Monitoring the Changes of Govater Estuary Mangroves Using Airborne-Space Imagery

Mangrove forests are a collection of trees and shrubs that are located in the tropics and this tidal plays an effective role in their growth, establishment and continuity of life. Mangrove ecosystems are found in tropical and subtropical regions of the world. Mangrove forests may exist in wide ranges between latitudes 35 ° N and 38 ° S. Mangroves are one of the most globally adaptable conservation ecosystems on the planet, providing invaluable services to coastal areas and the millions of people living in these communities, but because most of these services cannot be priced at market prices. As a result, the importance of these unique ecosystems is often underestimated. Due to the environmental role of mangrove forests, monitoring the changes in these forests is of particular importance. However, the location of these forests between water and land has made the direct study of this phenomenon difficult. In recent years, increasing attention to remote sensing science has removed barriers to access to these areas and made it possible to study these plants in any regional conditions. For this purpose, in this study, using telemetry data, the changes of Goiter estuary in the southeast of Sistan and Baluchestan province in a period of 30 years were investigated and Landsat satellite imagery (TM, ETM + and OLI sensors) from 1988, 1996, 2005, 2013 and 2018 were used. Developments were examined in the form of four study periods: 1988-1996, 1996-2005, 2005-2013 and 2013-2018. In order to calculate the amount of mangroves in this area each year and prepare a map of the distribution of mangrove masses, the Normalized Difference Vegetation Index was used. In the mentioned environmental conditions, only mangrove species are able to survive and the presence of other plant species in such conditions is far from the mind and as a result, this index can have a good performance in the field of mangrove studies. The study of mangrove values in the mentioned years showed a positive growth of mangrove values in the first three study periods. In the first period 32.31 hectares, in the second period 59.31 hectares and in the third period 1.17 hectares was added to the area of mangroves. This increase has more than doubled from 1988 to 2013. But from 2013 to 2018, there was a sudden decrease of 59.94. This reduction in area in tropical forests can be affected by various reasons. In this project, according to the comparison of the spectral diagrams of mangroves and the marginal waters of this cover, it seems that this reduction is false and is affected by the tidal phenomenon. The spectral behavior of two ranges proved that despite the differences between the two curves in reflection, their overall structure is the same and the red curve is a combination of water reflection and vegetation, indicating the presence of mangroves underwater when Is fashion. Therefore, it can be said that the decrease in 2018 was due to the placement of part of the mangroves under water and therefore there was no decrease in the area.