Regionalization of Rainfall in Kerala State

The main objective of this study is to classify the entire State of Kerala into optimum number of homogeneous zones based on monthly rainfall. The same is done by Ward's Clustering method by taking the monthly rainfall data for five consecutive years from 2008-2012 of 63 raingauge stations in Kerala state. Clustering is the process of dividing the area under consideration to a limited number of climatologically homogeneous zones, based on any hydrologic parameter. The purpose of cluster analysis is to place objects into groups suggested by the data, so that objects in a given cluster tend to be similar to each other and objects in different clusters tend to be dissimilar. It is found that the region can be grouped into seven clusters. There exists large variability in average annual rainfall of different clusters. There are cluster groups where the annual rainfall is as high as 1.5 times and as less as half of average annual rainfall of Kerala as a whole.