Water Storage Changes from GRACE Data in the La Plata Basin

AYELEN PEREIRA; SILVIA MIRANDA; MARÍA CRISTINA PACINO; RENE FORSBERG

Ciudad de Buenos Aires

Otro; Asamblea Científica de la IAG (International Association of Geodesy): Geodesy for the Planet Earth; 2009

International Association of Geodesy (IAG)

Aquatic environments perform important functions in nature such as the control of climate, floods and nutrients, and they provide goods and services for humanity. To monitor these environments at large spatial scales, the satellite gravity mission GRACE provides time-variable gravity field models that reflect the Earth´s gravity field variations due to mass transport processes like continental water storage variations. GRACE can map water storage changes to heights of a few millimeters on a spatial resolution of 400 km. The La Plata Basin is one of the largest in the world with an area of 3,100,000 km2, which is equivalent to the 17% of South America´s area. This basin covers 5 countries: Brazil, Argentina, Paraguay, Bolivia and Uruguay. The main rivers in Argentina that are part of this hydrographic system are the Paraná (its basin is the biggest one with an area of 1,510,000 km2), Uruguay and Paraguay. Also in the La Plata basin lies a big part of the second fresh groundwater reservoir of the world (the Guaraní Water-bearing System), thus knowing its behavior is of extreme importance for being a great environmental, economic and strategic resource. Temporal and spatial variations of water storage in the area covered by the basin are difficult to measure using ground data because of the hydrographic system´s size; but with the present advance of technologies represented by GRACE data it is possible to detect the monthly spatial changes in the distribution of water masses in these regions. The aim of this work is to show the temporal variation of water masses detected over the La Plata basin, provided by four different GRACE processing centers: CSR, JPL, GFZ and BGI. The changes of superficial and underground water masses for the period 2002- 2008 are analyzed. The time series of water storage variations from GRACE and ENVISAT are shown together with the corresponding trend maps. Also, preliminary results from the NASA monthly mass grids are presented.