Assessment of sediment delivery from shallow landslides in upland terrain using 3D remote sensing.

Galiatsatos, N.; Donoghue, D.N.M.; Dong, L.; Warburton, J.

Abstract

The well-publicised floods in North Yorkshire on 19 June 2005 focussed attention on the devastating impact of flash floods in the UK uplands. The North Yorkshire floods were considered so severe that they prompted an emergency debate in Parliament (29.06.05). The most severely affected area was the upper River Rye (catchment area 150 km2) in the North York Moors National Park where there was widespread valley floor flooding and multiple landslides, which added to the flood devastation. A preliminary survey of the area identified over 100 landslide scars including small shallow translational slides and two large peat mass movements, the largest of which extended over 3.5 hectares of heather moorland. The general objectives of this work are to i) assess the impact of the flood in terms of the sediment contribution from peat mass movements and shallow mineral landslides; and their link with channel erosion and sedimentation at the catchment scale; ii) quantify the amount of sediment removed by detailed morphological survey of a sample of landslide scars using surface models derived from aerial photography, modelling of airborne laser scanning data and ground survey techniques. Here we present a methodology for assessing sediment delivery from shallow landslides in upland terrain using 3D remote sensing. Landslide features were mapped photogrammetrically from 1:6,000 and 1:15,000 scale air photography with site conditions interpreted from the photography and Daedalus 1268 ATM multispectral data (visible, near infrared and thermal imagery). The remote sensing data were acquired by NERC (Natural Environment Research Council) Airborne Remote Sensing Facility as part of urgency procedures. Ground control was derived from DGPS, OS profile and NextMAP interferometric SAR data. Field survey of key landslide sites and geomorphic features provided quantitative data to model landslide volumes and patterns of erosion. Furthermore, historical aerial photography of the two large peat landslides will be used for comparison of pre- and after-event surface situation. The methodology uses large scale aerial photography from July 2001 and integrates them with aerial photography from August 2005 and airborne laser scanning (Optech ALTM3033 LiDAR) data from May 2006. High quality DEMs derived from airborne remote sensing allow detailed changes of the surface features to be quantified. Detailed elevation models of the landslide sites are required so that simple sediment budget models can be developed which are used to calculate the volume of sediment mobilised in the event and estimate how much material is lost from the site. This information is valuable in assessing the contribution of landslide sediment to the total sediment load of the flood event and determining the landscape settings where sediment delivery to the main river is maximised. Where the pre-landslide surface can be reconstructed in detail, differencing of pre and post landslide elevation models can generate surface displacement maps which can be used to test hypotheses of landslide failure mechanisms.

• Presentation Conference Type: Conference Paper (Published)
• Conference Name: 2007 Annual Conference of the Remote Sensing and Photogrammetry Society.
• Publication Date: 2008-11
• Publisher: Curran Associates
• Pages: 331-335
• Book Title: Remote Sensing and Photogrammetry Society Annual Conference (RSPSoc 2007): Challenges for Earth Observation: Scientific, Technical and Commercial. Proceedings of a meeting held 11-14 September 2007, Newcastle Upon Tyne, UK.
• Public URL: https://durham-repository.worktribe.com/output/1161400
• Publisher URL: http://www.proceedings.com/03288.html