Evaluation of climate change on temperature and precipitation trends in Barandozchay watershed, In the West Azerbaijan, using General Circulation Models (GCM)

Climate change is a natural phenomenon that occurs in sequences of long-term return periods. Human activities impacts cause to aggravate the effects of sequences of climate changes, the intensity of changes trend and intervals. Climate change can be studied by the meteorological parameters as its indicators. The purpose of this study is to simulate the consequences of global climate change on temperature and precipitation in Barandoezchay watershed. First, the watershed climatic data from 1990-2009 were collected on daily basis, and LARS-WG model was applied to downscale data obtained from GCM models That were selected and daily climatic data was generated until 2040.Then, the trends of temperature and precipitation for the study watershed were analyzed. The results showed that in future period’s temperature component will increase compared to the base period. So that under two GCM models that used in this study and 5 scenarios of greenhouse gas emissions, this increase is seen. Also the results showed that rainfall rate will increase significantly in the future. But however, there are changes in temporal patterns of precipitation. Annual average of rainfall in the base period is 287.37 mm, and this rate for A1B and A2 scenarios in the CNRMCM3 model are 324.55 and 356.28 mm respectively. This rate for A1B, B1 and A2 scenarios in the IPSLCM4 model are 320.44, 333.6 and 324.63 mm respectively, that highest increase is in the A2 scenario in CNRMCM3 model. Although there is the decrease in rainfall in some scenarios of this models. However there are rainfall increases in the most of studied scenarios of all models, but temperature increase can counteract rainfall increasing with the increasing in the evapotranspiration and increasing in plants water demand. On the other hand, Due to the rainfall will decrease in the winter, the snow that fallen in region and is the main source of ground water storage, will be reduced.