Monitoring Land Subsidence in Ho Chi Minh City UsingMonitoring Land Subsidence in Ho Chi Minh City Using

Radar Radar InterferometryInterferometryRadar Radar InterferometryInterferometryHo Tong Minh

Dipartimento di Elettronica e Informazione

ABSTRACTABSTRACT

The level of the ground water has been constantly lowering and the urbanization has been rapidly developing during the last dThe level of the ground water has been constantly lowering and the urbanization has been rapidly developing during the last d

which has led to the subsidence of some areas in the Ho Chi Minh City (HCMC). Land deformation at the rate of few which has led to the subsidence of some areas in the Ho Chi Minh City (HCMC). Land deformation at the rate of few

water pumping stations.water pumping stations.

This poster demonstrates the effectiveness of radar This poster demonstrates the effectiveness of radar interferometryinterferometry to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land This poster demonstrates the effectiveness of radar This poster demonstrates the effectiveness of radar interferometryinterferometry to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land

subsidence phenomenon in HCMC using ERS SAR SLC scenes acquired over HCMC.subsidence phenomenon in HCMC using ERS SAR SLC scenes acquired over HCMC.

INTRODUCTION

Subsidence in Ho Chi Minh City is a long term problemSubsidence in Ho Chi Minh City is a long term problem

•• ConvensionalConvensional methods : precise methods : precise levellinglevelling and GPS and GPS –– they are costly and they are costly and

time consumingtime consuming

•• Radar Radar InterferometryInterferometry –– Permanent Permanent ScattererScatterer InSARInSAR -- economical, fast, economical, fast,

provides information on a large areaprovides information on a large area

1950-1975

2 M.

1975-2005

8 M.

1700-1950

0,5 M.

2 M.

2020 Year

12 M. Inhabitant.

Average backscatter intensity Urbanized direction and population

METHODS

The Interferometric Concept

RR

RR11

RR22

The The unitunit ofof lengthlength usedused in in InSARInSAR isis the the wavelengthwavelength::

RR11

RR22

∆∆RR

∆∆∆∆∆∆∆∆R = c R = c ·· ∆φ∆φ∆φ∆φ∆φ∆φ∆φ∆φInterferometryInterferometry

λλλλλλλλ = 5.66 cm= 5.66 cm

∆φ∆φ∆φ∆φ∆φ∆φ∆φ∆φ

∆∆RR∆∆∆∆∆∆∆∆ rr

λλλλλλλλ = 5.66 cm= 5.66 cm

RR11

RR22

DInSAR limiting factors:DInSAR limiting factors:

•• reflectvity changesreflectvity changes

The PS Technique

RR11

RR22

•• reflectvity changesreflectvity changes

•• atmospheric disturbancesatmospheric disturbances

RR22

∆∆RR

By using:By using:

•• long temporal series of SAR datalong temporal series of SAR data

identification of:identification of:

•• coherent radar targets:coherent radar targets:

the the Permanent Scatterers (PS)Permanent Scatterers (PS)

PSPSwhere atmospheric effects can bewhere atmospheric effects can be

estimated and removedestimated and removed

Observed interferometric phase is the sum of many termsObserved interferometric phase is the sum of many terms

φinsar = φdef + φtopo + φatm + φorbit + φnoise

PS pixelsPS pixelsPS pixelsPS pixels

have lowhave low

noisenoise

Monitoring Land Subsidence in Ho Chi Minh City UsingMonitoring Land Subsidence in Ho Chi Minh City Using

InterferometryInterferometry TechniquesTechniquesInterferometryInterferometry TechniquesTechniquesHo Tong Minh Dinh

Informazione, Politecnico di Milano

The level of the ground water has been constantly lowering and the urbanization has been rapidly developing during the last dThe level of the ground water has been constantly lowering and the urbanization has been rapidly developing during the last decaecades due to the strong groundwater extraction des due to the strong groundwater extraction

which has led to the subsidence of some areas in the Ho Chi Minh City (HCMC). Land deformation at the rate of few which has led to the subsidence of some areas in the Ho Chi Minh City (HCMC). Land deformation at the rate of few centimetrescentimetres per year can be measured at the heavy ground per year can be measured at the heavy ground

to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land to detect the deformations in HCMC. The goal is to employ this powerful new technique to measure the land

