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Analysing the Variability of Rainfall for Drought Progonosis in Jharkhand State: A Statistical Approach
Author(s) -
Pandey Swati,
Kumar Manoj,
Chakraborty Soubhik,
Mahanti N. C.
Publication year - 2011
Publication title -
irrigation and drainage
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 38
eISSN - 1531-0361
pISSN - 1531-0353
DOI - 10.1002/ird.627
Subject(s) - monsoon , precipitation , mathematics , negative binomial distribution , statistics , probability distribution , distribution (mathematics) , sowing , conditional probability , environmental science , hydrology (agriculture) , geography , meteorology , agronomy , engineering , biology , poisson distribution , mathematical analysis , geotechnical engineering
ABSTRACT Agriculture in the state of Jharkhand depends on the southwest monsoon which brings about 80% of the mean annual precipitation. The high variability in rainfall generally leads to meteorological drought conditions, demanding a large time domain analysis of rainfall behaviour. In the present paper, daily rainfall data for 49 years (1956–2006) of Ranchi District, Jharkhand state of India, were analyzed for the probability and variability of rainfall. The monsoon weeks, i.e. the 21st to the 41st, were considered and it was found that the rainfall distribution can be modeled by a negative binomial distribution. Additionally, by denoting a wet week by W and a dry week by D, the unconditional probability P (W) and the conditional probabilities P (W/W) and P( W/D) for these weeks were evaluated using a first‐order Markov chain at three probability levels (30, 50 and 70 mm). The results were checked against a uniform model with the help of the Kolmogorov‐Smirnov test and it was found that in most cases they supported the uniform distribution assumption. Lower probability (less than 0.50) of getting 70 mm of rainfall under any probability conditions during the 27th to 38th weeks indicated the proneness of the region to drought during the crop growth and maturity stage under condition of initial rainfall failure during the crop sowing stage. Copyright © 2011 John Wiley & Sons, Ltd.