Climatic variability over the 20th century and future drift during wheat (Triticum aestivum) growing period in Uttarakhand region, India

An effort was made to analyze the spatial and temporal variability of rainfall and temperature in 13 districts of the Uttarakhand, India over the period of 102 years (1901–2002). The main focus was to examine the rainfall variability and its future response during wheat crop period (November-April). Mann–Kendall test and Sen's slope estimator test used to detect monotonic trend direction and magnitude of change over time on annual and seasonal basis. The Pettit-Mann–Whitney test applied to detect the change points over the century. Mean annual precipitation varied from 821 mm (in Haridwar) to 1244 mm (in Pithoragarh) whereas it was 75 mm (in Udham Singh Nagar) to 178 mm (in Pithoragarh) during wheat growing period. During the wheat crop period, annual precipitation decrease was noticed in Udham Singh Nagar (-37.1%) which was maximum. Maximum decrease in minimum and maximum temperature during wheat growing period and annual period was observed for Uttarkashi district which was -39.4%, -28% and -25.1%, -21.1%, respectively. Similarly, Champawat was second after Udham Singh Nagar having highest temperature in both the periods. The most affected year of change was 1978 and 1940 in annual precipitation and maximum, minimum temperature, but during wheat growing period it was observed in 1945 and 1978, respectively. Mann Kendal trend test shows decrease in precipitation for all the stations during wheat growing period and annual period. In case of annual minimum temperature, average change was 0.0040C, though during wheat crop period it was 0.009 0C /year.