Annual and seasonal water storage changes detected from GRACE data in the La Plata Basin

Abstract

The gravity does not remain constant, but changes over time depending on the redistribution of the masses. Aquatic environments, like a river basin, perform important functions in nature such as control of climate, floods and nutrients; and they also 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. The La Plata Basin is the second largest in South America and is a sample of the abundance, variety and quality of natural resources and possibilities offered in connection with the production of goods and services. The objective of this work is to analyze GRACE capability to monitor the water storage variations in the La Plata Basin. Firstly, GRACE solutions from four different processing centers are used to estimate the gravity trend and gravity amplitude over this basin. Afterwards, the calculated hydrological signal is used to obtain mass change models over this hydrographic system´s area, using two different methods and for the period from 2002 to 2009. Next, the annual and seasonal water storage changes from GRACE solutions are validated in Argentina by rainfall data over the time periods where extreme weather conditions took place. The results indicate that GRACE detected the variations of the continental water storage in the La Plata Basin, and particularly, it detected the important decrease in the South of the basin. Moreover, a coherency between the estimates of water mass changes and rainfall data was found, which shows that GRACE also detected extreme weather events (such as drought and intense rain episodes) that occurred in the 2004-2009 period in Argentina.