Methods and Assumptions GLACINDIA 09-10 April,2015 Jawaharlal Nehru University, New Delhi Separating the impacts of Climate Change and Human Activities on mean annual streamflow using SWAT Pankaj Dey1 and Ashok Mishra2 1 M.Tech student (pdey609@gmail.com) , 2 Associate Professor (amishra@agfe.iitkgp.ernet.in ) Land and Water Resources Engineering, Agricultural and Food Engineering Department Indian Institute of Technology Kharagpur, Kharagpur- 721302, West Bengal Introduction Climate change and human activities have altered the hydrologic cycle and have exerted global-scale impacts on our environment. Human activities have changed the temporal and spatial distribution of natural water resources. Water resource planning and management increasingly need to incorporate these two impacts in order to future water supplies. This study is necessary for framing and implementation of adaptation and mitigation strategies. Calibration period (1953-1964);NSE=0.69,R2 = 0.68; (b)Validation period (1965-1974); NSE=0.59;R2 = 0.56 (a) (b) Purpose To analyze the trend of mean annual rainfall and mean annual streamflow. To determine the change point in the natural streamflow regime. To separate out the individual impacts of climate change and human activities on streamflow variability using SWAT model. Methods and Assumptions Mann Kendall Trend test was performed to analyse the trend of mean annual rainfall and mean annual streamflow (Patra et al., 2012) Sequential Mann Kendall test was used for detection of change point in the natural flow regime of streamflow (Zhang et al., 2008). The period before change point considered to be natural period and after, it was considered as both natural and human impacted period (Wang et al., 2013). The Soil Water Assessment Tool (SWAT) was used to calibration and validation for the natural period to simulate the natural flow conditions during impacted period (Wang et al., 2013). Natural streamflow simulation during the impacted period. Conclusions Mean annual rainfall shows a increasing trend at the rate of 0.17 mm/year. Mean annual streamflow shows a decreasing trend at the rate 1.652 m3/year. The year 1974 is the change point of the natural streamflow regime. From SWAT simulation, it is found that 51.37% of decrease in streamflow is due to climate change. Human activities exhibit 48.63% of decrease in streamflow. Climate change is the dominant factor for water resources availability but both the drivers should be considered for development of adaptation strategies. Results Mann Kendall trend test of mean annual streamflow and mean annual precipitation from 1950-2005. Streamflow is showing decreasing trend whereas rainfall is showing increasing trend in he region. References: Patra, J. P., Mishra, A., Singh, R., and Raghuwanshi, N. S. (2012). Detecting rainfall trends in twentieth century (1871–2006) over Orissa State, India.Climatic change, 111(3-4), 801-817. Wang, W., Shao, Q., Yang, T., Peng, S., Xing, W., Sun, F. and Luo, Y. (2013), Quantitative assessment of the impact of climate variability and human activities on runoff changes: a case study in four catchments of the Haihe River basin, China. Hydrol. Process., 27: 1158–1174. doi: 10.1002/hyp.9299 Zhang, X., L. Zhang, J. Zhao, P. Rustomji, and P. Hairsine (2008), Responses of streamflow to changes in climate and land use/cover in the Loess Plateau,China,WaterResour. Res., 44, W00A07, doi:10.1029/2007WR006711. Sequential Mann Kendall test of mean annual streamflow for change point detection. The year 1974 is the change point of the natural flow regime of the river