RESULTS

total temporal spatial doppler thermalρ ρ ρ ρ ρ=

Total correlation, Total correlation, ρtotalρtotal

Data ERS-1 & 2

ρ denotes correlation ρ denotes correlation

HO CHI MINH MAP

TAY NINH

107°0'E 106°45'E 106°30'E

Subsidence trend

TAY NINH

DONG NAI

SUBURBAN REGION

URBAN FRINGE REGION

11°0'N 11°0'N

BINH DUONG

LONG AN

BA RIA

SUBURBAN REGION

URBAN INNER CORE REGION 10°45'N 10°45'N

10°30'N 10°30'N

107°0'E 106°45'E 106°30'E

SUBURBAN REGION URBAN FRINGE REGION URBAN INNER CORE REGION STUDY AREA

Interpretation

WWe see that e see that the some Southwest subsidencethe some Southwest subsidence areas coincide. areas coincide. TThe most he most

reliable information is in the zone were the PS are concentratedreliable information is in the zone were the PS are concentrated. .

CONCLUSIONS

reliable information is in the zone were the PS are concentratedreliable information is in the zone were the PS are concentrated. .

Moreover, lMoreover, looking at the position of the “ooking at the position of the “subsidence subsidence zones”, zones”, most of most of

tide flood sites lie tide flood sites lie at theat these areas se areas of the city (as expectedof the city (as expected). ).

-- The capability of using PS techniques to map land subsidence The capability of using PS techniques to map land subsidence

phenomenon in Ho Chi Minh City. phenomenon in Ho Chi Minh City.

-- Progressing urbanization and a rising population cause more Progressing urbanization and a rising population cause more

CONCLUSIONS

-- Progressing urbanization and a rising population cause more Progressing urbanization and a rising population cause more

exploitation of undergroundexploitation of underground--waterwater and more large and more large structures to be structures to be

built. This is effecting HCMC surface causing significant ground built. This is effecting HCMC surface causing significant ground

deformation.deformation.

1.1. FerrettiFerretti, A., C. , A., C. PratiPrati, and F. , and F. RoccaRocca, (2000). Nonlinear subsidence rate estimation using permanent , (2000). Nonlinear subsidence rate estimation using permanent scatterersscatterers in differential SAR in differential SAR interferometryinterferometry, IEEE Trans. , IEEE Trans. GeosciGeosci. Remote Sens., 38(5), 2202. Remote Sens., 38(5), 2202––2212. 2212.

2.2. Hooper, A., P. Hooper, A., P. SegallSegall, and H. , and H. ZebkerZebker, (2007). Persistent , (2007). Persistent scattererscatterer interferometricinterferometric synthetic aperture radar synthetic aperture radar

BIBLIOGRAPHY

2.2. Hooper, A., P. Hooper, A., P. SegallSegall, and H. , and H. ZebkerZebker, (2007). Persistent , (2007). Persistent scattererscatterer interferometricinterferometric synthetic aperture radar synthetic aperture radar for crustal deformation analysis, with application to for crustal deformation analysis, with application to VolcánoVolcáno AlcedoAlcedo, Galápagos, Journal of Geophysical , Galápagos, Journal of Geophysical Research, Vol. 112, B07407, doi:10.1029/2006JB004763.Research, Vol. 112, B07407, doi:10.1029/2006JB004763.

3.3. Le Van Le Van TrungTrung and Ho Tong Minh and Ho Tong Minh DinhDinh. Monitoring Land Deformation Using Permanent . Monitoring Land Deformation Using Permanent ScattererScatterer INSAR INSAR Techniques Techniques –– Case Study: Ho Chi Minh City. 7th FIG Regional Conference, Hanoi, Vietnam, October 2009.Case Study: Ho Chi Minh City. 7th FIG Regional Conference, Hanoi, Vietnam, October 2009.