ABSTRACT
From the standpoint of evaluating the availability of water resources, precipitation characteristics of interest are intensity, amount, and duration of occurrence. Entropy can be employed to determine the uncertainty associated with any of these characteristics. If pi > 0 is the probability of the ith precipitation event (e.g., amount, intensity, or duration), then the Tsallis entropy Sm (Tsallis, 1988) can be expressed as
S m
= -
-( )- =
å1 1 1 1 1
(9.1)
where N > 1 is the number of events m is the Tsallis entropy parameter
Let the total amount of precipitation over a certain period of time (say day, week, or month) or simply precipitation intensity (amount per unit time) be a random variable. Then, its probability distribution can be derived from data and its entropy can be calculated. The entropy so obtained is referred to as “intensity entropy (IE).” IE can be evaluated as follows (Maruyama et al., 2005):
1.Obtain precipitation data available at a rain gauge. If data are available for M years and intensity is defined on a monthly basis, then the number of monthly intensity values would be 12 × M = N. All monthly precipitation data of the M-year record are considered as one data set without any consideration of sequence or chronology.
