© 2020 1. Introducton Water resources of the planet Earth take part in the infnitely recurrent hydrological cycle, the largest movement of mater in the Earth’s system. Since water is the basic element of the life support system of the planet, it is of utmost importance to understand the impacts of the ongoing and projected climate change on water resources and water availability. Under balance of evidence, global warming is unequivocal and most of it is very likely due to the increase in atmospheric greenhouse gas concentratons. Observed climate change has extended beyond temperature. The likelihood of deleterious impacts, as well as the cost and difculty of adaptaton, would increase with the extent and the speed of global climate change. One of the efects of climate change is that hydrological extremes become more extreme. This leads to emergence of hot-spots and vulnerable areas, and the need for difcult adaptaton. Globally, the negatve impacts of climate change on freshwater systems are very likely to outweigh their benefts (Kundzewicz, 2008). Therefore, the study was planned with the objectves to prepare the various thematc maps, assess the diferent hydrological balance using SWAT modelling, analyze the probability of water balance Climate Change Impact on Hydrologic System in Aji River Basin Prasang H. Rank * , P. B. Vekariya and H. D. Rank College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh, Gujarat (362 001), India Article History RECEIVED on 14 th April 2020 RECEIVED in revised form 01 st June 2020 ACCEPTED in fnal form 03 rd June 2020 The CCAM (GFDL) RCM simulated daily maximum/minimum temperature and rainfall datafor 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 Distributon Mapping adoptng Gaussian and Gamma distributon respectvely. The warming trend of annual average of daily minimum and maximum temperature from 1970-2005 to 2006-2070 was found increased from 0.027 o C year -1 to 0.04 o C year -1 and 0.027 o C year -1 to 0.025 o C year - 1 respectvely. The rainfall, runof and groundwater recharge in the basin were found in statstcally stable trend in Aji basin. The best probability distributon was used for estmatng 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 respectvely 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 runof will be decreased in the future but the extreme event (100 year return period) of runof will be increased by the tune of 87.5%. The extremity (100 year return period) in the crop evapotranspiraton and ground water recharge may be decreased by -5.7% and -5.8% respectvely. Abstract Prasang H. Rank e-mail: prasangpatel83@gmail.com Aji basin, climate change, groundwater, hydrologic system, water resources Rank et al., 2020. Climate Change Impact on Hydrologic System in Aji River Basin. Research Biotica 2(2), 30-39. Corresponding Author Keywords How to cite this article? Open Access Artcle Id: RB0016 components and assess the climate change impacts on water resources of the basin. 2. Materials and Methods The CCAM (GFDL) RCM simulated daily maximum/minimum temperature and rainfall data(50kmx50km) for the base line period (1970-2005) and future scenario (2006-2070) for the IPCC SRES rcp 4.5 for 4 grid point falling in Aji basin were taken from the IITM, Pune. Conformal-Cubic Atmospheric Model (CCAM) RCM is a recent earth-system model developed by a Consortum of Common Wealth Scientfc and Industrial Research Organizaton (CSIRO), (McGregor and Dex, 2001) run under the experiment named as CCAM (GFDL), based on state-of-the-art models for the atmosphere, the ocean, sea ice and the biosphere. In partcular, the model is based on the concept of “seamless predictons”: numerical weather predicton (NWP) models are sophistcated state-of-the art models which, being based on the same physical principles, may provide advanced atmospheric components for climate models. The CCAM RCM data were driven by the GFDL-CM3 GCM. The software namely (a) Remote sensing and GIS sofware –Arc GIS V10.1, (b) Remote sensing and GIS sofware Research Biotica 2020, 2(2):30-39 30 Research Article Journal Home: www.biospub.com/index.php/resbio DOI: 10.54083/ResBio.2.2.2020.30-39