Multi-temporal archaeological and environmental...
Transcript of Multi-temporal archaeological and environmental...
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Multi-temporal archaeological and environmental prospection in Nasca (Peru) with ERS-1/2,
ENVISAT and Sentinel-1A C-band SAR data
Francesca Cigna (1,2), Deodato Tapete (1,2), Rosa Lasaponara (2), Nicola Masini (3)
(1) (2) (3)
12-13 November 2015 | ESA-ESRIN, Frascati (Rome), Italy
Day 1 – Session: Historical Landscapes and Environmental Analysis
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Cahuachi
Atarco
Nazca
Rio Taruga
Nazca lines
Palpa
N Nazca civilization (200 BC – 600 AD)
Region of Interest
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• Ceremonial Centre of Cahuachi • Aqueducts networks and drainage galleries (puquios) and reservoirs (ojos)
• Lines and geoglyphs of Nasca and Pampas de Jumana
Archaeological heritage
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Climate conditions Te
mpe
ratu
re Precipitation
Nasca
Climate: desert (Rio Grande valley) Precip.: virtually no rainfall during the year (tot. 4 mm per year) Temp.: 20.6°C (Palpa) and 20.9 °C (Nasca) on average (Feb.-Mar. the warmest; July the coldest)
Palpa
Tem
pera
ture
Precipitation
Sour
ce: h
ttp:
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.clim
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Project id.11073 Archaeological and environmental studies in the Nasca region (Southern Peru) using multi-temporal C- and L-band SAR imagery
Objectives • Change detection (evolution of the Rio Nasca catchment basin) • Archaeological surveying (puquios, buried structures) • Ground and structural deformation analysis and looting monitoring • Environmental assessment
ITACA – Italian mission of heritage Conservation and Archaeogeophysics
LASAPONARA & MASINI (2011) LASA
PON
ARA
et a
l. (2
011)
ESA & DLR Nasca projects
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ERS-1/2 SAR ImageMode • 20 scenes, desc. (1992-2010) • 80 scenes, asc. (2001-2011)
ENVISAT ASAR ImageMode IS2 • 15 scenes, desc. (2003-2005) • 5 scenes, asc. (2005-2007)
ALOS PALSAR scenes • 3 FineBeam, Dual Pol. (2007-2008)
ASAR imagery • Wavelength (λ): 5.6cm • Frequency (f): 5.3GHz • Look angle (θ): 22.8° • Orbit incl. (α): 12.9° • Repeat cycle: 35 days • Satellite altitude: 790 km • Pixel spacing: 8m (slant range) • Ground resolution: ~25-30 m
ENVISAT asc Track 175 Frame 6893
N
α
ENVISAT desc Track 311 Frame 3905
N
α
Satellite radar data at MR
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SLCs
Calibrated SLCs
Radiometric calibration
Level 0 (raw) IM data
Range/Doppler sequence
MLIs
Resampled SLCs & MLIs
ASTER GDEM
Multi-looking
Co-registration
Derived products
Spatio-Temporal analysis of the data
GTC MLIs
GTC derived products
Geocoding
Geocoding
Refined lookup table
SLC MLI
Master
Slaves
ASTER GDEM V2
Resampled MLIs Derived products
GTC MLIs & Derived products (map geometry)
Satellite data processing
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σi0 = f (λ, pol., θ, roughness, shape, dielectric properties)
σ0 [2003-2005] Normalized stdv σ0 [2003-2005] Average backscattering coefficient Normalized temporal variability
)(1
1
00 tn
ntt
ttii ∑
=
=
= σσ
Groundwater fluctuations and cropland changes along river plains
Alterations of local morphology due to mass movements
Radar signatures
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Dune ridges
Nazca
Airport
Pozo cocha
Rio Nazca
RGB
ASTE
R [2
003]
N
IR-R
ed-G
reen
RG
B AS
TER
[200
3]
NIR
-Red
-Gre
en
σ0 [2
003-
2005
] σ0
[200
3-20
05]
River courses and urban areas have higher σ0 than agricultural fields, dry and smooth surfaces (airport runaway and water bodies, e.g. pozo cocha)
Signal penetration depths are higher over the sand dunes of the Cerro Blanco, and σ0 is lower than over the surrounding mountain regions
Dune ridges
Radar signatures
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Panamericana Sur
Geoglyphs Group 1
Geoglyphs Group 2
Reptile
Panamericana Sur
Geoglyphs Group 1
Geoglyphs Group 2
Reptile
RGB ASTER [2003] NIR-Red-Green
σ0 [2003-2005]
Radar signatures
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RI_2
RI_1
Agricultural fields have different backscattering properties but similar temporal variations, hence are likely to follow groundwater fluctuations over the different seasons
Temporal variations
)(1)(1
00 tN
tNi
iiAOI ∑
=
=
= σσt = acquisition time N = no. pixels within AOI i = ith pixel
• Comparison of temporal variability of radar returns from different surfaces • Temporal history of average σ0 within different AOIs
