Abstract:
Rainfall plays a vital role in hydrology, because all hydrological processes are directly related to rainfall. To study the hydrological problems of a region, a hydrologist focuses his attention on the study of characteristics of rainfall in the
region as it is the basic input to the system. Rainfall is a unique phenomena varying in space and time due to several factors like topography, nature of weather system, geography, aerosol content in the atmosphere and drop size distribution in clouds etc. The level of rainfall varies from place to place depending on local topography and is affected by wind fluctuation, orientation of hill 'slope with respect to wind flow etc.
In this technical note characteristics of rainfall have been discussed in four meteorological sub-divisions which cover the regions of seven states of North East India and the regions of Sub-Himalayan West-Bengal and Sikkim. Studied of characteristics of rainfall in Brahmaputra valley and Kulsi Basin are also included in this technical note, because the catchments of Brahmaputra valley and Kulsi basin are hydrologically important in North-East India.
The rainfall data and other informations have been collected from various journals/reports and the characteristics of rainfall have been discussed over the regions (as mentioned above) of North-East India.
