Investigation of Rainfall Trend in Jorhat Town, Assam Mayurakshi Bhuyan Baruah Department of Geography, North-Eastern Hill University Shillong , Meghalaya, INDIA id: (M)

Generalities Rainfall is the Prime Source Jorhat experiences South-west Tropical Monsoon Importance of rainfall Analysis

Study Area

Data Base and Methodology Secondary data of Rainfall ( ) Tocklai Experimental Station, Jorhat Mean Moving Average Least Square Method Co-efficient of Variation

Results and Discussion Mean Annual Rainfall Decadal Rainfall Variability Seasonal Variability of Rainfall

Mean Annual Rainfall cm per annum cm in summer monsoon cm in winter season

Mean Monthly Rainfall 1.91 cm (January) cm (May) cm in August, 1963 (Highest) -37 per cent of the total rainfall

Annual Rainfall cm (1977)-Highest cm (2001)-Lowest 82 per cent of total annual rainfall-May to October 18 per cent of total annual rainfall-December to April

Trend of Annual Rainfall Fig. 1: Trend of Annual Rainfall (cm) in Jorhat Town

Trend of Annual Rainfall Fig. 2: Trend of Annual Rainfall in Jorhat Town ( )

Decadal Rainfall Variability DecadesTotalAverage Standard Deviation Coefficient of Variation Table 1: Decadal Rainfall Variability (cm) in Jorhat Town ( ) (Source: Rainfall in Jorhat ) Fig. 3: Decadal Rainfall Variability (cm) in Jorhat Town

Seasonal Variability of Rainfall Seasons MonthsTotalAverage Maxi- mumMini-mum Standard Deviation Coefficient of Variation WinterJan Feb Pre- monsoon Mar Apr May MonsoonJun Jul Aug Sep Post- monsoon Oct Nov Dec Total Table 2: Seasonal Variability of Rainfall (cm)in Jorhat Town ( ) (Source: Rainfall in Jorhat ) Fig. 4: Seasonal Variability of Rainfall (cm) ( )in Jorhat Town

Conclusion Decreasing trend of rainfall Post-monsoon Season has suffered Highest decadal rainfall variability ( )

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