The East, Southeast and South parts of Asia are also collectively called "Monsoon Asia". This region is generally more humid and rainy than other regions, but also has larger range of dryness and wetness according to seasonal cycle as well as according to interannual variation. The human society of this region has both kinds of problem related to water: too little water (droughts) and too much water (floods).

Variations in the hydrological cycle of this region consist of phenomena of various temporal and spatial scales and interactions among them. In terms of time scales, the annual cycle (seasonal variation) is of course important. Moreover, particularly in the tropics, the diurnal variation and so-called "intraseasonal variations" (variations which have time scales of 10 to 60 days) are also important.

As a basic research towards reduction of drought hazards, we make efforts to grasp the intraseasonal variations in the global scale on one hand, the distribution of precipitation in the local scale (spatial scale generally smaller than 100 km) which is affected by topography and diurnal-cycle variation on the other hand, and how the latter behaves in accordance with the former.

Also, as a basic research towards reduction of flood hazards, we make efforts to grasp local-scale precipitation accurately by integration of observational data from radars and raingauges, and then to develop techniques to predict river flow by feeding the information of precipitation to hydrological models.