution to reducing uncertainty and risk in hydrocarbon exploration

Risk information services for Disaster Risk Management (DRM) in the Caribbean : service readiness document

This document specifies the EO information products / services to be delivered in support of the World Bank project (Handbook for the Assessment of Landslide and Flood Hazards and Risks to Support Development Processes, led by ITC Netherlands), and describes the scope and extent of assessment that will be carried out following production and delivery. It is to be reviewed and agreed by the WB TTL for the project (and local users, if applicable), and will form the basis of subsequent activities to be carried out in the service assessment phase

Risk information services for Disaster Risk Management (DRM) in the Caribbean : mainstreaming opportunities

This document describes the assessment of opportunities for mainstreaming the satellite Earth Observation (EO) information products / services delivered by the British Geological Survey (BGS) via the framework of the European Space Agency (ESA) eoworld2 initiative. The products /services were delivered to the Caribbean region and the World Bank (WB) primarily via the ‘Caribbean Handbook on Risk Information Management’ project (CHARIM) which is financed by the EU-funded ACP-EU Natural Disaster Risk Reduction Program, managed by the Global Facility for Disaster Reduction and Recovery, led by the WB team, and implemented with the University of Twente, ITC and the local users from various Government Ministries in the Caribbean region. The prospect of increased exploitation and additional opportunities in further WB operations, programmes and initiatives is briefly addressed, as is an evaluation of further actions to be taken to further grow uptake of EO products / services across the WB in future

Risk information services for Disaster Risk Management (DRM) in the Caribbean : service utility document

This document describes the assessment of the Earth Observation (EO) information products / services delivered by the British Geological Survey (BGS) via the framework of the European Space Agency (ESA) eoworld2 initiative. The products / services were delivered to the Caribbean region and the World Bank (WB) primarily via the ‘Caribbean Handbook on Risk Information Management’ project (CHARIM) which is financed by the EU-funded ACP-EU Natural Disaster Risk Reduction Program, managed by the Global Facility for Disaster Reduction and Recovery, led by the WB team, and implemented with the University of Twente, ITC and the local users from various Government Ministries in the Caribbean region

Lithostratigraphy, sedimentation and evolution of the Volta Basin in Ghana

We present a revised lithostratigraphy for the Voltaian Supergroup of Ghana, based on a review of existing literature, interpretations of remotely sensed data and reconnaissance field survey of the Volta Basin. These strata thicken eastwards, to a maximum of between 5 and 6 km adjacent to the Pan-African Dahomeyide orogen. They began to accumulate some time after about 1000 Ma, along the margin of an epicontinental sea. Initial sedimentation, comprising the age-equivalent Kwahu and Bombouaka Groups, shows a cyclical mode of deposition controlled by eustatic changes in sea-level that produced a range of nearshore marine, littoral and terrestrial environments. A major erosional interval was followed by deposition of the 3–4 km thick Oti-Pendjari Group. Basal tillites and associated sandy diamictons are correlated with the Marinoan (end-Cryogenian) glaciation, indicating a maximum depositional age of about 635 Ma. The overlying cap carbonates and tuffs were deposited within a shallow epeiric sea bordered by a volcanically active rift system. The main part of the group records the transition from a rifted passive margin to a fully developed foreland basin receiving marine flysch in the form of argillaceous strata interbedded with highly immature wacke-type sandstones and conglomerates. Maximum accommodation space was developed within a foredeep adjacent to the Dahomeyide belt. Towards the end of the orogenic phase, the foredeep succession became partially inverted and then was buried under coarse terrestrial, red-bed molasse of the Obosum Group

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

Intermittent Small Baseline Subset (ISBAS) monitoring of land covers unfavourable for conventional C-band InSAR: proof-of-concept for peatland environments in North Wales, UK

This paper provides a proof-of-concept for the use of the new Intermittent Small Baseline Subset (ISBAS) approach to study ground elevation changes in areas of peat and organic soils in north Wales, which are generally, unfavourable for conventional C-band interferometric applications. A stack of 53 ERS-1/2 C-band SAR scenes acquired between 1993 and 2000 in descending mode was processed with both the standard low-pass SBAS method and ISBAS. The latter revealed exceptional improvements in the coverage of ground motion solutions with respect to the standard approach. The number of identified coherent and intermittently coherent pixels increased by a factor of 26 with respect to the SBAS solution, and extended the coverage of results across unfavourable land covers, particularly for coniferous woodland, bog, acid grassland and heather. The greatest increase was achieved over coniferous woodland, which showed ISBAS/SBAS pixel density ratios above 300. Despite the intermittent nature of the ISBAS solutions, ISBAS provided velocity standard errors generally below 1-1.5 mm/yr, thus preserving good quality of the estimated ground motion rates

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

Intermittent SBAS (ISBAS) InSAR with COSMO-SkyMed X-band high resolution SAR data for landslide inventory mapping in Piana degli Albanesi (Italy)

In the context of recent advances in InSAR processing techniques to retrieve higher persistent scatterer and coherent target densities over unfavourable land cover classes, this study tests the Intermittent Small Baseline Subset (ISBAS) approach to update the landslide inventory around the town of Piana degli Albanesi (Italy), an area where only 2% of the land appears suitable to generate radar scatterers based on a pre-survey feasibility assessment. ISBAS processing of 38 ascending mode and 36 descending mode COSMO-SkyMed StripMap HIMAGE SAR scenes at 3m resolution allows identification of ~726,000 and ~893,000 coherent and intermittently coherent pixels for the ascending and descending data stacks respectively. Observed improvements in the number of ISBAS solutions for the ascending mode are greater than 40 times compared to the conventional SBAS approach, not only for urban and rocky terrains, but also rural and vegetated land covers. Line of sight ground motion rates range between -6.4 and +5.5 mm/yr in 2008-2011, although the majority of the processed area shows general stability, with average rates of -0.6 mm/yr in the ascending and -0.1 mm/yr in the descending mode results. Interpretation of the ISBAS deformation rates, integrated with targeted field surveys and aerial photo-interpretation, provides a new and more complete picture of landslide distribution, state of activity and intensity in the test area, and allows depiction of very slow and extremely slow landslide processes even in areas difficult to access, with unprecedented coverage of results. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only