Twelve-Year Landslide Risk Assessment in Villa de Independencia, Bolivia… · 2020-05-06 · Villa...
Transcript of Twelve-Year Landslide Risk Assessment in Villa de Independencia, Bolivia… · 2020-05-06 · Villa...
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Twelve-Year Landslide Risk Assessment in Villa de Independencia, Bolivia, with Sentinel-1 and
ALOS-1/2 InSAR Observations
Chuang Song, Zhenhong Li, Stefano Utili, Chen YuNewcastle University
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Study Area
Villa de Independencia, Bolivia
There were observed cracks in the downtown walls and wall collapse at the eastern bus station.
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Data
2015 2016 2017 2018 2019Time (year)
-200
-100
0
100
Spat
ial B
asel
ine
(m)
2015 2016 2017 2018 2019Time (year)
-100
0
100
200
Spat
ial B
asel
ine
(m)
(b) Sentinel-1 descending
(c) Sentinel-1 ascending
2008 2010 2012 2014 2016 2018Time (year)
-2000
-1000
0
1000
2000Sp
atia
l Bas
elin
e (m
)(a) ALOS-1 and ALOS-2
ALOS-1 ascending
ALOS-2 ascending
ALOS-2 descending< ALOS-2 images are too few to apply timeseries InSAR, so interferometry only >
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Flowchart of Time Series InSAR
LOS velocityand
time series
Selectedinterferograms
SLCimages
ResampledSLC images
Coregistration Grouping pairsRemoval of DEM
GACOS troposphericdelay correction
Correctedinterferograms
First-roundcoherent pixels
Dispersionof amplitudePhase noiseSecond-round
coherent pixels estimation
Phase correction forspatially-uncorrelated noise
Wrappedphase images
Unwrappedphase images
3D phaseunwrapping
Correct spatially-correlated noise
StaMPS
/SBAS
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Results | Displacement velocity maps
-66.84 -66.82 -66.8 -66.78
-17.11
-17.1
-17.09
-17.08
-17.07
-17.06
-17.05
-50
-40
-30
-20
-10
0
10
20
30
40
50mm/yr
-66.84 -66.82 -66.8 -66.78
-17.11
-17.1
-17.09
-17.08
-17.07
-17.06
-17.05
-50
-40
-30
-20
-10
0
10
20
30
40
50mm/yr
(c) Sentinel-1 descending (2014 to 2019)
-66.84 -66.82 -66.8 -66.78
-17.11
-17.1
-17.09
-17.08
-17.07
-17.06
-17.05
-50
-40
-30
-20
-10
0
10
20
30
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50mm/yr
-66.84 -66.82 -66.8 -66.78
-17.11
-17.1
-17.09
-17.08
-17.07
-17.06
-17.05
-50
-40
-30
-20
-10
0
10
20
30
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50mm/yr
(d) Sentinel-1 ascending (2014 to 2019)
(a) ALOS-1 ascending (2007 to 2011) (b) ALOS-2 ascending (2015 to 2017)
Town Centre
Highway 25
Town Centre
Highway 25
Town Centre
Highway 25
Town Centre
Highway 25
Risky Area Risky Area
Risky AreaRisky Area
A landslide risky area below Highway 25, with the displacement velocity of about 30 mm/yr in the Line of Sight (LOS), is detected.
The town centre needs a further check usingSentinel-1 results in high temporal resolution.
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Results | InSAR time series in the Risky Area
2008 2010 2012 2014 2016 2018Time (year)
-200-100
0100
LOS
(mm
)
ALOS-1 AscendingSentinel-1 DescendingSentinel-1 AscendingALOS-2 Ascending
The temporal behaviour in descending and ascending LOS coincides well illustrating a
slowdown process from mid 2017.
The detected landslide risky area below Highway 25 is in a lower failure risk than before, but
the low risk may be temporary considering the same slowdown process from 2008 to 2010.
2008 2010 2012 2014 2016 2018Time (year)
-200
-100
0
100
LOS
(mm
)
2020
slowdown
the same slowdown process but accelerated after 2010
Mid 2017
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Results | Cumulative LOS displacements in the Downtown
The spatial distribution of Sentinel-1 LOS displacements in descending and ascending
modes suggests that the town centre and its upper block move with different east-west
sliding due to different slope aspect.
Town Centre
Upper Block
Sentinel-1 descending Sentinel-1 ascending
Town Centre
Upper Block
Town Centre
Upper Block
Slopeaspect
Slope aspect
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Results | InSAR time series in the Downtown
2008 2010 2012 2014 2016 2018Time (year)
-40
-20
0
20
40
LOS
(mm
)
0
50
100
150
200
250
30-d
ay a
cc. p
reci.
(mm
)
2008 2010 2012 2014 2016 2018Time (year)
-20
0
20
40
60
LOS
(mm
)
0
50
100
150
200
250
30-d
ay a
cc. p
reci.
(mm
)
Acceleration
Note: The daily precipitation data wascollected from NASA GPM and convertedto 30-day accumulated precipitation totals.LOS deformation in descending andascending modes have differentsensitivities to the slope geometry.
• The deformation time series from Sentinel-1 present acceleration in early 2018 and 2019, which is cross-validated by ALOS-2 measurements.
• The two accelerations have similar initiating time and durations, in response to increase precipitation in the late rainy season.
Note: The upper block holds too few coherent pixels byALOS-2, so no ALOS-2 results for it.
(a) Town Centre
(b) Upper Block AccelerationWe thought the acceleration is a signal of landslide activation in the downtown.
2008 2010 2012 2014 2016 2018Time (year)
-200204060
LOS
(mm
)
0100200
30-d
ay a
cc. p
reci.
(mm
)
ALOS-1 AscendingSentinel-1 DescendingSentinel-1 AscendingALOS-2 AscendingALOS-2 DescendingPrecipitation
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Ø Displacement velocity from Sentinel-1, ALOS-1 and ALOS-2 data spanning
twelve years revealed a landslide risky area below Highway 25.
Ø Combining InSAR measurements in descending and ascending modes helps
identify two sub-blocks of landslides in the town.
Ø The activation of landslides from 2018 in Villa de Independencia was found,
possibly being related to the increased precipitation in the late rainy season.
Thanks!Email: [email protected]
Conclusion