Global Assessment of Hydrologic Alteration (Grill et al. 2019)

Global-scale assessment mapping the degree of flow regulation and hydrological alteration across 12 million river kilometres worldwide. Published in Nature, this study found that only 37% of rivers longer than 1,000 km remain free-flowing — the rest are fragmented or have their flow regimes significantly altered by dams, abstractions, and other infrastructure. Uses the Connectivity Status Index (CSI) combining flow regulation (dam storage relative to discharge), fragmentation (longitudinal connectivity), and other anthropogenic pressures. Provides essential continental and global context for interpreting local IHA results from the Incomati Basin, showing how the basin's flow alterations compare with global patterns. Directly relevant to understanding the cumulative impacts of multiple dams and abstractions on transboundary river systems.