Derivation of the relative contributions of the climate change and human activities to mean annual streamflow change

Both climate change and anthropogenic activities are known to induce streamflow change. It is important to understand how it works. Here we integrate the long-term water balance equation with the Budyko framework to analytically attribute the mean annual streamflow change to changes in precipitation and potential evapotranspiration caused by climate change, and to changes in watershed properties caused by anthropogenic activities. The attribution approach is applied to six sub-basins in Mekong River basin as a case study for attributing the decadal change in streamflow during 1960–2018 over the baseline (1960–1969). Results indicate that the observed streamflow decadal changes are mostly due to anthropogenic activities with some decadal contributions from changes in precipitation. The rapid rate of water infrastructure (e.g., dams) development has been reported there. The streamflow record and the attribution approach described here can be used to explicitly unravel the climatic and anthropogenic drivers of the hydrologic cycle.