Document Type : Research Article
Tbriz University. Professor of Department of Planning and Environmental Sciences
University of Tabriz
Precipitation is the main component of the hydrological cycle, which is very important in many studies, including management of irrigation and drainage systems, crop performance, environmental studies, floods, droughts and etc. Therefore, in this study, 7 GCMs models of Coupled Model Intercomparison Project phase 6 (CMIP6) are evaluated in simulation and projection of precipitation changes in the northwest of Iran under three scenarios of SSP in three periods (2021-2050, 2051-2080, 2081-2100) compare to the historical period (2014-1985) was discussed. The trend of precipitation changes was calculated using Mann-Kendall test and Sen,s slope estimator. The Linear Scaling Bias Correction (LSBC) was used to downscaling the GCMs data and the validity of different models was evaluated using RMSE, MAE and R2 indices. Results of performance evaluation of CMIP6 models showed that among the studied models, MPI-ESM1-2-LR model with an average R2 equal to 0.86 and RMSE equal to 19.7 at the regional level were more accurate than other models in the simulation of precipitation. The results of projection also showed that precipitation according to SSP1-2.6 scenario will increase by 2.6% in the next three periods and on average in the end of 21st century and at most stations it is significant at the level of 0.01%. But according to SSP3-7.0 and SSP5-8.5 scenarios, the amount of precipitation will decrease by 14.5% and 3.6% in the end of 21st century, respectively, with the highest decrease being related to the rainy areas in the southwest of the region. In general, according to different scenarios, in most of the studied areas, the precipitation trend is decreasing until the end of 21st century, and it is necessary for officials and planners to adopt the necessary strategies to adapt to the resulting climate change.