Environment Assessment
Maryam Dahmardeh Pahlavan; Mohsen Shahriari Moghadam; Saeedeh Maleki Najafabadi; Vahid Rahdari
Abstract
Introduction: Coastal areas worldwide hold significant social and economic importance. These areas, in addition to providing essential ecosystem services, have considerable potential for activities such as tourism, industry, and transportation, contributing significantly to the economic and social development ...
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Introduction: Coastal areas worldwide hold significant social and economic importance. These areas, in addition to providing essential ecosystem services, have considerable potential for activities such as tourism, industry, and transportation, contributing significantly to the economic and social development of countries. Given that coastal areas are among the most complex ecosystems, they require monitoring and planning for enhanced protection. Timely and accurate identification of land use changes, which form the basis for better understanding human-nature interactions, provides the necessary groundwork for the efficient management and utilization of coastal resources.Materials and Methods: The present study aims to investigate land use and land cover changes in the Chabahar coastal areas for four periods, including the years 1368, 1378, 1388, and 1398, using Landsat satellite time series data. Land cover mapping was performed through preprocessing and processing stages, followed by classification using a combined method. The accuracy of the produced maps was assessed using error matrix, Kappa index, and overall accuracy, which were greater than 80% and 0.8, respectively. Land use changes were analyzed using landscape metrics.Results: The results indicated that barren land had the highest land use percentage in all studied years. Saline and barren land cover decreased by 398.28 and 75.7 hectares, respectively, from 1368 to 1398, while aquatic land cover increased by 115.3 hectares in 1398 compared to 1368. The analysis of vegetation cover also revealed that this land use, along with human-made structures, consistently allocated the smallest area in all periods, gradually increasing. The accuracy assessment of land cover classification showed high accuracy in the produced maps, with the highest and lowest accuracy rates in 1368 (93.25%) and 1398 (85.6%), respectively. In 1398, the number of patches for aquatic land, vegetation cover, and human-made structures increased (830, 2662, and 4, respectively) compared to 1368 (146, 2386, and 1, respectively), while the number of saline and barren land patches decreased in 1398 (643 and 761, respectively) compared to 1368 (720 and 1060, respectively).Discussion: The study results demonstrated considerable changes in the Chabahar coastline over the past 30 years. The findings indicated a significant increase in vegetation cover from 1368 to 1398 (from 116.34 to 202.30 hectares), contributing a total of 85.96 hectares to land use. This increase in vegetation cover can be attributed to agricultural expansion. The detection results of changes in human-made areas also showed substantial growth (133.18, 205.74, 228.29, and 411.42 in 1368, 1378, 1388, and 1398, respectively) during the study period. Overall, it can be concluded that, based on the analysis of landscape metrics, the increase in human-made land uses and environmental changes has continued, and integrated management plans for coastal areas have not been adopted.
Fatemeh Izadi; Atefeh Chamani; Rasool Zamani Ahmadmahmoodi
Abstract
One of the most important invasive plant species in Iran is the American mesquite tree (Prosopis juliflora) which has taken the control of a large area of south and southeast Iran. The invasive effect of this species is profound such that it is the dominant species in some areas and the only tree ...
