Presentation of the suitable model for determining of fraction vegetation in arid area using of Satellite data IRS-LissIII Case Study: Sade Nahrein-Tabas

Estimation of vegetation features from space is a great challenge for agronomist، hydrologist and meteorologist communities. Now، the use of vegetation indices to estimate vegetation characteristics is very popular. They are empirical combinations between Visible (generally Red، R) and Near Infrared (NIR) reflectance that show good correlation with plant growth، vegetation cover، and biomass amount. The main objective of this study was to introduce a suitable model based on satellite images in order to estimate vegetation Fraction in Sade Nahrein basin (Tabas، Yazd، Iran). To do so، IRS-LISIII (2007)، ETM+ (2005) and vegetation fraction measured in fielwork (54 plots) have been used. Making comparable field data and pixel values، the average value of pixels located in the sampling sites was extracted and then 11 different vegetation indices were calculated. In the next step، the 6 output models have been evaluated using linear regression method and fitting the regression line between observations and estimated values in the validation data. The results showed that the model in which MSAVI1 was used has the highest accuracy (R2=0. 866) and therefore is the most suitable model for estimation of vegetation fraction in the study area.