MONITORING DE LA PLATA BASIN USING PASSIVE AND ACTIVE MICROWAVE INSTRUMENTS

MOCCIA, FERNANDO; SALVIA, MARÍA MERCEDES; FERRAZZOLI, PAOLO; KANDUS, PATRICIA; KARSZENBAUM HAYDEE; GRINGS, FRANCISCO MATIAS; PARMUCHI, GABRIELA; SOLDANO, ALVARO

Boston, MA, EEUU - IGARSS'08

Simposio; International Geoscience and Remote Sensing Symposium (IGARSS). 2008; 2008

IEEE

An   important   application   of   microwave   remote   sensing   is   the   monitoring   of   floods,   due   to   river   inundation   or   severe rainstorms. Several papers investigated the potential of passive and active systems in this application. Passive systems are more suitable to large scale studies, while active systems (particularly SAR’s) are more useful when a good spatial resolution is required. In this work, both passive and active signatures collected within the De La Plata basin are analyzed.The De La Plata Basin is located in South America and covers about 3.6 million km2. It is the fifth largest basin in the world with extensive and important native forest, very productive agricultural areas, wetlands, important human settlements and infrastructure developments. The principal sub­basins are those of the Paraná, Paraguay and Uruguay Rivers.  International projects addressing the hydroclimate of the basin, such as La Plata Basin (LPB) project [1], are right now in progress. Also, several projects addressing smaller areas within the basin are currently in progress related to radar remote sensing in wetlands, and more recently an ESA AO project related to data exploitation of forthcoming SMOS satellite has been accepted.Within this frame, this paper investigates the contribution of passive microwave measurements from the AMSR­E radiometer acquired over the whole basin and data from ENVISAT ASAR obtained over part of the Paraná sub­basin during the summer of 2007 in occasion of strong flooding in the area.  A multitemporal analysis of AMSR­E signatures, covering a time interval between May 2006 and the end of 2007 was carried out. In particular, maps based on the normalized polarization index (PI) at C band and the normalized frequency index (FI) at C and Ka band were produced. These indexes are not dependent on surface temperature. The study was carried out over the whole basin, including the large Chaco forest. Information about fundamental variables, such as biomass of this forest was available to us. Along the Paraná river, multitemporal PI images show wide regions characterized by higher PI values, related to   flooding.   The   spatial   and   temporal   extent   of   these   effects   is   related   to   rain   intensity   and   duration,   velocity   of flooding, channel and floodplain morphology. Within the Chaco forest, a strong rainstorm produced an appreciable increase of PI and FI also in developed forest areas. This result can be important, since the problem of forest opacity receives much attention at present time. Moreover, this paper presents the results obtained in the analysis of two Wide Swath Mode ASAR images collected over the terminal part of the Paraná sub­basin, which was already studied in the previous years by using several satellite data sets. The images were acquired before and after the flooding event occurred during the summer of 2007 when extensive areas dedicated to agriculture and cattle raising were under water. A land cover map obtained with data from the argentine satellite SAC­C operating in the optical region is used as a base map for identification of flooded and non flooded areas. As a result a map of the inundation extent by cover type was obtained.Monitoring   the   De   La   Plata   floodplain   inundation   dynamics,   Chaco   forest   phenology   and   Paraná   sub­basin   wetlands condition   using   passive   and   active   microwave   data   constitutes   the   specific   aspect   of   this   work.   Experimental   data   of backscattering coefficient, emissivity and their temporal variations are interpreted by means of available information about hydrology, meteorology, land cover, and vegetation characteristics of the basin.