Detection of Changes in Twentieth Century Precipitation in the Ganga River Basin

Abstract

Analysis of changes in 20th-century seasonal precipitation in the Ganga river basin is presented in this paper. High resolution gridded precipitation data were used for this purpose. A decrease in monsoon, as well as winter precipitation, was observed in the basin. No changes were observed in the pre- and post-monsoon seasons, however increasing trend in the precipitation was observed during the post-monsoon season, but these were found insignificant using the Mann-Kendal test at 10% significance level. Trend free pre-whitening (TFPW) method was used to remove the effect of significant lag1 autocorrelation from the data. The change points were estimated using Mann–Whitney–Pettit (MWP) method. It was observed that the year of change was earlier for locations where relatively higher decreasing trends were found. The change point in the winter season was found earlier than for the monsoon season. Overall it was observed that precipitation started decreasing significantly after the year 1960 in the basin.KeywordsGanga river basinPrecipitationTFPWMann–kendallClimate change