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
Study Area
Villa de Independencia, Bolivia
There were observed cracks in the downtown walls and wall collapse at the eastern bus station.
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 >
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
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
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
(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.
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
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
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
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