Cliff collapse monitoring with InSAR

Transcription

1 Gosia Mider PhD Researcher Supervisors: Dr. James Lawrence, Dr. Richard Ghail 12 th December 2018

2 AGENDA Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

3 Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

4 MOTIVATION About 10% of the world s population live in coastal zones Human activity and rising global sea level intensify the influence of erosion and flooding in the coastal areas Erosion effects are even worse in the UK due to high population density It s estimated that ~28% of England and Wales are eroding more than 100 mm/yr Coastal cliff instability is one of the most intense forms of the coastal erosion and it s very difficult to predict

5 EXAMPLE OF COASTAL INFRASTRUCTURE N Image from Google Earth

6 EXAMPLE OF COASTAL INFRASTRUCTURE N Image from Google Earth

7 BIRLING GAP COTTAGES - 70m of erosion in 100 years

8 BIRLING GAP COTTAGES - 70m of erosion in 100 years

9 CURRENT METHODS FOR MONITORING COASTAL ZONES Remote sensing techniques: Laser scanning methods Aerial photographs Instrumentation Field work and lab testing Taylor Patrick Survey Planning Design Merrett Survey Limited

10 PROPOSED SOLUTION - Data from ESA satellites, Sentinel-1A and Sentinel-1B is freely available Data acquired every 12 days (repeat frequency every 6 days) Surface deformation accuracy at the millimetre scale ESA

11 Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

12 LOCATION OF THE RECENT COLLAPSES June 2017 May 2016

13 COLLAPSE /05/2016 Brass Point (4 th sister) Cliff loss of 5-10m Collapse volume: ~ m 3 Simple vertical collapse from joint sets in Seaford Chalk Photos from Suzzy Berg (Mills) MSc

14 COLLAPSE /06/2017 During the hottest period of the summer Three consecutive collapses, first on 21 st, second and third 22 nd June Cliff loss of up to ~10m Total collapse volume ~ m 3 Rainfall above average in May 2017 Photos from Suzzy Berg (Mills) MSc

15 Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

16 METHODOLOGY PS: ENVI, SARScape software Time series created with images Coherence maps: ENVI software (Coherence CCD workflow) Comparison of before and after pairs of images

17 Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

18 PS 24/05/2016: 21/06/2017: 21 images 01/01/ /09/2016 Master: 18/04/ images 14/03/ /08/2017 Master: 06/06/2017

19 24/05/ /05/2016

20 21/06/ /06/2017

21 COHERENCE MAPS 24/05/2016: Two pairs: 30/04 (M) 12/05 (S) 30/04 (M) 24/05 (S) 21/06/2017: Two pairs: 12/06 (M) 18/06 (S) 12/06 (M) 24/06 (S)

22 COLLAPSE 2016 Before 30/04/2016 (M) 12/05/2016 (S)

23 COLLAPSE 2016 After 30/04/2016 (M) 24/05/2016 (S) Available images only 12 days apart (no Sentinel-1B at that time)

24 COLLAPSE 2016 Before 30/04/2016 (M) 12/05/2016 (S)

25 COLLAPSE 2016 After 30/04/2016 (M) 24/05/2016 (S) Available images only 12 days apart (no Sentinel-1B at that time)

26 COLLAPSE 2016 Single image 30/04 High tide

27 COLLAPSE 2016 Single image 24/05 Low tide

28 COLLAPSE 2017 before 12/06/2017 (M) 18/06/2017 (S)

29 COLLAPSE 2017 after 12/06/2017 (M) 24/06/2017 (S)

30 Introduction and motivation Recent collapses in chalk Methodology Results Summary and conclusions

31 SUMMARY So far results show a lot of potential for monitoring cliff collapses PS shows better results than coherence maps Coherence maps with different polarizations to be explored We need more collapses!

32 Thank you for listening!