RAINFALL CHARACTERISTICS AND METEOROLOGICAL DROUGHT IN HANUMANGARH DISTRICT OF ARID RAJASTHAN

Abstract

The rainfall characteristics and meteorological drought conditions in Hanumangarh district of arid Rajasthan were studied using seven tehsil-wise rainfall data (1960-2012). The district experiences 225 to 371 mm of annual rainfall in 12 to 19 rainy days. The resultant standard deviation of annual rainfall was 104 to 171 with a coefficient of variation of 39 to 48 per cent. The seasonal rainfall (June-Sept.) varied from 170 to 309 mm in 10 to 15 rainy days. The highest annual rainfall recorded in the district was between 460 mm at Pilibanga and 887 mm at Bhadra. Similarly, the lowest rainfall record varied between 22 mm at Hanumangarh and 111 mm at Bhadra. The extreme rainfall events recorded in the Hanumangarh district showed that 1-day highest rainfall varied from 122 mm at Bhadra to 175 mm at Pilibanga. The 1-day rainfall was lowest at Sangaria (72.7, 88.3, 107.8, 122.3 and 137.1 mm) and highest at Nohar (90.6, 107.9, 129.4, 145.4 and 161.8 mm) for all return periods (5, 10, 25, 50 and 100 years). The long-term annual rainfall trends showed that there was a increase at a rate 1.12 mm year -1 at Hanumangarh, 2.24 mm year -1 at Tibi, 2.42 mm year -1 at Sangaria, 0.60 mm year -1 at Nohar, 1.00 mm year -1 at Bhadra and 1.41 mm year -1 at Pilibanga. The meteorological droughts prevailed in 17 years out of 53 years (1960-2012) with lowest frequency of 16 years with drought at Bhadra, Sangaria and Nohar to a highest frequency of 18 years drought at Hanumangarh. The decade 1960-69 experienced highest (5 out of 10 years) number of moderate to severe droughts, whereas the 2001-2012 recorded least frequency (2 out of 10 years) of droughts. Similarly using Standardized Precipitation Index (SPI), an analysis on incidence and severity of drought occurred in Hanumangarh district during the period 1960-1969 (7 out of 10 years) and 1980-1989 (5 out of 10 years) experienced highest number of moderate and severe droughts.