MONITORING RAIN AND FLOODING EVENTS IN DE LA PLATA BASIN USING AMSR-E SIGNATURES

FERRAZZOLI, PAOLO; RAHMOUNE, RASHID; GRINGS, FRANCISCO MATIAS; SALVIA, MARÍA MERCEDES; BARBER, MATÍAS; KARSZENBAUM HAYDEE; SOLDANO, ALVARO; GONIADZKI, D; PARMUCHI, GABRIELA; MONTENEGRO, CELINA; KANDUS, PATRICIA; BORRO, MARTA

Ciudad del Cabo, Sudáfrica

Simposio; International Geoscience and Remote Sensing Symposium (IGARSS). 2009; 2009

IEEE

Monitoring extreme variations of soil moisture, eventually associated to flooding, is important for several applications. Long term studies about the water cycle use soil moisture information as an important element. Moreover, severe rainstorms and increases in the water flow of rivers need to be timely monitored, in order to aid the development of an effective protection.It is recognized that passive microwave instruments, operating at the lower frequencies, are very effective for soil moisture monitoring. In these systems, soil moisture is the dominant factor influencing the surface emissivity. Other elements, such as soil roughness and vegetation biomass must be considered in the algorithms but, in most of the cases, are less important than the main effect of soil moisture. For this reason space missions, such as forthcoming SMOS and future SMAP, use L band instruments. Presently available spaceborne radiometers, such as AMSR-E, operate at higher frequencies which are not the most effective ones for soil moisture monitoring. However, some studies aimed at exploiting the use of higher frequency radiometers for this application have been carried out. Results indicate that there is some potential, especially when strong events, associated to flooding or severe rainstorms, are being monitored. Various algorithms have been proposed. In spite of differences in the implementation, the algorithms are based on the same basic properties, confirmed by models and previous experiments. In a soil covered by vegetation, an increase of soil moisture produces a decrease of emissivity which is more evident at the lower frequencies and at horizontal polarization. An increase in vegetation biomass reduces the sensitivity to soil moisture and makes the emissivity less dependent on frequency and polarization.This paper shows the results of a sensitivity study about the effects of flooding and rainstorms on AMSR-E signatures. The study site is the La Plata Basin, covering about 3.6 million km2. In terms of geographical extent, it is the fifth largest basin in the world. The principal sub-basins are those of the Paraná, Paraguay and Uruguay Rivers. The annual mean total precipitation in the De La Plata Basin is about 1,100mm, of which only about 20% reaches the sea as surface water. The other 80% is evaporated and infiltrated into the ground. In particular, we have considered a flooding event which occurred in the middle and low sub-basins of Parana river in February and March 2007, and a severe rainstorm which occurred in the southern side of the Chaco forest in September 2006.