A Belgian Water Forecast

摘要

Climate change is often discussed in global terms. However, responding to and planning for it requires extending global models to the local level, and assessing impacts on a variety of lo- cal resources, such as ecosystems or seasonal water supply that may have a complex response to the main vari-ables, such as temperatun and precipitation. Many uncertainties are associated with such downscaling, regarding how to extend the models and how to assess the local variability in, for instance, precipitation in a future climate. However, approaches are increasingly being developed to consider and explore these uncertain- ties explicitly, as well as to incorporate ranges of future variability into planning both in the near term and for longer periods. Goderniaux et al. illustrate such an approach for assessing the future of groundwater resources in the Geer Basin in Belgium, an important local source of drinking water. In their approach, the authors use the relative change between two global and six regional models, rather than the absolute predicted climates, to build up a stochastic set of future records in key parameters affecting the hydrology of the basin. This allows a probabilistic assessment that can more explicitly represent uncertainties for managers. Overall, they suggest that the climate change signal may dominate normal variability by the later part of this century. Mean groundwater levels are projected to decrease by about 10 m.