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One of the most important invasive plant species in Iran is the American mesquite tree (Prosopis juliflora) which has taken the control of a large area of south and southeast Iran. The invasive effect of this species is profound such that it is the dominant species in some areas and the only tree species in most coastal ecosystems of southern Iran. Regardless of draining underground water as the only source of drinking water for local communities and destroying livestock feed, simplifying the ecosystem to only one tree species is a serious alarm of losing the ecosystem balance and causing serious economic and social effects. Considering the importance of the management of American mesquite trees in the south of Iran, this research investigated the spread of American mesquite trees using satellite image processing.Materials and Methods: Among the 45 identified species of the genus Proposis, few of them, especially the American mesquite, are known as invasive species. This plant is known as the most threatening invasive plant in Europe. In the red list of the International Union for Environmental Protection, American mesquite is mentioned as one of the world’s 100 invasive species threatening. In this study, an area of 1850 km2 between the two cities of Sirik and old Jask was investigated. Pixel-based processing of Landsat 8 satellite images (OLI sensor) was used to extract the tree cover map of the area. The land units (areas covered with similar soil and vegetation characteristics) were produced using the object-oriented processing of Landsat 8 satellite images. Finally, the dominance of American mesquite compared to other trees was calculated in each unit and their canopy density changes were investigated and analyzed using the MODIS vegetation index in a 20-year period. Results: According to the results, 13417 ha of the study area is covered by various trees. The American mesquite tree class was the second largest tree class (3991 ha, 29% of the total tree cover) with a heterogeneous distribution and is often located in areas with light and salty soils along the streams. Areas with a strong predominance of mesquite (more than 60%) accounted for 11% of the area which was mostly located in the central parts of the region. Discussion:The results of the image classification showed that the American mesquite heavily occupied areas are mostly located along the main rivers and channels, extending from the eastern highlands towards the waters of the Strait of Hormuz. Thus, proximity to rivers and waterways can be considered as one of the most important environmental factors affecting the spread of these trees. In areas with a strong dominance of American mesquite trees, it was expected that the plant biomass will increase significantly as observed by their high NDVI values. However, the noteworthy point is the increasing rate of the average values of the NDVI index during the last 20 years in the most dominant units, which is now increasing at a high rate with an average NDVI exceeding 0.5 since 2017. This indicates the increasing spread of the American mesquite in the region and even in the areas that have hosted this invasive species for decades.
mohammad hossein bagheri; mohammadReza Farzaneh; behzad rayegani
Abstract
AbstractIntroduction: Flood is one of the main natural disasters in Iran, which has caused losses in different regions. The ability to produce accurate and timely flood assessments is an important safety tool for flood mitigation and response. Several methodologies have been developed to indicate the ...
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AbstractIntroduction: Flood is one of the main natural disasters in Iran, which has caused losses in different regions. The ability to produce accurate and timely flood assessments is an important safety tool for flood mitigation and response. Several methodologies have been developed to indicate the risks associated with flooding by using ground measurements. Satellite remote sensing data have been used for flood assessment because of their spatial resolution and capacity to provide information for areas of poor accessibility or lacking in ground measurements. High resolution satellite data is mainly useful for the spatial analysis of water pixels. When flood data (before and after of a flood event) are available, it is possible to classify land cover change, and thus identify which areas are flooded.Materials and Methods: The present study developed a methodology that uses Sentinel 1 images and global products to assess the losses caused by a flood in the province of Khuzestan (2020) and Chabahar-Konarak (2021-2022). In this study, in addition to Sentinel 1 satellite data, Landsat 8 satellite images have been used. The results of this research have turned into the development of a flood application in the Google Earth Engine software.Results: The results showed that the use of optically inactive images of this Landsat 8 or Sentinel 2 in cases where the cloud cover does not bother will increase the accuracy of the output. This issue is one of the specialization features in the conditions of uncertainty in determining the thresholds of changes in radar images. In the field of flood zone and subsequently estimation of losses from flood. Applying the method presented in the Google Earth Engine environment, due to the easy access to satellite images and global products, is a suitable solution for extracting the flood zone and subsequently estimating the agricultural and residential damages caused by floods.Discussion: Combining the information of radar and optical satellites can play an important role in the accuracy of the thresholds and extracting the flood zone. The limitations related to optical images such as cloud cover disturbances led to the use and evaluation of methodology based on radar images (without the use of optical images) in this research. According to the research methodology, there is no need to prepare and collect land information and global products regarding the population and its spatial distribution, land cover, permanent water areas and the digital elevation model of the land, with appropriate spatial accuracy (all information with spatial accuracy less than 100 meters) has been used. Fast access to processed satellite images, as well as general coding and processing of images and the implementation of the considered methodology in the Earth-engine environment are the main advantages of this study.