International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
Where Y is an area of delta occupied by investigated ecological
facies; X, is the conventional year of the process beginning for
facies area decrease; X; is the year of aerospace images. The
area dynamic trend is exemplified by the figure 8 for stagnant
water, compactly common reed, mixture common reed-mace
reed and forest vegetation habitats from the Sulina site.
4. CONCLUSIONS
Digital processing techniques in the two sites areas, during
1975-1993, highlight the following:
e The available satellite images allow a cinematic
multisensor approach. Landsat-TM and SPOT-HRV
medium scale images ensure a satisfactory level of
accuracy for monitoring changes detection in Danube
Delta areas. Although the Landsat MSS low resolution
images extend study period, they add difficulties during
processing and interpretation of results. In order to
complete information for these images has to be utilized
historical surveys from the same date.
e Applied techniques (preliminary radiometric and
geometric processing, data compression, contrast and
edge enhancement, multispectral classification, post-
classification processing) assured the maximum
accuracy in data processing (without altering the initial
information) and in the results interpretation.
e The use of vegetation indices, merged with principal
component analysis reveals very useful information
regarding the area change percentage for different
vegetation classes from Danube Delta ecosystems in the
two sites.
e Alteration processes caused by antropic interventions in
these areas were depicted: reduce of stagnant water
ecosystem, compactly common reed, forest areas and
increase of mixture common reed-mace reed, uncovered
soil and urban areas (see figure 7) It is obvious the
failure of economic exploit efforts such as fish ponds,
agricultural and forest polders. After 1990, many of
these projects were abandoned and ecological
restoration projects were initiated. Figure 9 presents
ecosystem impact of sand-mining abandoned
construction from Caraorman bank. Even after 10 years
the ecosystem have not restored.
The accuracy assessment resulted in a measure of the quality of
the change information. Such measures are vital when
important natural resource decision is based on satellite-derived
information, as is the case with natural environment of Danube
Delta.
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