~ 1592 ~ Journal of Pharmacognosy and Phytochemistry 2018; 7(4): 1592-1595 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2018; 7(4): 1592-1595 Received: 01-05-2018 Accepted: 05-06-2018 Sunil Kumar Yadav Department of Environmental Science & Nrm, College of Forestry Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India Satyendra Nath Department of Environmental Science & Nrm, College of Forestry Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India Shweta Gautam Department of Environmental Science & Nrm, College of Forestry Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India Correspondence Sunil Kumar Yadav Department of Environmental Science & Nrm, College of Forestry Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India Analysis of rainfall variability in western Rajasthan, India Sunil Kumar Yadav, Satyendra Nath and Shweta Gautam Abstract An attempt has been made to study the rainfall variability analysis of western districts of Rajasthan. Study was performed on data sets of annual rainfall for the period of1986-2016 (31year) for western districts of Rajasthan. The coefficient of variation and standard deviation for weekly, monthly and annual rainfall were also computed for selected districts. The normal onset of monsoon over different western districts of Rajasthan is between June to October. It was found that the annual rainfall is higher at Sikar district followed by Jalor and Pali. The mean annual rainfall is lowest at Jaisalmer. When the CV for the annual rainfall was examined, it was found be the least at Churu followed by Bikaner, Ganganager and Barmer it was the highest. Keywords: Rainfall variability estimation western rainfall variability analysis of western districts Introduction Western Rajasthan comes in arid western plain and Thar Desert. The soils of this zone are predominantly Sand soil, desert soil, aridisol and andisol group. These are generally Sand loam intexture. The mean annual rainfall is 350 mm. The mean dailymaximum temperature at Western Rajasthan form 24.5°C in January to 45.5°C in May. Similarlythe mean daily minimum temperature ranges from 8.6°C in January to 29.7°C in May. Theprincipal crops of the zone are pear millet, cluster bean, moth bean, chick pea, wheat and fruit crop ber, aonla, pomogrante, dateplam. Rainfall is one of the most importantnatural resource input to crop production in the Western region. Rainfall characteristics Rainfall variability of twelve districts (Sikar, Pali, Nagaur, Jodhpur, Jhunjhunu, Jalore, Jaisalmer, Ganganager, Churu, Bikaner, Barmer and Hanumangarh) of arid western Rajasthan during the period 1986-2016 (31year) was computed from available daily rainfall data recorded at rain-gauge stations of the district. The data were downloaded from the web site (www.waterresources.rajasthan.gov.in,) for further scrutinized and checked for their use in the present study. Mean rainfall The amount of rainfall collected by a given rain gauge in 24 hrs is known as daily rainfall (mm or cm) and the amount collected in one year in known as annual rainfall. The mean of the annual rainfall was calculated by given formula Mean Annual Rainfall =      Standard Deviation (SD) It is defined as the square root of the mean of the squares of deviations of the rainfall value from the arithmetic mean of all such rainfall. It is a measure of variability or the scatter or the dispersion about the mean value. It is given by the following formula. X = Rainfall   = Mean rainfall n = Number of year