Simulation and prediction some of climate variable by using multi line SDSM and Global Circulation Models (Case study: Bar Watershed Nayshabour)

One of the weaknesses of GCMs model are large spatial scale in simulated of climatic variables that for hydrological studies and water resources in the range of watershed area are not sufficiently accurate. So should by using the different techniques that downscale. Then downscaled outputs are used for assessing the impact of climate change on hydrological studies. Among downscaling approaches, statistical methods are of great importance among hydrologists due to their easy and quick performance. In this study, statistical model (SDSM) was evaluated for simulating and predicting minimum and maximum temperature, precipitations in the bar Nayshabur watershed. For executing SDSM model outputs of CGCM1 and Hadcm3 models were applied. Daily data of minimum and maximum temperatures precipitations for the basic period (1970-2000) were simulated under three A1, A2 and B1 scenarios. Based on Statistical parameters, outputs of Hadcm3 model under A2 more compatible with the basic period. Obtained results showed that during 2010-2039, 2040-2069and 2070-2099, the average temperature 0.01, 0.3 and 0.6, the average minimum temperature 0.3, 0.5 and1. 4 and the average maximum temperature 0.7, 1.4 and 2.7 ° C will increase compared to the basic period in the studied basin. Also, the results showed that within three studied periods, the average rainfall will decrease 6, 10 and 17 mm respectivity comparing to the basic period.