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Peat Landslides in Co. WicklowNoel Boylan and Michael LongThe aim of this project is to investigate geotechnical behaviour of peat susceptible to landsliding. Remotesensing techniques such as satellite imagery, aerial photography and Digital Elevation Models (DEM) wereused to detect slides in a study area of Co. Wicklow. Recently developed techniques (O’Liongsigh, 2004) wereused to assist the detection and further techniques were developed. This study has shown that the occurrenceof peat slides is not as significant in Wicklow as in the West of Ireland. This is possibly due to the fact that peatdeposits are generally thinner, and deep deposits are not very common in Co. Wicklow.The complex interaction between hydrology, underlying geology, geomorphology and geotechnical propertieshas been studied to try and understand the mechanisms of failure and areas of susceptibility. Further work isunderway to understand the geotechnical behaviour of the peat in landsliding and properties which may causecertain locations to be susceptible.Fig. 8.5 Peat Slide in Co. Wicklow. Osi 2000 Colour aerial photographs draped overDEM and viewed obliquely using 3D visualisation software at GSI. © Government ofIreland 2004 Osi Permit No. DNE 0001001.GIS Mapping of landslides & production of susceptibility mapsChristine Colgan (in association with GSI)The landslides that occurred in the west of Ireland in 2003 emphasised the need for a landslides database andsusceptibility mapping of the country.For the creation of this database in Microsoft Access, an inventory of previous landslides had to be compiled.Information was collected from research articles/journals and field observations (in the case of the Pollatomishlandslides). A webpage was also created to enlist landslides observed by the general public around the country(http://www.gsi.ie/workgsi/geohazards/myform.htm), the results from which were verified before being enteredinto the database.To date, the database contains 117 separate landslides, with information gathered about these events underthe headings:1. Location details2. Type of slide3. Size and extent4. Damage5. Causes6. Contributory factorsFrom this database a regional map that contains all known landslides in Ireland has been created usingGeographic Information Systems (GIS) with the type of landslide subdivided into the following five categories:bog flow, bog slide, creep, flow and rock fall. This database also provides a general source of information onlandslides in Ireland for interested parties.84
In the case of vulnerability mapping, geology (source: GSI), soil type (source: Teagasc) slope (source: OSI)and average rainfall (Met Eireann) maps were combined. It is hoped to ascribe values to each factor based onsusceptibility allowing for the creation of a slope stability/vulnerability map to be created. This map can then betested against known locations of landslides, for example the Pollatomish landslides.Fig. 8.6 Locations of known landslides in Ireland which have been subdivided by type of slide.Submarine slope failure morphology offshore IrelandGavin ElliotThe Irish offshore region is nearly 10 times the area of the Irish mainland. However up until the last 30 yearsvery little systematic work had been undertaken there, particularly the Atlantic margin (Fig. 8.5). Over the last20 years researchers at the Department of Geology at UCD together with DIAS and other institutes, have beeninvolved in attempting to unravel the mysteries of the Atlantic margin from deep crustal studies to seabedsurface morphology.The seabed morphology was poorly constrained until two extensive sidescan sonar surveys were undertakenin 1996 and 1998 respectively. These surveys imaged the numerous submarine canyons that incise the margin100 km west of Ireland. Integration of the sidescan sonar data with the existing seismic reflection data andbathymetry data revealed that the canyons could be up to 400m deep, in excess of 40 km long and in one caseenclosed in between 30° walls. The sidescan sonar also imaged (with resolution down to 5m) numerousheadwall scarps of submarine landslides. Only headwall scarps can be imaged as the main body of the failurehas been transported as debris flows into the deep basin and can be found on the basin floor.85
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Landslides in IrelandGeological Sur
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LANDSLIDESinIRELANDEditorRonnie Cre
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CONTENTSPreface ...................
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Fig. 4.3 Forces caused by water in
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PREFACEUntil recently Ireland has b
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een very important in populating th
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involves a report on the current st
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Main Objectives• Increase public/
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1. INTRODUCTIONRonnie Creighton1.1
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1.3 The Landslides PublicationThis
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Peat flows are not nearly so well d
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In Ireland the Quaternary or uncons
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Journal - published papersLetter -
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Fig. 3.1 Two images showing the use
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Table 3.1 Landslide Events Per Coun
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Fig. 3.3 Location map of the Pollat
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3.7.4 Quaternary GeologyQuaternary
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3.8 The Derrybrien Landslide - 2003
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• The classification scheme shoul
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The force causing the block to slid
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Plate 4.1 Herringbone drainage syst
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1210Number of events864Raised bogBl
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It is well known by research at Uni
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5. LANDSLIDE SUSCEPTIBILITY MAPPING
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Page 54 and 55: Platform / sensor pixel resolution(
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Page 62 and 63: elationships between developed susc
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Page 66 and 67: 50Fig. 5.12. Landslide susceptibili
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Page 79 and 80: CHAPTER 5.2 - TABLE APPENDIXBedrock
Page 81 and 82: 6. LANDSLIDES AND PLANNINGAileen Do
Page 83 and 84: 6.2.4 Development ManagementThe phy
Page 85 and 86: 6.5 Current Practice on Landslides
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Page 90 and 91: 2. MudflowsPlate 7.1 Rotational Lan
Page 92 and 93: 7.2 Carboniferous Cliff Lines (Co F
Page 95 and 96: 8. RESEARCH ON IRISH LANDSLIDESKoen
Page 97 and 98: 8.4 Research. Post-2003 AbstractsTa
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Page 103 and 104: Steep slopes in glacial tillMichael
Page 105 and 106: 9. RECOMMENDATIONS FOR FUTURE WORK9
Page 107 and 108: Priority 1 Peat slides and peat str
Page 109 and 110: TEXT REFERENCESAcreman, M., 1991. T
Page 111 and 112: Skipper, J., Follett, B., Menkiti,
Page 113 and 114: APPENDIX 2Glossary of TermsBlanket
Page 115 and 116: APPENDIX 3Nomenclature for Landslid
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Page 123 and 124: Hammond, R. 1979. The Peatlands of
Page 125: APPENDIX 7Useful Web Linkswww.gsi.i
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