Estimation of world water resources under a changing climate is a key scientific issue for many environmental research areas with
profound socio-economic significance. A new purely data-based scale-extrapolation method is proposed, to estimate water resources
for a large region solely from selected small river basins, which are typically two-orders-of-magnitude smaller than the large region.
Those small river basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics
for the large region. The new method will be validated in both data-rich and data-poor regions, and will be compared with model
estimations. The new method will be applied to 1) generate spatially and temporally complete water recourse datasets for Europe
and Africa, by filling data for un-gauged basins and un-gauged time periods; 2) study interaction between hydrology and climate for
large river basins in Europe and Africa; 3) study the climate change impact on water resources on European and African continents.
Publically available global climate and hydrology datasets will be used to develop the method and allow other researchers to easily
try the method. Current water resource estimations rely on computer models and are subject to model uncertainties. The new
scale-extrapolation method makes it possible to utilise data from a multitude of readily available small basins for robust water
resource estimations under a changing climate.