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River Mapping from Satellite Radar Altimeter Sigma0
Bramer, S1; Berry, P.A.M2
1De Montfort University; 2EAPRS labaratory

The ERS1 Geodetic Mission yielded a unique closely spaced mesh of measurements over the Earth’s land surface. This unique dataset contains echoes obtained over inland water, with very dense spatial sampling along river courses. However, interpretation of these data is problematic, since environmental events also cause ephemeral bright targets to appear on the Earth’s surface; also the sigma0 response over rivers is extremely variable, affected by surface roughness, off-ranging and the spatial extent of the flooded surface. Using an expert system approach to recalculate sigma0 and screen the echo shapes, a methodology has been designed to create detailed sigma0 maps from these data, supplemented by ERS-2 data. Whilst this approach was initially developed to generate accurate sigma0 maps of desert regions for calibration purposes, the techniques for removal of environmental contamination have proved so effective that it has been possible to apply this technique over major river basins, obtaining precise maps of these river system locations. This paper presents results from this modelling approach, showing sample river networks together with comparisons with ground truth. This work demonstrates the extent to which pulse limited altimeters can retrieve inland water signatures over river networks and gives a valuable insight into the untapped potential of radar altimetry for river monitoring.

 

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