This study investigates the dominant component of terrestrial water storage (TWS) and its contribution ratio at both seasonal and interannual time-scales on a global-scale, using a land-surface hydrological model, and estimates the climatological mean mass changes. The largest annual range of the four components of TWS, namely soil moisture, snowpack, river channel water storage, and shallow groundwater storage, and the range ratio of the largest annual range among the four components to that of TWS at both seasonal and interannual time-scales on a global-scale are investigated using the land-surface hydrological model. Although soil moisture covers most areas as the largest annual range at the monthly time-scale, the three other components show unique geographical distributions. At the interannual time-scale, geographical distribution is basically similar to that of the monthly time-scale except for the replacement of snowpack to soil moisture in high latitudinal regions. These results provide qualitative information about which component is important for a certain region. In addition, mass changes, namely mineral dust and sediment transports as natural phenomena, crude oil, coal, and natural gas, iron, and bauxite mining as anthropogenic phenomena, are estimated. Comparison of the mass changes with the TWS variability show that it takes a long time for the mass changes to become equivalent to the interannual variability of TWS in magnitude in most regions or fields. Detectability of the mass changes by a satellite gravity mission is examined and the mass decreases due to mineral dust and sediment transports and mining are detectable in regions with large signals within 20 years under ideal conditions. These results provide basic but new information about hydrological features of TWS and mass changes. Copyright © 2012 John Wiley & Sons, Ltd.