Using Lancaster Index to Analyse of the Sand Dunes Activity in Arid lands and Sensitivity Analysis of the Factors Affecting it (Case Study: Buin-Zahra City)

Wind erosion and sand dunes mobility has adverse environmental consequences. Identification of factors affecting sand dunes mobility and predicting their future status is essential to control the desertification process. Therefore, in the present study, the mobility of flowing sands in the southeast of Qazvin province has been studied and analyzed. For this purpose, hourly wind speed data, dust phenomenon code, rainfall and temperature of Buin Zahra station were used for the statistical period of 2006-2006. Rainfall and temperature data were used to calculate the rate of evapotranspiration Thornthwaite method. After calculating the percentage of erosive winds and aridity index, by using Lancaster index, the mobility of flowing sand in the southeast of Qazvin province was investigated and analyzed. Sensitivity analysis test was used to predict the effect of climate change on mobility of sand dunes. Results showed that sand dunes mobility was inactive in previous years and activated in recent years. Examining the relationship between the number of dusty days and the Lancaster index using two-variable linear regression showed that there was no strong and significant relationship in the study period between these two parameters, while a significant relationship between Lancaster index and aridity index. These results indicate that 42% of the changes in the Lancaster index were due to changes of the aridity index. The results of the sensitivity analysis showed that if the average of the wind speed and evapotranspiration rate increased by 30% in future, or amount of precipitation decreased by 30%, the status of the sand dunes mobility would change from inactive to active and crossing this threshold could be the reforming of wind erosion activities in the area.