Monitoring and determination of the urban green coverage threshold based on Landsat data, Case study: Zones 1 and 6 from Shiraz city

Changing the use of urban green cover over time can create various environmental hazards for the citizens of a city. Due to the importance of the subject, the present study intends to investigate the temporal and spatial changes of green cover in areas 1 and 6 of Shiraz metropolis using Landsat satellite images during five decades (1972 to 2019). For this purpose, after performing radiometric and atmospheric corrections, maps resulting from plant indices including NDVI, SAVI, OSAVI as well as the maximum likelihood algorithm were prepared in ENVI5 software and classified and evaluated in Spatial Information System (GIS). The results of this study showed that the area of the green cover in region 1 has decreased in terms of hectares in NDVI, SAVI, OSAVI indices respectively and also in the maximum likelihood algorithm has decreased from 1394 to 428, from 789 to 421, from 815 to 419, from 1402 to 439, respectively and in region 6 was decreased from 1374 to 858 (NDVI), from 1160 to 862 (SAVI), from 1149 to 884 hectares (OSAVI) and in the algorithm, the maximum likelihood of similarity has decreased from 1393 to 855 hectares. Investigation of threshold values of plant indices to identify urban green cover showed that the range of threshold values in NDVI was variable from 0.2 to 0.3, in SAVI was variable from 0.44 to 0.47 and in OSAVI was variable from 0.34 to 0.36 and using Pearson test in SPSS software, correlation coefficient values between NDVI, SAVI, OSAVI, maximum likelihood algorithm and the studied years were significant at the 1% level. The results of this test also indicated that there was no significant difference between the results of these methods in this study. This reduction of green cover is considered a serious danger for the citizens of Shiraz