Vol. 7, Issue 10 (2018)

Author(s):
S Pattanayak, BS Rath, S Pasupalak, A Baliarsingh, AKB Mohapatra, A Nanda and GS Panigrahi

Abstract:
Seasonal variability of rainfall in different blocks of Khordha district is of utmost importance in this existing scenario of changing climate and temperature. The present study has been undertaken using rainfall data of the district for 25 years (1993-2017). Seasonal rainfall has been characterised under four seasons-Winter, Summer, South west monsoon and north east monsoon which contributes around 1.5%, 10.5%, 72.7% and 15.3% respectively to the mean annual rainfall of the district. Year wise variability of rainfall revealed that year 2013 has received the maximum annual rainfall (1873 mm) in 105 rainy days and year 1996 has received least annual rainfall (778 mm) in 80 numbers of rainy days. Trend line analysis of annual and seasonal rainfall and rainy days visualised a decreasing trend in number of rainy days whereas as slightly decreasing trend in annual rainfall and slightly increasing trend in seasonal rainfall. Extreme rainfall events of different blocks were different depending upon the highest amount of rainfall they received in the last 25 years. Markov Chain probability model determined the initial and conditional probabilities of dry and wet weeks at 20 mm threshold limit. Initial land preparations can be done in the standard meteorological weeks having more than 30% of initial probability of wet weeks (21-23 SMW) and sowing or transplanting can be done in the SMWs having more than 50% of initial probability of wet weeks (24-26 SMW). PET is also an important factor in assessing the drought condition and for better crop water management planning. PET calculated by modified Penman method is of more concern and it has been found out from the graph that the post monsoon period (October to December) and pre monsoon period (January to May) is having water deficit condition whereas monsoon period (June to September) is having water surplus condition. The surplus water needs to be stored for efficient utilisation in the future.