The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
177 
4%2% 
31% 
□ 0-2mm 
■ 2-4mm 
□ 4-6mm 
□ 6-8mm 
■ 8-10mm 
□ 10-12mm 
Figure 10. The percentage of errors by PS technique 
4 %2%% 
□ 0-2mm 
■ 2-4mm 
□ 4-6mm 
□ 6-8mm 
■ 8-10mm 
□ 10-12mm 
■ >12mm 
Figure 11. The percentage of errors by STUN technique 
6. DISCUSSION AND ANALYSIS 
From the subsidence results shown in the figure 4 and figure 6 
of two periods, we can find the distribution of main subsidence 
regions are basically uniform. In order to probe into the cause 
and change of subsidence in recent years in Shanghai urban, we 
divide the test area into 5 regions according to the districts of 
Shanghai. We can analyze the cause in the following two 
aspects: exploitation of underground water showed in figure. 13 
(we use pumpage of ground water in 2000 as the average 
pumpage since annual pumpage of ground water remains almost 
unchanged in the past decade) and urban land use showed in 
figure. 14 (including the use of residence land, industrial land, 
commercial land and municipal engineering constructions in 
2005). And we also can describe the change of the subsidence 
in test area according to the above processing results in two 
different periods. 
Figure 12. A-E regions in test area 
Region A B C D E G E 
Recharge 
r mWJ 
10* im 3 / v 
250 ' 
500 
Aquifer 
One Two Three Four 
i 
Figure 13. The pumpage of 
ground water of 5 regions of 
Shanghai in 2000 
Urtam land 
Iw Ralto 
Figure 14. The urban land use 
ratio of 5 regions of Shanghai 
in 2005 
Figure 15. Comparison of average subsidence velocities 
obtained by PS in 1993-2000 and that by STUN in 2003-2005