Rainfall Insight in Bangladesh and India: Climate Change and Environmental Perspective

The analysis of detail characteristics of rainfall can be used to make a better decision for the availability of water, irrigation, agricultural water management as well as quality of life. Therefore, this study investigated details characteristics of rainfall in Bangladesh and India from 1951 to 2015. Rainfall features like Seasonality Index (SI) and Precipitation Concentration Index (PCI) were estimated to characterize spatial pattern of rainfall and Innovative Trend Analysis (ITA), Mann-Kendall (MK) and modified Mann-Kendall (mMK) test were used to detect trend in the data. Moreover, Sen’s slope (Q) estimator was used to calculate the magnitude of changes. Obtained rainfall seasonality index revealed that rainfall for the major portion of Bangladesh was markedly seasonal with a long dry season (SI= 0.80-0.99) with irregular distribution pattern (PCI = 16–20%). But in India, most of rainfall occurs in less than 3 months (SI = 1.00–1.19) with strong irregularity (PCI= >20%). Besides, most of the stations in Bangladesh showed increasing trends (60%) in annual rainfall, among them 33.33% were statistically significant (α = 0.05). However, India was dominated by significant decreasing trend (66.66%) for annual rainfall. For seasonal rainfall, pre-monsoon rainfall dominated by increasing trend (70%), on the other hand, both increasing and decreasing trend were found in monsoon, post-monsoon and winter rainfall in Bangladesh. Conversely, both positive and negative trend was observed in pre-monsoon, monsoon and post-monsoon rainfall in India with dominated decreasing trend (91%) in winter rainfall. The results of the ITA also showed more or less similar results which confirmed the reliability of this new method. The results of detail analysis of rainfall will be helpful for policymakers and scientist to focus on regional scale planning about water sharing, flood and drought situation between the country that will ultimately helpful for agricultural development and environmental planning.