Spatial and Temporal Trends of Monthly, Seasonal and Annual Precipitation in Districts of Jharkhand in India

Abstract

Characterization of spatial variability and temporal trends in precipitation in a changing climate is vital to assess climate-induced changes to support adequate agricultural planning and water resources management strategies for the future. In this context, spatial and temporal variability in the precipitation over Jharkhand state in Eastern plateau and hill region is investigated. Spatial distribution of precipitation was mapped using ‘ordinary kriging’ geostatistical interpolation technique. A comprehensive precipitation trend and periodic analysis at the monthly and seasonal scale on a 40 year data series (1975-2014) for 18 locations in Jharkhand are presented using Mann-Kendall and Sen’s slope methods. The seasonal and annual precipitation showed large spatial variability across the Jharkhand. Although, the spatial distribution of monsoon and annual precipitation are roughly similar, annual precipitation varied considerably in space due to the variations induced by pre-monsoon and winter precipitation. The statistical analysis revealed predominantly decreasing trends, both at the annual and seasonal scale. July precipitation showed significantly decreasing trend (-3.17 to -6.21 mm/year) in large number of districts (15), while the trend in May and other ‘monsoon’ months was not significant. Over the reference period, the negative trends in monsoon, winter and annual precipitation were significant for 61, 67 and 50% of the total districts analyzed with rate of decrease for monsoon and annual precipitation in the range of -5.3 to -13.0 and -5.3 to -15.9 mm/year, respectively. In view of the rainfall dependence of the agriculture in the state and decreasing trends of precipitation, the information presented in this paper can supports further climate change risk assessment and vulnerability adaptation planning.