HYROLOGICAL IMPACTS OF CLIMATE CHANGE - CHALLENGES, UNCERTAINTY AND LIMITATIONS

摘要

How climate change impacts water resources in the future is an important question that all hydrologists want to have an answer to. Climate projection scenarios are available from many Global Circulation Models. These projection datasets are typically used as input to a hydrological model for simulating impacts on hydrology, particularly river runoff, evaporation, and storage changes. However, there are a number of uncertainties (e.g. choice of a GCM, downscaling model, etc.), which make the impact assessment process complicated and heavily restrict our ability to make predictions of hydrological impacts. We illustrate some of these issues and their impacts on hydrological simulations using two examples from the Himalayan region: the Koshi River basin, Nepal and the Yellow River source region, China. Climate projections used are from a number of GCMs participated in the Coupled Model Intercomparison Project (CMIP3). In both examples, detailed process based distributed hydrological models are used. Overall, we conclude that an assessment of climate change impacts based on only one GCM, one downscaling model or one emission scenario should be interpreted with caution.