ORIGINAL PAPER A strategy to assess the uncertainty of a climate change impact on extreme hydrological events in the semi-arid Dehbar catchment in Iran Ahmad Sharafati 1 & Elnaz Pezeshki 2 Received: 19 March 2019 /Accepted: 15 August 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019 Abstract This study presents a robust approach to assess climate change impact variability on future extreme events (e.g., rainfall depth and river discharge) over Dehbar catchment in Iran. Climate change impact is assessed using five general circulation models (GCMs) including EC-EARTH, GFDL-CM3, HadGEM2-ES, MIROC5, and MPI-ESM-MR with several emission scenarios (e.g., RCP26, RCP45, and RCP85). Daily discharge data is simulated based on the distributed rainfall-runoff model called Soil and Water Assessment Tool (SWAT), while calibration and validation phases are performed using SWAT-CUP. Future annual extreme events (i.e., rainfall depth and river discharge) are computed by means of frequency analysis. Results show that future annual maximum values are increased significantly, where the most increase occurs in the future annual river discharge and rainfall depth according to the EC-EARTH-RCP85 as 142% and 81% with MPI-ESM-MR-RCP85 model. The highest future extreme river discharge and rainfall depth values through different return periods (50–1000 year) are obtained from EC-EARTH-RCP85 as 6.8~8.08 cms and 57.41~105.76 mm based on EC-EARTH-RCP45 model. Uncertainty analysis results indicate that climate models/scenarios have significant effect on the future extreme events variability, while the same for extreme river discharge is the least sensitive to different return periods. Keywords Uncertainty . Climate change . River discharge . Rainfall depth . Extreme events 1 Introduction Global warming and climate change have major impacts as a result of greenhouse gas accumulation in the atmosphere. Several hydrological variables such as surface runoff, evapo- transpiration, and infiltration are affected by climate change (Nilawar and Waikar 2019). Intergovernmental Panel on Climate Change (IPCC) reports indicate towards temperature and precipitation increases leading to extreme floods and droughts (Masson-Delmotte et al. 2018). Furthermore, climate change has an undeniable role in flash floods and droughts across the world (Chhogyel and Kumar 2018; Nabaei et al. 2019; Qutbudin et al. 2019; Sayl et al. 2016; Xiao et al. 2018). It has also significant effects on climate variable uncer- tainty, especially concerning precipitation spatial and inter- annual variations (Pauling et al. 2006; Sharafati and Zahabiyoun 2014, 2013). In this regard, several studies have been conducted to assess the effect of both convective and stratiform precipitation scenarios on hydrological cycle (American Society of Photogrammetry and American Society for Photogrammetry and Remote Sensing, 2000; Lenderink et al. 2011; Ren et al. 2018; Roxburgh et al. 2019; Yuan et al. 2017). Along this line, several climate models have been de- veloped based on the dynamic and thermodynamic changes in atmosphere to address the climate change impacts (Khazaei et al. 2012; Rulfová et al. 2017; Zahabiyoun et al. 2013). There are many general circulation models (GCMs) that have been developed to assess the climate change impacts on the hydrological events (Sánchez et al. 2004; Stevens et al. 2013). Several studies are performed to assess the quality of GCMs in precipitation characteristic prediction (Kephe et al. 2016; Nigussie and Altunkaynak 2019; Ren et al. 2019; Verma et al. 2019). Resolution and parameterization * Ahmad Sharafati asharafati@srbiau.ac.ir 1 Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran, Iran Theoretical and Applied Climatology https://doi.org/10.1007/s00704-019-02979-6