The rivers and lakes dataset used in this video is from BGR WHYMAP (World-wide Hydrogeological Mapping and Assessment Programme), as is the aquifer dataset. The aquifers shown are only a fraction of the world's groundwater resources. They represent the approximately 35 percent of the land subsurface (excluding the Antarctic) that hosts relatively homogeneous aquifers, typically in large sedimentary basins. Less homogenous and minor aquifers are not represented.
The global freshwater storage data come from NASA's GRACE (Gravity Recovery and Climate Experiment), a pair of satellites that detect small changes in Earth's gravity field caused by the movement of water masses on and underneath land surface. Freshwater is sensed not only in rivers and lakes but also in groundwater, soil moisture, snow, and ice. GRACE's monthly images are anomaly maps, showing blue where there is more water than average and brown
where there is less water than average.