Rainfall probability analysis for crop planning in Kandhamal district of Orissa, India

Kandhamal district lies between 83.30° E to 84.48° E longitude and 19.34° N to 20.54°N latitude. The district headquarter is Phulbani located in the central part of the district. Phulbani is situated at 20° 28′ N latitude and 48.13′59” E The average rainfall at Kandhamal is around 1500 mm, though it receives high amount rainfall but most of the rainfall (84%) occurred during kharif. So most of the crops get low yield due to improper crop planning. Thus, the study was undertaken to carry out probability analysis of annual, seasonal, monthly and pentad rainfall data of Kandhamal district. Rainfall data were collected from Collectorate office Kandhamal from 1968 to 2009(42 years). Pentad, monthly, seasonal and annual rainfall were analysed. Probability analysis were made and equations were fitted to different distributions and best fitted equations were tested and chi-square test was made. It is observed that rainfall during June to September is more than 100 mm and cropping pattern like paddy(110 days) mustard is suitable to the region. Also, if the kharif rain can be harvested and reused for another rabi crop by using sprinkler or drip irrigation, it will give benefit to the farmers. The pentad analysis shows that the pentads which received less than 12.5 mm may be looked into at 75% probability level and different steps may be made to irrigate during that period from pond or irrigation. The field should be ploughed before 33 ^rd pentad and should be kept ready for sowing. Sowing can be done in the 34 ^th pentad. From 43^rd to 50^th pentad, the rainfall is almost constant. The availability of rain water for crop is assured at 75% probability levels. Excess runoff should be collected in some storage structures so as to use it for irrigating post-monsoon crops.