Climate Change Impact on Hydrologic System in Aji River Basin

Abstract

The CCAM  (GFDL) RCM simulated daily maximum/minimum  temperature and rainfall data for the base line period (1970-2005) and future scenario (2006-2070) for the IPCC SRES rcp 4.5 for 4 grid points (50kmx50km) falling in Aji basin were bias  corrected using Probability Distribution Mapping adopting Gaussian and Gamma distribution respectively. The warming trend of annual average of daily minimum and maximum temperature from 1970-2005 to 2006-2070 was found increased from 0.027°C year^-1  to 0.04°C year^-1  and 0.027°C year^-1  to 0.025°C year^-1  respectively. The rainfall, runoff and groundwater recharge in the basin were found in statistically stable trend in Aji basin. The best probability distribution was used for estimating each water balance component. The crop water requirements during winter,  summer and monsoon  season may  increase/decrease by  the tune of 6.4%,  -0.3% and 1.5% during winter,  summer and monsoon  season respectively in the future as compared to the past, due to climate change impacts. The monsoon seasonal rainfall will be decreased in the future due to climate change impacts. However, the extreme rainfall (100 year return period) event will be increased in the future by the tune of 39%. Similarly, the runoff will be decreased in the future but the extreme event (100 year return period) of runoff will be increased by the tune of 87.5%. The extremity (100 year return period) in the crop evapotranspiration and ground water recharge may be decreased by -5.7% and -5.8% respectively.