MACHINE LEARNING INTEGRATING CLIMATE DATA WITH GRACE MISSION DATA FOR THE RECONSTRUCTION OF TERRESTRIAL WATER STORAGE ANOMALIES IN BRAZIL.
terrestrial water storage, machine learning, GRACE, climate change
Terrestrial water storage (TWS) is a critical component of the hydrological cycle, directly
influencing water security, energy production, and climate resilience in Brazil. Although the
country has abundant freshwater resources, their uneven spatial distribution combined with
the growing impacts of climate change exposes both the population and the economy to
hydrological risks. The Gravity Recovery and Climate Experiment (GRACE) missions have
provided valuable insights into TWS variability since 2002; however, their limited temporal
coverage constrains long-term analyses. To overcome this limitation, this research
reconstructed terrestrial water storage anomalies (TWSA) for Brazil’s 12 major river basins
from 1985 to 2002, integrating GRACE data with climatic variables (precipitation, soil
moisture, temperature, and teleconnection indices) and anthropogenic indicators derived from
land use and land cover (LULC) data. Two machine learning models—Random Forest (RF)
and Long Short-Term Memory (LSTM)—were implemented and compared to assess
performance, interpretability, and suitability for GRACE-TWSA reconstructions. Results
indicate natural seasonality throughout the year, with vegetation and climate indices emerging
as highly influential predictors of TWSA, while anthropogenic factors affect anomalies
differently across basins, particularly in areas dominated by agriculture and livestock
activities (such as cotton in the Amazon Basin and perennial crops in the São Francisco
Basin). Both RF and LSTM achieved satisfactory performance, though LSTM was able to
reconstruct the time series for only a few basins, while RF provided greater interpretability of
variable contributions. The Mann-Kendall test applied to the RF-reconstructed TWSA series
revealed significant long-term decreasing trends in the Uruguay, Parnaíba, São Francisco, and
East Atlantic basins, underscoring Brazil’s vulnerability to water stress under future climate
scenarios. By extending GRACE-derived observations, this study advances understanding of
how climate and LULC influence TWSA variability and provides evidence to support public
policies for sustainable water resource management in Brazil.
Keywords: terrestrial water storage, machine learning, GRACE, climate change