Abstract

Global perspectives on the complexities of environmental change impacts associated with past and present
human activity are needed for the food and water security challenges of the twenty-first century. This is
especially true for rivers, for which the onset and persistence of a range in human activities, altering their
function and form, have been temporally and spatially variable. Ancient civilisations, states and empires
extended geographically to cover sub-continental areas where their river modifying activities became linked
to regional Earth system stresses arising from climate and land use change. We present a new interpretative
framework for characterising and classifying human impact on river systems, emphasising that this has taken
place over decadal to millennial time periods on a sub-continental scale. This 16-element classification and
documentation of different human transformations, including land management, urbanisation, industry and
engineering activities, is used to explore anthropogenic channel and floodplain disruptions that have followed
each other in different sequences in different places. It is significant that these inadvertent and deliberate
human interventions have also taken place in parallel with contrasting climatic fluctuations that have been
sub-continental in scale and varied in time. We assess the influence of the dominant modes of regional climate
variability (monsoons, El Nin˜o Southern Oscillation, Indian Ocean Dipole, North Atlantic Oscillation, Pacific
Decadal Oscillation and Siberian High) on the speed and pattern of river system adjustment to anthropogenic
perturbations. Some river civilisations have proved resilient to change given their adaptive management,
while others have been overwhelmed by climate-related changes in river morphodynamics. We conclude
that integrated socioeconomic, climatic and hydromorphological histories provide usefully instructive
antecedents for sensibly managing, as they evolve, the even more serious coupled environmental stresses
likely in the future.