The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Voi XXXVII. Part BI. Beijing 2008 
260 
5. RESULT 
The PSInSAR results measured an average of 5 millimetres 
deformations per year in study area while aerial 
photogrammetry results are observed approximately 2.8 
millimetres per year in same test area. Table 3 is mean and 
standard deviation of deformation from PSInSAR result at 
research area. 
p Deformation 
c Deformation 
PSInSAR 
-5 mm/yr 
2 mm/yr 
Table 3. Deformation result of PSInSAR 
By having the PSInSAR results overlaid with the optical image 
and groundwater extraction sites in ArcGIS, it is possible to 
recognize the location of the highset deformation rate 
corresponding to the period of times. Furthermore, it is possible 
to investigate the effect of groundwater extraction on the urban 
deformation. In addition, aerial photogrammetry result confirms 
the deformation rate from PSInSAR result and investigates the 
deformation of each object. 
Figure 9. Aerial photogrammetry result superimposed on the 
Google image 
p Deformation 
a Deformation 
Aerial photo 
-2.8 mm/yr 
2.7 mm/yr 
Table 4. Deformation result of Aerial photogrammetry 
6. CONCLUSION 
In order to observe the patterns of overall deformation rate, 
spatial filtering was applied to the Sydney result. We can show 
the overall patterns of subsidence rate towards underground 
structures such as aquifer in this way. In PSInSAR result, the 
highest deformation rate, up to -9 mm/yr, is observed in Eastern 
Suburb especially along the Botany Sands Aquifer which is the 
biggest aquifer in Sydney. The rain water comes in from the 
north, it soaks into the sandy aquifer which begins at Centennial 
park and flow to the Botany Bay. In the PSInSAR result, around 
Kensington has been observed with highest deformation. This 
might due to the reduction in groundwater level in area 
surrounding Centennial Park. The groundwater extraction along 
the groundwater flow path caused the groundwater in 
Centennial park flow to Botany Bay where the mineral in the 
sand is carried away by the groundwater. Aerial 
photogrammetry result shows the detail information due to the 
groundwater extraction at the biggest deformation region; 
around the Centennial Park. The highest deformation rate is 
approximately -lOmm/yr and some building is arise 0.2mm/yr. 
PSInSAR and aerial photogrammetry results have similar 
subsidence pattern in the test field. In this study, we can confirm 
that PSInSAR and aerial photogrammetry have different 
advantage in ground deformation analysis. Aerial 
photogrammetry results have detail information of each 
building and object. However, research coverage is small and it 
is difficult to find the overall pattern. PSInSAR results have 
large coverage and overall pattern in the test field. In summery, 
combination of two methods for ground monitoring is not only 
supporting the each technique weakness but also saving the 
processing time and improving the effectiveness of PSInSAR 
data. 
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