Assessment the effect of drought and land use change on vegetation using Landsat data

Abstract

Drought is a disaster phenomenon especially in arid and semi-arid areas. Vegetation and its production play a main role in the social and economic issues in every country. In this study, Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) data have been used to monitor drought and the vegetation condition in Sonqor Abad in, Kermanshah province. Meteorological station data in the study area was used to study the SPI as a drought index. The maps of NDVI and also land use changes were provided using Landsat-TM images for 2001, 2008 and Landsat 8 images for 2015 in ENVI software environment. The obtained results showed that the land uses of cultivation and fallow have decreased and rangeland, urban and rock mass have increased. On the other hand, the dense of rainfall in the vegetation density has increased in this area during 2001 until 2015. Due to population growth and expansion of urban areas, the farm and garden lands have decreased around the city during this period. The correlation was found between vegetation density in mid-spring and the annual SPI of last year. Therefore, it can be concluded that there is a direct relationship between rainfall and the density of vegetation. By increasing the amount of rainfall and SPI, the vegetation density is increased. Based on the results, it is recommended that in addition to using meteorological data, satellite images should be used for monitoring the drought.