Sub-Basin Scale Characterizations of the Changes of the Future Rainfall Over the Ganges River Basin Using High Resolution Regional Climate Model

Global warming affects the seasonal rainfall variation and changes extreme rainfall events, in terms of frequency and intensity have an impact on the local, regional and global scales. An attempt has been made in this study to define the rainfall features of Ganges basin under moderate climate change scenario. The river basin has diversified climatic patterns. Ganges river basin is divided into 14 major sub basins. However, impact of climate change over Ganges is observed using Hadley Centers regional Climate model, PRECIS (Providing Regional Climates for Impact Studies). PRECIS simulation was carried out corresponding to SRES A1B scenario for a time period of 1971-2099. PRECIS generated rainfall shows deviation from observed rainfall therefore simulated rainfall needs to be corrected with respect to observed rainfall for impact studies. In these particular study PRECIS generated rainfall time series is bias corrected with respect to rainfall data of Indian Meteorological Department. The climate projections are examined over three time slices, viz. near (2020s, i. e.20112040), farther (2050s, i. e.20412070) and transient (2080s, i. e.20712099). Analysis indicates that monsoon rainfall increases 0.01 % at 2020s, 5.5 % at 2050s and 7.3 % at 2080s. Probability of rainfall extreme over Ganges basin such as maximum 1 day rainfall, count of consecutive rainfall days shows increasing trend, on the other hand number of rainfall event (greater than20 mm) on monsoon season shows decreasing trend.