Spatial and Temporal Analysis of Rainfall Trend for 30 Districts of a Coastal State (odisha) of India

In the recent years the important scientific challenge faced by researchers worldwide is to have a better understanding about climate change at a regional scale. However, for all the regions the changes are unequal and have localized intensity. Therefore it should be quantified at a local scale. Precipitation is one of the important climatic variables responsible for climate change and required to be studied thoroughly. Odisha state is situated in east coast of India and agriculture plays a vital role in the state’s economy which is greatly dependent on rainfall. Any change in rainfall pattern due to climate change can adversely affect the agricultural production. Therefore in the current study, an attempt has been made to observe the spatial and temporal rainfall variability and trend over a period of 110 years (1901-2010) at regional scale for the state of Odisha. For examining the monotonic trend direction and magnitude of change over time, the statistical trend analysis techniques namely Mann-Kendall test and Sen’s slope estimator test were used. To determine the possible change points in the rainfall time series, Standard Normal Homogeneity test (SNHT) and Mann-Whitney-Pettitt (MWP) test were conducted. Inverse Distance Weighted (IDW) interpolation technique was applied in ArcGIS background for detection of spatial variation of rainfall on annual and seasonal basis in different districts of the state. The results of the analysis indicate that the annual rainfall was decreasing in northern region and extreme west region of Odisha with a maximum decrease (-1.425 mm/year) at Nuapada district, while highest decrease in monsoon rainfall (-1.25 mm/year) was found at district Sundargarh. In district Jagatsinghpur highest increase in rainfall was noticed in annual and monsoon season with maximum values 2.205 mm/year and 1.327 mm/year respectively, where significant change in annual rainfall was observed in the year 1961. Variation in rainfall was observed at different spatial scales of districts. This study gives district wise information on rainfall trend on long term basis and the impact of climate change in different parts of Odisha which will be helpful for a water resources manager in the planning and management of water resources for sustainable development.