Climate change effect on Stream flow extremes in a river basin

Abstract

Climate change has main regional effects on temperature, evapo-transpiration, rainfall and ultimately stream flow. Climate change affects the amount and patterns of rainfall and is responsible for the changes in extreme hydrologic events like floods and low flow events. Flooding alone is one of the major natural disasters from an extreme storm event and is prevalent in many countries and majorly affects river morphology, modifying the flora and fauna of a given river environment. Vellar river basin is one of the semi-arid basins in Tamil Nadu, India which experiences extreme monsoon floods, intense rainfall in a short duration, irregular rainfall, severe drought in the non-monsoon seasons and very less groundwater recharge due to the presence of climate variability. The present study investigates the change if any in basin s climate through trend analysis and change point detection of temperature, rainfall and stream flow. The projection of future climate variables under climate change scenarios is done by using a statistical downscaling model (SDSM). The stream flow is simulated for the baseline and climate change scenarios through hydrological modelling by using a large scale hydrological model MIKE HYDRO Basin with MIKE 11 NAM rainfall-runoff model. The study also analyses the extreme high stream flow responses and magnitude with respect to different return periods under the baseline and future climate change scenarios. The trend analysis is carried out by a non-linear Mann-Kendall test. The test result shows that there is a significant increase in mean, maximum and minimum temperature trend. The maximum temperature change points are identified from the cumulative sum (CUSUM) chart in the years of 1985 and 2001. The minimum temperature change points are identified from the CUSUM chart in the years of 1987 and 2013 newline