Statistical downscaling of GRACE gravity satellite-derived groundwater level data

With the continued threat from climate change, population growth and followed by increasing water demand, the need for hydrological data with high spatial resolution and proper time coverage to be felt more than ago. Therefore, having data such as terrestrial water storage changes and groundwater level changes with high resolution spatial helps to plan and make decisions for water resource management more efficiently. Since the beginning of the GRACE mission, evaluation of water resources, especially groundwater level changes has been provided at a global scale. Despite the wide coverage area, due to the low spatial resolution and large pixel size (~200,000 km2), the use of GRACE data for local and smaller scales, it isn’t possible. Therefore, the purpose of this research is the feasibility of downscaling GRACE data to small and local scale. In this study, used from an empirical regression method based on the relationship between GRACE and other hydrological data and created groundwater level changes data with 0.25 degree gridded. Finally, used from groundwater level changes data derived from monitoring wells to validate downscaled groundwater level changes, where RMSE value between 38.17 mm to 56.4 mm, and R2 between 0.49 to 0.54 were obtained. Therefore, this method can improve GRACE data resolution from 1° to 0.25°, effectively.