Abstract
Abstract. This paper describes a procedure to estimate both the fraction of flooded area and the mean water level in vegetated river floodplains by using a synergy of active and passive microwave signatures. In particular, C band Envisat ASAR in Wide Swath mode and AMSR-E at X, Ku and Ka band, are used. The method, which is an extension of previously developed algorithms based on passive data, exploits also model simulations of vegetation emissivity. The procedure is applied to a long flood event which occurred in the Paraná River Delta from December 2009 to April 2010. Obtained results are consistent with in situ measurements of river water level.
Highlights
Over the past decade, several flood monitoring/forecasting methodologies, based on remote sensing data, have been proposed
A land cover map is shown in Fig. 1, in which the locations of the five water level stations considered in this paper are indicated
The corresponding six AMSR-E dates were selected in order to be as close as possible to ASAR ones, with the further condition to be separated by multiples of 16 days, which corresponds to the repeat orbit
Summary
Several flood monitoring/forecasting methodologies, based on remote sensing data, have been proposed. Passive microwave techniques, characterized by low spatial resolution and high temporal resolution, can provide rough estimates of flooded fraction in certain floodplain regions with virtually no ancillary data (Sippel et al, 1994). Flooding reduces the surface contribution, due to the decrease of roughness, and increases the double bounce effect in vegetated areas. Using physical hypotheses about the emissivity of water and vegetation, this algorithm estimates the fraction of flooded area of a pixel as a function of the absolute polarization difference ( T ) at a given frequency. The fractional flooded area is estimated using linear mixing models that account for the microwave emission of the major land covers within the subregion (Sippel et al, 1994) This algorithm was tested using Ka band of SSM/I system.
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