ul 2004 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
a b 
  
Figure 6. Change detection using images difference 
a - color composite image May 27, 1986 ; b - color composite image April 27, 1993 c - difference image 
3.4 NDVI Image differrencing 
Difference images were created by first calculating NDVI 
values for each date of imagery by following equation: 
NDVI =( XS3— XS2)/( XS3+ XS2) (2) 
A difference was created by subtracting one date of NDVI 
values from those of the previous date: 
DIF [8693] = NDVI[93] - NDVI [86] (3) 
4. DISCUSSION AND CONCLUSIONS 
The principal changes distinguished with the image obtained by 
differencing the classifications of the two composite images 
have been: 
767 
the increased variation of shore lines characterised by 
(deposition) or forwards to sea or retreating zones 
(erosion zones). In study zone are revealed especially 
expansion zones with amplitudes of 1.5-5 pixels 
(beaches from east and south-east of Sulina town, 
agricultural polders Pardina and the one from south of 
Sulina town, mouth of Chilia branch, neighbouring of 
south-east zone of Rosu lake); 
changing of the lakes shape dues to floating reed islet 
formation moving (lakes: Fortuna, Gorgova, Lumina, 
Puiu); 
decreasing of compactly common reed areas where this 
was intensively exploited (for instance decreasing with 
25-30% of some areas of south lakes Rosu, north-east of 
Razim lake and between Sulina branch and Lumina 
lake) and extensions of areas with common reed- mace 
reed mixture; 
news channels opening (parallel to shore line the 
channel Tataru and the channels for agriculture Sulina 
precinct plotting of land), six shortcuts of Sf. Gheorghe 
branch and news fishery areas from east Caraorman 
locality, Popina, north Mahmudia and others.