1National Institute of Hydrology, Roorkee 247667 (Uttarakhand), India. vijay@nih.ernet.in
2Department of Water Resources Development and Management Indian Institute of Technology, Roorkee 247667 (Uttarakhand), India. jainsfwt@iitr.ernet.in
This study aims to determine trends in the annual and seasonal total rainfall over Ganga-Brahmaputra-Meghna river basins of India. The data used in this study consists of daily gridded rainfall data at 1º×1º resolution for the period 1951–2004. The basin wise data series was created as the averaged data over all the grid points falling in that particular basin. Sen's non-parametric estimator of slope was used to estimate the magnitude of trend. The statistical significance of a trend was assessed by the Mann-Kendall test. Brahmaputra river basin showed a decreasing trend, Meghna river basin showed an increasing trend and Ganga river basin showed no change in annual rainfall during the period 1951–2004. Monsoon rainfall was found to have increased over Brahmaputra and Meghna and decreased over Ganga basin. Rainfall increased over Ganga and Meghna basins in pre-monsoon season and over Meghna basin in post-monsoon season. The winter rainfall was found to have increased over all the three river basins. None of the increasing or decreasing trend is found significant at 95% confidence level.
Rainfall, Trend, Ganga-Brahmaputra-Meghna, Non-parametric, Mann-Kendall test
