Seasonal variations in terrestrial water storage can be computed with the water-balance method using three main variables: the water vapour flux convergence, the precipitable water content, and river runoff. The two first variables are available with high resolution and good accuracy in present reanalysis data, and river runoff is commonly measured in most parts of the world. A case study for the Mississippi river basin shows that this method can provide reliable estimates of monthly changes in terrestrial water storage (see paper J3.18).

Here we present computed estimates of seasonal changes in terrestrial water storage for various major river basins in Europe and Asia. The employed data include ERA-40 reanalysis data from the European Centre for Medium-Range Weather Forecasts (atmospheric water vapour flux and precipitable water content) and conventional runoff measurements. When available, comparisons with soil moisture measurements are presented.