Use of Remote Sensing in Monitoring River Floods and their Effects on the Landscape

  1. I. Peter Martini2,
  2. Victor R. Baker3 and
  3. Guillermina Garzón4
  1. L. Halounová

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304299.ch15

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

How to Cite

Halounová, L. (2002) Use of Remote Sensing in Monitoring River Floods and their Effects on the Landscape, in Flood and Megaflood Processes and Deposits: Recent and Ancient Examples (eds I. P. Martini, V. R. Baker and G. Garzón), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304299.ch15

Editor Information

  1. 2

    Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada

  2. 3

    Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721–0011, USA

  3. 4

    Dpto de Geodinámica, Fac. de Geología, Universidad of Complutense, 28040 Madrid, Spain

Author Information

  1. MGE DATA, Vrchlického 60, Prague, Czech Republic

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 10 FEB 2002

ISBN Information

Print ISBN: 9780632064045

Online ISBN: 9781444304299

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Keywords:

  • use of remote sensing in monitoring river floods and their effects on landscape;
  • study design and methods;
  • detection of flood under forest canopy;
  • procedure for estimating effects of river floods in large areas utilizing remote sensing satellite data;
  • satellites equipped with radar sensors - ERS (Europe) and RADARSAT (Canada);
  • RADARSAT images with descending orbit in South Moravia;
  • flood effects on agricultural areas

Summary

Intense rainfall caused extensive flooding in the eastern part of the Czech Republic in July 1997. On 4 July 1997, a low-pressure system originating in northern Italy tracked north-east to the Moravia region of the Czech Republic bringing intense rainfall as it moved to the south-east of Poland and Silesia on the morning of 6 July. Over a 5-day period, 500 mm of rain fell over one-third of Moravia (10 000 km2). The average rainfall for the Czech Republic is 600 mm yr−1 (Halounová et al., 1999). The region of South Moravia was imaged three times by the RADARSAT satellite: one image was taken at the flood peak, one image after the peak, and the last one at the end of the flood. These radar images allowed detailed monitoring of the flood and its effects. The flood-peak image was used for choosing flooded areas in an agricultural region. Each flooded ‘area’ was part of a larger ‘field’; that is, of a parcel of land delimited by natural or manufactured features visually recognizable on available SPOT and Thematic Mapper images and on the peak-flood RADARSAT image. Flood-induced changes to the land surface could be detected by comparing the backscatter mean values of areas with those of their associated fields and by considering the fields and areas backscatter standard deviations measured on the peak-flood image and two subsequent RADARSAT images taken during flood recession. This could be done because of the peculiar characteristics of radar images. Radar backscatter values are influenced mainly by surface roughness (the higher the roughness the higher the backscatter) and by moisture (the higher the moisture the higher the backscatter). Depending on the backscatter mean values of areas and their respective fields in the various images, it was possible to reconstruct events during the flood in that region. For example, if the post-peak flood surface of a given area was smoother (lower mean backscatter) than its field, it was a zone of sedimentation. If the surface roughness (similar backscatter) was the same in an area as in its field, nothing had changed. If the surface was rougher in the area than in the field, it may be attributable to erosion or sedimentation of coarse material. These conclusions were validated by using the standard deviation values of the backscatters of the fields. This novel method of analysis is effective in studying open terrains, such as agricultural lands, but cannot be used in forested lands. There the flood delineation can be carried out only at the moment of imaging: flooded forest backscatter mean values are generally higher than non-flooded forest backscatter mean values.