Comparison of historical and future rainfall over Narmada River basin under changing climate

The present study compares the historical and future distribution, trends and rate of change in annual, seasonal and monthly rainfall over the Narmada River basin. The results have revealed an insignificant increasing trend in annual rainfall over the basin during the historical and future periods except its upper part, where decreasing trends have been detected. The rate of increase has been found slightly higher and significant in future rainfall, particularly under RCP8.5. At seasonal scale, the basin has experienced a negative trend in post-monsoon and winter rainfall during the historical period; but future rainfall estimates demonstrate increasing trends in all seasons except late century, where a non-significant decrease would be witnessed in winter rainfall under RCP8.5. The distribution of rainfall is likely to be consistent by the end of twenty-first century as coefficient of variation has been found less than 10%. Notably, the percentage area receiving below 700 mm of rainfall (lower rainfall) is expected to increase in monsoon months, reflecting an increased probability of dryness in future. These findings may assist the policy makers in making informed decisions related to agriculture, water resources management and preparations against the hydrological extremes in the upper, middle and lower parts of the basin.