Special issue  

Physically based and conceptual models in hydrology are the two endpoints in the spectrum of modelling strategies, mostly differing in their degree of detail in resolving the model domain. Given the limitations both modelling strategies face, we believe that to achieve progress in hydrological modelling, a convergence of these methods is necessary. This would allow us to exploit the respective advantages of the bottom-up and top-down models while limiting their respective uncertainties.

The paper aims to propose a conceptual framework that supports nuanced understanding and analytical assessment of resilience in socio-hydrological contexts. We identify three framings of resilience for different human–water couplings, which have distinct application fields and are used for different water management challenges. To assess and improve socio-hydrological resilience in each type, we introduce a resilience canvas as a heuristic tool to design bespoke management strategies.

In 2009, the "planetary boundaries" were introduced. They consist of nine global control variables and corresponding "thresholds which, if crossed, could generate unacceptable environmental change". The idea has been very successful, but also controversial. This paper picks up the debate with regard to the boundary on "global freshwater use": it argues that such a boundary is based on mere speculation, and that any exercise of assigning actual numbers is arbitrary, premature, and misleading.