Transboundary river floods: examining countries, international river basins and continents

The objectives of this study were (1) to quantify river floods shared by more than one country, that is, transboundary river floods and (2) to grasp more fully the degree of vulnerability of people to such events on a global, international river basin (IRB) and country level. To these ends, publicly available data were combined to identify such events and the resultant losses of life, flood-related affected individuals and financial damage statistics were related to national levels of development. It was determined that in the period 1985–2005, some 175 of the 1,760 river floods were transboundary, but globally accounted for 32% of all casualties and almost 60% of all affected individuals, illustrating the massive impact of shared floods. This database of transboundary floods was then merged with socio-economic and biophysical data, enabling analyses that revealed the degree of vulnerability of people to transboundary floods from a global to a country level. Selecting one country, continent or IRB most vulnerable to transboundary floods proofed to be unfeasible since the answer heavily depended upon the specific definition of vulnerability, illustrating the complexity of this phenomenon. However, together, the results significantly increased our current knowledge of shared floods which could aid policy-makers in identifying and evaluating potential vulnerability to transboundary river floods.