Figure 1. Schematic overview of the streamflow mapping procedure.

The procedure consisted of four main steps: 1) monitoring stations (gauges) are geo-referenced based on the global hydrography, 2) catchment-specific covariates are compiled by aggregating climatic and physiographic variables over the upstream catchment of each cell, 3) ANNs are trained on monitoring data of AF metrics and covariates of the corresponding upstream catchment, 4) the trained ANNs are applied to the spatially-continuous covariates to create the global streamflow maps.