The Impact of Future Climate Change and Human Activities on Hydro-climatological Drought, Analysis and Projections: Using CMIP5 Climate Model Simulations

Abstract

Both climate change and human activity are the important drivers that can change hydrological cycle routs and affect the features of hydrological drought in river basins. The current study selects the Zayandeh Rud river Basin as a case study region in which to evaluate the influences of climate alteration and human activity on meteorological and hydrological drought based on the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) on different time scales. The generated local climatic data of future years (2006–2040), (2041–2075) and (2076–2100) under the severest scenario (RCP 8.5) from the CMIP5 climate model are selected and used for the hydrology model and water allocation model of WEAP to construct hydrological drought which also consider human activities. The results indicate that significant meteorological drought is expected to occur in the winter and spring months of January to June. However, the driest month for hydrological drought is in the summer and autumn (July to December) (e.g. no changes in seasonality of droughts compared to historic period). It is concluded that, in the results of this work, the human influences on projected hydrological drought have been outlined; they had been missed in many projections for future hydrological drought. However, this study confirms the previous study (Bierkens et al. 2012) which mentioned that human influences can account for future hydrological drought in areas of Asia, the Middle East and the Mediterranean. The results attained in this study are beneficial for examining how hydrological drought characterizations respond to climate alteration and human activity on several time scales, thereby providing scientific information for drought predicting and water resources management over various time scales under non-stationary circumstances.