Comparison the Drought Probability at Different Decade from Northwestern Area of Bangladesh

The study area is the northwestern region (24˚.30ˊ-26˚.40ˊN, 88˚.01ˊ-89˚.90ˊ E) part of Bangladesh is selected for drought analysis. We consider Rajshahi, Rangpur and Dinajpur district for the total time period 1980 to 2015. The daily rainfall data were converted into 5, 7 and 10 days rainfall data for different decade such as 1980-1989, 1990-1999, 2000-2009, 2010-2015. The choice of threshold value for Markov chain model is very important especially when it is used for agricultural purpose. The measurement unit of rainfall is millimeter (mm) with measurement instrument is standard rain gauge. After collecting the data for analysis we calculated them in decade-wise by using Microsoft Excel. After cleaning the daily rainfall data set we calculated them into different time interval like 5, 7 and 10 days by using Microsoft Excel then we use R program to analyze drought index under Markov Chain Model for threshold value 3 mm of rainfall. From empirical analysis we observed that the decades of different time scale in Rajshahi, Rangpur and Dinajpur are stable in different stages. Finally we conclude that Rajshahi and Rangpur districts were more drought prone than Dinajpur district. Among these three districts Rajshahi was the highest drought prone area and Dinajpur was the lowest drought prone area during the study period 1980 to 2015.