Vol. 19 No. 1
Rainfall probability and trend analysis for strategic crop planning with their impact on the existing cropping system in the new alluvial plains of West Bengal
Author(s): T. MANNA
Abstract: Daily rainfall data for the period of 36 years (1985-2020) of new alluvial zone of West Bengal has been analysed to understand weekly, monthly, seasonal and annual distribution pattern along with expected rainfall amount at 90%, 75% and 50% probability levels. The Mann-Kendall test for monotonic trend analysis together with the nonparametric Sen’s slope estimator was applied to estimate the magnitude of the seasonal rainfall trend. The results revealed a long term declining trend of winter and post monsoon rainfall, whereas increasing trend was observed in summer and south west monsoon rainfall. Annual rainfall of the region ranged from 1523.4-1786.4 mm out of which 198.4-264.6 mm was received in summer/pre-kharif, 1138.5-1334.4 mm during monsoon/ kharif, 157.4-185.7 mm during post monsoon and 29.1-34.6 mm during the winter season. Weekly rainfall during the monsoon (23rd -39th SMW) at 90% probability ranged from 7.9-36.5 mm, 18.9-55.5 mm at 75% probability and 37.6- 84.1 mm at 50% probability level. The ideal combination of crops for this regions may be kharif rice in medium and lowland, vegetables, ground nut etc. in the upland in the kharif; mustard field pea, potato in upland during the rabi season.
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