Climatic change impact assessment on temperature, precipitation, and runoff of Droudzan catchment area of Fars province using multi-model ensemble mean approach.

This study investigated the effects of climatic changes on temperature, rainfall, and runoff in the Doroudzan catchment in the northeast of Fars province, Iran. Temperature and rainfall changes in two future middle and far period downscaled and studied using 15 CMIP3 climatic models, under emission scenarios A2, B1and A1B, from the database of the LARS WG5.5 model. The difference in the amount of variations in temperature and rainfall in the periods and the observational amounts under the 15 models indicated the uncertainty of the changes values. To reduce this uncertainty and limit the results to the management and planning of water resources, an ensemble approach was considered. For the preparation of the ensemble approach, the parameters from the files of the 15- models file scenarios were averaged so that a climatic ensemble model could be obtained for each period. Then, the runoffs of the next two periods were produced using the FEEDFORWARD neural network. The results indicated an increase in the average monthly maximum temperature and the minimum temperature. The results also showed a decrease in the rainfall in the early months of the year as well as an increase in the rainfall in the spring in most scenarios. Generally, results showed a reduction in the average annual rainfall. The maximum amount of reduction was in far future far period. Besides, a reduction occurred in the average runoff of the catchment in the periods, values in the most years.