A Comparative Study of Applying the Hadcm3 and ECHO-G Softwares to the Climate Change Assessment of the Babolroud Watershed Between 2046-2065 Period

The Babolroud watershed has experienced different climate related events such as flooding and drought in recent years that emphasize the urgent need to investigate the impact of climate change on meteorology and hydrology of the watershed. Two general atmospheric circulation softwares were used to predict these changes. However, the large scale computational grid of such software discourages their application to meteorology parameters prediction in small scales. Therefore, an interface tool called the LARS- WG model has been developed to facilitate assessment of such parameters in more manageable scales and at the desired localities. The data generated by the HadCM3 general circulation of the atmosphere software were incorporated into the LARS-WG software under a similar scenario for the 2046-2065 periods. They were downscaled, compared and evaluated the four climatic variables related to the statistical base period of 1982-2011. These data were introduced into the LARS-WG software for calibration and verification. Furthermore, the relationships between the collected data were established between rainfall depth, maximum and minimum temperatures and radiation to simulate the future events. It was observed that the ECHO-G software prediction was lower for precipitation and higher for temperature under the similar scenario as compared to those predicted by the HadCM3 software. Precipitation depth as predicted by this software for the Babolroud watershed ranged from -52 to %. The results indicated a moderate increase in precipitation in the rainy season and an extreme decrease in the summer month. The highest reduction was related to the August rainfall (43 mm) as predicted by the ECHO-G software. The highest increase in precipitation was related to October (27 mm) as predicted by the HadCM3 software.