جستجوی مقالات مرتبط با کلیدواژه "land use" در نشریات گروه "هواشناسی"

Evaluation and analysis of changes in environmental variables is an important step in the direction of presenting the components of management decisions. The use of spectral indicators is one of the methods of evaluation, analysis and monitoring of changes. In this research, to evaluate land use changes in Wasit city, in order to investigate the process of land use changes and vegetation, first, images of 3 periods related to Landsat 8 sensor OLI 2018 satellite were prepared and prepared for the necessary pre-processing and processing. Then, using the classification method and applying four plant spectral indices, land use was done in four classes. The investigation of vegetation spectral indices NDVI, NDBI, NDWI and SAVI showed that with the passage of time NDWI and NDVI had a decreasing trend and two indices NDBI and SAVI increased with the passage of time. Kappa index has also been used to evaluate the classification. The results showed that among the four spectral indices under investigation (NDVI, NDBI, NDWI and SAVI), the NDVI spectral index with accuracy percentage of 0.99%, 0.98% and 0.99% during the period from 2014 to 2023, has the highest accuracy in distinguishing vegetation classes. The changes in land use level for each index (NDVI, NDBI, NDWI and SAVI) during the time period from 2014 to 2023 also showed that the highest and lowest levels during this time period are related to NDVI and NDWI index which are equal to 35939.2968 and 541.6227 square kilometers respectively.

Land use and land cover maps are essentially needed for socio-economic development and environment protection. Accurate and up to date maps play an important role in urban planning. Synthetic Aperture Radar (SAR) sensors provides unique information from the Earth surface due to their imaging capabilities in all-weather condition. However, inherent speckle effect limits their application. In this study, the effect of speckle filtering on the land use/land cover (LULC) classification map in Bander-Mahshahr, Iran has been studied. Dual-polarimetric Sentinel 1-A (VH,VV) and multispectral Sentinel-2B were fused for classification purposes. Different speckle removing methods such as Boxcar, Median, Frost, Refined Lee, Lee Sigma, Intensity-Driven Adaptive-Neighborhood, Gamma Map, and Lee filters were applied on the Sentinel-1A dataset. The Gram–Schmidt (GS) fusion process was chosen to integrate the multispectral Sentinel-2 data and VH, VV bands of Sentinel-1 data. Then, the LULC (land use/land cover) was produced with a random forest classifier. IDAN filter has reached the highest overall accuracy (i.e., 76.64%) and Kappa coefficient (i.e., 0.72) on the combined VH polarization image and sentinel-2 bands. Also, in combining VV polarization with Sentinel 2 bands, the median filter provides the highest performance with overall accuracy of 76.6% and Kappa coefficient of 0.7. As the study area is located in a coastal environment and there is frequent cloud cover, the combination of two polarizations VV and VH without using Sentinel-2 bands was also studied. The highest performance was provided by the boxcar filter with an overall accuracy of 95.56% and a Kappa coefficient of 0.94. The obtained results confirm the high capabilities of SAR images in LULC mapping in a coastal city

In this study, salinity prediction of Karkheh River after exploitation of irrigation and drainage projects of Jahad Nasr Institute was investigated using SALTMED salinity simulator model. Due to climatic conditions, cultivation pattern, irrigation schedule, soil and water characteristics and drainage of the Evan, Dowsalagh, Arayez and Bagheh plains that are excluding the Upper Plains, the volume of drainage output and the amount of salt produced from each plain with a total area of 55,000 hectares were simulated. Also from the data, the years (2013-2017) were used due to completeness of the information. The results showed that based on the prediction of the SALTMED model in the statistical year 2013; the amount of 150, 87, 140 and 197 thousand tons of salts enter the Karkheh River annually from the Evan Plain, Dowsalagh, Arayez and Bagheh, respectively. If the same trend continues for 10 years, an amount of 5.74 million tons of salt will enter Karkheh and then eventually discharge into the Hawizeh Marshes, which will have many environmental impacts. The overall result showed that by exploiting 37,000 hectares of 55,000 hectares in the four plains, the Karkheh water salinity index (EC) increased significantly and on average, it will reach from 1.15 dS/m to more than 2 dS/m. Now, if all 55,000 hectares or more of the 550,000 hectares of land were exploited, how much salt and drainage water would flow into the rivers?

The sea-land breeze is a common atmospheric phenomenon in coastal regions that occurs due to the difference of specific heat capacity between water and soil. In this paper, characteristics of the sea-land breeze in Booshehr is investigated, using some analytical models and Sodar data in Booshehr station located in the North of Persian Gulf. These data belong to some days in September, October, November and December 200. The observation and calculation are well coordinated and show that the average depth and horizontal scale are 350 m and 41 km separately. Also the observations show that the sea-land breeze has occurred in most days of the months and the observed data indicate that 70% of the occurrence are during the months September, November, December and 65% of in the month of October.