Abstract: A survey of research progress on assessment methods for climate change and human activity affecting hydrological factors in separated manner was executed in this study. A novel idea of source attribution was proposed that changes in hydrological processes brought by environmental reasons could be attributed into three sources: climate natural variability, human-induced climate change, and human activity. Thus a framework was presented. Due to the complex uncertainties in the hydrological processes under environmental change, uncertainty factors in hydrological processes were deeply explored, thus common quantitative and qualitative uncertainty evaluation approaches were summarized. Moreover, the Info-Gap theory was addressed to solve the problem of qualitative uncertainty (Knightian uncertainty) estimation. Finally, to enhance the ability of mitigation and adaptation for environmental change, it demonstrates that in future studies on environmental change impacts should be strengthened in terms of climate natural process, human-induced climate change and human activity. Uncertainty analysis should be an original part of environmental modeling rather than additional or dispensable component. In the impact assessing, it suggests that uncertainty estimation should be fully stressed. Further uncertainty information based on catchment-scale risk management should be facilitated in catchment-scale management decision-making.

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