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)()(
0
0
0
ji
ki
tt
Ri σ
σσ
=
)()( 00kiji tt σσ >
)()( 00kiji tt σσ <
0 < R < 1 if
R > 1 if
15/11/2005
04/02/2003
Ratio
Rio Ingenio plain
3x3 or 5x5 spatial filtering
Change detection
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Increased radar backscattering
Decreased radar backscattering
Decreased radar backscattering
P4
P5
P1
P2 P3
ASTER 30/05/2003
ASTER 01/06/2004
P4
P5
P1
P2 P3
P1
P2 P3
P5
2004-2005: decreased σ0 along the Rio Ingenio plain, except P1-P3 (ratio over 4-5) May-Nov2005: decreased soil moisture over vegetated/agricultural areas
May2003 vs. Jun2004 (ASTER): decreased vegetation cover and soil moisture
Change detection
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Hydraulic networks
Ancient puquios in the Taruga valley
ASTER-derived NDVI
SAR colour composite
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15/04/2003 04/02/2003 24/06/2003
RGB
a
b
a
b
Wind/rain-driven morphological
changes and mass movements cause local alterations of the backscattering
coefficient
Mass movements
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20041130_20050524 Bperp: 5 m Btemp: 175 days
1
0
InSAR coherence cross-correlation between co-registered SLCs
Cahuachi
Changes along river plains and over agricultural fields
Wind/rain-driven mass movements
Landscape changes at regional scale
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20030204_20041130 Bperp 89 m Btemp 665 days
20041130_20050524 Bperp 5 m Btemp 175 days
20030204_20051115 Bperp 343 m Btemp 1015 days
DESC
mod
e AS
C m
ode
20051002_20071007 Bperp 4 m Btemp 375 days
20071007_20071111 Bperp 180 m Btemp 35 days
Rio Nazca
Cahuachi
Landscape changes at local scale
1
0
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From historical to recent landscape evolution
Oct. 2014
Baseline pre-defined mission observation scenario • IW mode • VV polarization • 24 days repeat cycle per pass
(asc./desc.) and alternating the passes asc./desc. (i.e. areas observed every 12 days.
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From historical to recent landscape evolution
S1 GRD IW VV 25th Oct. 2014
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From historical to recent landscape evolution
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From historical to recent landscape evolution
R: 25 Oct. 2014 G: 12 Dec. 2014 B: 18 Mar. 2015
R: 25 Oct. 2014 G: 12 Dec. 2014 B: 18 Mar. 2015
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ERS-1/2 and ENVISAT C-band satellite radar data imaged the recent evolution of cultural landscape in Nasca since 1997
SAR data proved capable to depict archaeological features, and to identify surface indicators of environmental changes in such a dynamic region
Amplitude-based and coherence change detection reveal soil moisture and vegetation changes occurring along the river valleys
Mass movements and other surface processes occur at seasonal and yearly scales across the Rio Grande catchment area
Natural and anthropogenic factors expose the heritage of Nasca at risk
Results with archive data show potential for environmental and archaeological studies with new Sentinel-1 imagery
Future research will look at analysing the relationship between landscape evolution and climate change over the last 20+ years
Conclusions & future research
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Thanks! REFERENCES • CIGNA F., TAPETE D., LASAPONARA R., MASINI N. 2013. Amplitude change detection with ENVISAT ASAR to
image the cultural landscape of the Nasca region, Peru. Archaeological Prospection, 20(2), 117-131.
• TAPETE D., CIGNA F., MASINI N., LASAPONARA R. 2013. Prospection and monitoring of the archaeological heritage of Nasca, Peru, with ENVISAT ASAR. Archaeological Prospection, 20(2), 133-147.
• TAPETE D., CIGNA F., LASAPONARA R., MASINI N. 2014. Investigating natural hazards in the Peruvian region of Nasca with spaceborne radar sensors. In: K. Sassa et al. (eds.), Landslide Science for a Safer Geo-Environment, 3, 357-362.
• TAPETE D., CIGNA F., LASAPONARA R., MASINI N. 2015. Multi-scale detection of changing cultural landscapes in Nasca (Peru) through ENVISAT ASAR and TerraSAR-X. In: G. Lollino et al (eds.) Engineering Geology for Society and Territory, 8, 339-343.
...coming soon
• TAPETE D. & CIGNA F. 2016. SAR for landscape archaeology. In: Masini N. & Soldovieri F. (eds). Sensing the Past: Geoscience and Sensing Technologies for cultural heritage. Springer. 15 pp.