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15, V. 4, 
Potcoava, Mariana - Camelia 
The using of satellite image data from optic and microwaves data for development of a methodology for 
identification and extraction of flooded area 
Mariana Camelia Potcoava, George Stancalie, Dan Raducanu 
National Institute of Meteorology and Hydrology, 97 Soseaua Bucuresti-Ploiesti, sector 1, 71552 Bucharest, Romania 
e- mails: camel@meteo.inmh.ro, george(@meteo.inmh.ro 
Technical Military Academy, Bucharest, Romania e-mail: danr@yahoo.com 
Keywords: remote sensing, flood extent, flooded vegetation, flood evolution, ERS - 1 SAR, LANDSAT - TM 
ABSTRACT 
A significant number of events that are classified as natural disasters can be attributed to environmental 
mismanagement and degradation. Most natural disasters are localized: flooding is one of these. Investigations have been 
carried out in the south of Romania in some surrounding areas of Bucharest city to assess temporal and spatial surface 
changes of inundated areas with multispectral (LANDSAT - TM) data and multitemporal (ERS - 1 SAR) data. The 
Bucharest city is crossed of the rivers Dimbovita (tributary of the Danube) and Colentina. In generally the floods are 
caused by deforestation and soil erosion. Traditionally, optical remote sensing has been used to provide environmental 
information such as that required for hydrological applications; however, it is often hampered by time-of-day or weather 
constraints. In addition, the restricted penetration of optical wavelengths into volume, such as a vegetative canopy or 
soil, limits the amount of information on hydrological conditions that can be derived from an image. Because SAR is an 
active microwave system it can provide day and night data imaging capabilities, and the low frequencies allow for data 
acquisition in fog and light rain. It is particularly well suited to hydrological applications due to the sensitivity of 
microwave energy to the presence of water. 
The purpose of this paper is to present a methodology to determine the amount of area directly affected by floodwater 
and it show how the combined use of ERS - 1 SAR data and LANDSAT - TM data can contribute towards a deeper 
knowledge of the area under consideration. 
The success of flood monitoring with the optical satellite data mainly depends on the availability of cloud — free images 
during the flood process. The main steps in flood monitoring using optical satellite data are: identifying water bodies 
effectively; eliminating some cloud influences; estimating the area of the flood accurately; and, monitoring the flood 
process dynamically. 
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 for LANDSAT - 
TM data and also ERS - 1 SAR data were analyzed with respect to their potential to derive specific information applied 
to the problem. These informations are introduced into geographic information system to establish hazard maps and risk 
potentialities. 
The results obtained from the remotely sensed data have shown a good concordance with the available " in-situ" data 
implying that remote sensing techniques provide a means for locating, identifying and mapping certain features and 
aspects of flood areas. These informations will be directed to end-users for the surveillance and the management of 
water resources. 
1. INTRODUCTION 
Bucharest city and some surrounding areas, placed at south of Romania is crossed of the rivers Dimbovita (tributary of 
the Danube) and Colentina. A significant number of events that are classified as natural disasters can be attributed to 
environmental mismanagement and degradation. Most natural disasters are localized; flooding is one of these. In 
addition, the connection between deforestation and floods has been known for centuries. In generally the floods are 
caused by deforestation and soil erosion. 
In disaster prevention, risk analysis requires the compilation of a number of information extracted from satellite data: 
land cover mapping, digital elevation model (DEM) generation, soil moisture monitoring, wetland monitoring, snow 
cover mapping, mapping land-water interface, the determination of flood extent, and snow - water equivalent 
determinations. These informations are introduced into geographic information system to establish hazard maps and risk 
potentialities. Remote sensing technique is used on all stages of monitoring: before flooding, during flooding, and after 
flooding. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 1185