Potcoava, Mariana - Camelia 
  
Before of flooding we observe the " smooth dynamics, the long-term trends within the ecological nonstable areas, and 
compile the maps of risk of ecological hazards (permanent water bodies, landscape morphology derived from DEM). 
During of flooding we detect accidents and survey the areas subjected to disasters with minimal time lag (flood extent 
derived from 1 image and flood evolution derived from n images). 
After of flooding we survey the sequences of disaster, volume of damage (destroyed areas, deposits and debris), and 
effects of restoration. 
Identification of the surfaces occupied with water by means of mean and high resolution satellite images data is 
necessary for many studies concerning the surface hydrology as well as the issues of the water pollution. 
2. METHODOLOGY 
The purpose of this paper is to present a methodology to determine the amount of area directly affected by floodwater. 
This methodology employs change detection requiring a base image data set and an image during the flood period. This 
main task is based on the conception and development of remote sensing techniques for the study of multispectral, 
LANDSAT - TM data and multitemporal, ERS - 1 SAR data. 
The acquisition of the cartographic data and the elaboration of digital maps concerning the landcover elements were 
made under ARC/INFO software environment. 
The mathematical approach deals with first identifying which image bands relate best toward solving the environmental 
hazards problem and secondly determining how mathematically to merge spectral bands into one final image from 
which the needed information can be obtained. 
Additionally multitemporal enhancement techniques were analyzed with respect to their potential to derive specific 
information applied to the problem. 
3. DATA 
For realize this study had been used two dataset image data from optic and radar ranges: LANDSAT TM 1,2,3,4,5,7 , 
1024x1024 size, 30x30 m pixel size, from 08 August 1991 and ERS -1 SAR scenes from 3 June 1992 - Bleu, 25 
November 1992 - Green, and 30 December 1992 - Red (cover the representative test area, Bucharest city). 
Topographical maps at 1: 10000 scales were used for locating ground checks and identifying sample areas for 
corresponding digital analysis. Digital data were used for digital analysis under ERDAS - PC version environment. 
4. PREPROCESSING OF THE DATA 
The first problem to be addressed was the creation of an integrated multisensor dataset. As the ground reference 
information was recorded in map form, the decision was made to rectify all imagery to that map grid, namely, a 
stereographic projection. 
Because of the presence of significant geometric distortions due to topographic relief the airborne SAR and LANDSAT 
were resample to LANDSAT - TM pixel size by the nearest neighbour method and furthermore geocoded to a 
topographical map of 1: 10000. 
  
Figure 1. Topographical map, Colentina River (representative area) 
  
1186 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.