Hadi Eskandari Damaneh; Hamid Gholami; Rasool Mahdavi; Asad Khoorani; Junran Li
Abstract
In this study, water use efficiency index (WUE) was used to assessing the effect of drought on the carbon and water cycle. To calculate this index, we used the gross primary product (GPP) and evapotranspiration (ET) products obtained from the MODIS sensor, and the trend of their changes and reaction ...
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In this study, water use efficiency index (WUE) was used to assessing the effect of drought on the carbon and water cycle. To calculate this index, we used the gross primary product (GPP) and evapotranspiration (ET) products obtained from the MODIS sensor, and the trend of their changes and reaction of this index to drought were calculated for the period 2017-2001 in Fars province. Finally, we assessed the land degradation and desertification in different land uses for study area. The results showed that the indices of evapotranspiration, GPP, water use efficiency, and drought increased by 75.25%, 29.9%, 78.51%, and 67.23%, respectively. The effects of drought on evapotranspiration in agricultural lands and grasslands showed more than 67% positive relationship and also, in these land uses, we observed a significant positive relationship (33.4% and 12.5% for the agricultural lands and grassland, respectively). However, in shrubs lands, and savannas, it is more than 66.6% and 87.5%. The effect of drought on water use efficiency in grassland showed that more than 87% of these areas have a positive relationship. The effectiveness of water use efficiency in plants shows a positive relationship in 40.9% in this area, of which only 0.9% has a significant positive relationship. The negative relationship of this land use is about 59.1% of it. Of this negative amount, only 1.6% of the area had a significant negative relationship. The study of this relationship in the use of savannas shows 75% of this area, which includes 1.5 square kilometers.
Sayyed Alireza Hosseini; Hassan Khosravi; Hamid Gholami; Yahya Esmaeilpour; Artemi Cerda
Abstract
In this study, land use change trend in coastal areas of south of Iran, including Sistan Baluchestan, Hormozgan, Bushehr were studied during 31 years (1988-2019). Landsat satellite images including TM, ETM +, OLI were used for this purpose. The maximum likelihood method was also used to classify satellite ...
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In this study, land use change trend in coastal areas of south of Iran, including Sistan Baluchestan, Hormozgan, Bushehr were studied during 31 years (1988-2019). Landsat satellite images including TM, ETM +, OLI were used for this purpose. The maximum likelihood method was also used to classify satellite images. Vegetation indices (SAVI) and salinity index (SI1) were used to influence land use classes on land degradation and desertification. The results of land use change trend showed that Changes in land use classes of man-made areas and saline lands as the most dynamic land use classes followed an increasing trend of 2.72% and 1.14%, respectively. The results of multivariate regression analysis showed that three vegetation, saline and man-made variables, and four vegetation, saline, man-made and sandy areas explain 22.3% and 37.8% of the dependent variables of vegetation and salinity indices, respectively. Therefore, in more than 60% of changes, other environmental variables are affected. Hence, with respect to the results of land use area and regression analysis and the mean trend of SAVI and SI1 changes, where vegetation and SAVI classes show decreasing trend and saline land and SI1 classes have increasing trend, it can be concluded that land use changes is phenomena that changes ecosystem services with almost irreversible impacts. This will have nothing to do with disturbing the ecosystem balance and intensifying land degradation in coastal areas.
saeid barkhori; rasol mahdavi; gholamreza zehtabian; hamid gholami
Abstract
The overuse of fossil fuels, population growth and other factors have caused evident changes in the Earth climate. In this study, HadCM3 model was used to evaluate changes in the variables of precipitation, minimum and maximum temperatures at Jiroft plain in future periods. Afterward, climatic variables ...
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The overuse of fossil fuels, population growth and other factors have caused evident changes in the Earth climate. In this study, HadCM3 model was used to evaluate changes in the variables of precipitation, minimum and maximum temperatures at Jiroft plain in future periods. Afterward, climatic variables was simulated by the LARS-WG model in the periods of 2011-2030 (horizon 2020) and 2046-2065 (horizon 2055) under three scenarios of A1B, A2 and B1. The results showed that the highest amounts of minimum and maximum temperatures will occur based on three scenarios A1B, A2 and B1 in the horizon of 2055. By comparing the average of the monthly minimum and maximum temperatures in the base period (1989-2010) and future periods (under the scenarios of A1B, A2 and B1), the average temperature will increase in the most months of the year. During the scenarios of A1B, A2 and B1, the most annual precipitation will occur in the horizon of 2020. The average amounts of monthly precipitation will increase in the months of January, August, September, October, November and December and will decrease in the other months. Comparing long-term annual precipitation shows that the lowest amount of precipitation will happen under the scenario of B1 and during the period of 2046 to 2065. However, the most precipitation will happen under the scenario of A1B and during the 2011-2030 period.
