مجله مدیریت بیابان
پیاپی 16 (پاییز و زمستان 1399)

Wind erosion and sand dunes mobility has adverse environmental consequences. Identification of factors affecting sand dunes mobility and predicting their future status is essential to control the desertification process. Therefore, in the present study, the mobility of flowing sands in the southeast of Qazvin province has been studied and analyzed. For this purpose, hourly wind speed data, dust phenomenon code, rainfall and temperature of Buin Zahra station were used for the statistical period of 2006-2006. Rainfall and temperature data were used to calculate the rate of evapotranspiration Thornthwaite method. After calculating the percentage of erosive winds and aridity index, by using Lancaster index, the mobility of flowing sand in the southeast of Qazvin province was investigated and analyzed. Sensitivity analysis test was used to predict the effect of climate change on mobility of sand dunes. Results showed that sand dunes mobility was inactive in previous years and activated in recent years. Examining the relationship between the number of dusty days and the Lancaster index using two-variable linear regression showed that there was no strong and significant relationship in the study period between these two parameters, while a significant relationship between Lancaster index and aridity index. These results indicate that 42% of the changes in the Lancaster index were due to changes of the aridity index. The results of the sensitivity analysis showed that if the average of the wind speed and evapotranspiration rate increased by 30% in future, or amount of precipitation decreased by 30%, the status of the sand dunes mobility would change from inactive to active and crossing this threshold could be the reforming of wind erosion activities in the area.

In this study, the average climate data of meteorological stations including temperatures of the warmest and coldest months of the year, precipitation regime, potential evapotranspiration and UNEP aridity index has been used to map Iran's climate zones. In this regard, climate variable of air temperature, relative humidity, potential evapotranspiration, and precipitation characteristics of 303 meteorological stations throughout Iran was used on monthly and annual time’s scales. The annual aridity index in each site was calculated using the United Nations Environment Program (UNEP) index. Then, the temperature characteristics of the warmest and coldest months of the year were coded. Results show a very high climatic diversity throughout Iran. In this model, Iran's climate was divided into 27 categories. Based on aridity index, Iran has seven climates zones. There are 30 cities with hyper-arid climate. This climate type has three climate territories and occupies about 3.4 percent of the country's territory. The arid zone with five climate territories cover about 23.7 percent of the country and dominates 95 cities. The semi-arid climate with 6 climatic territories accounts for about 39.6 percent and dominates 113 cities. The dry sub-humid zone with four climate territories and covers about 17.3 percent and dominates 30 cities. Nine cities have a semi-humid climate with three climatic territories which accounts for about 8.9%. The humid climate with four climate territories covers about 5.8 % and dominates 13 cities. The very humid climate with 2 climatic territories accounts for about 1.3% and represents the climate type of the 12 cities.

Road networks as an integral part of the transportation infrastructure have deleterious ecological effects on habitats and wildlife populations. Vicinity impacts of road networks on habitats together with habitat fragmentation have caused decrease in habitat quality, biodiversity decline. Road networks development is one of the most important risk elements for valuable habitats and species of the Chaharmahal & Bakhtiari province. So, it is necessary to evaluate habitat’s condition and ecosystem services into conservation systematic planning and minimizing its negative impacts. For this purpose, first, the habitat quality of Ovis orientalis Gmelin, (subspecies isphahanica Nasonov), Panthera pardus Pocock, and Ursus arctos Linnaeus,were modeled using Integrated Valuation of Environmental Services and Tradeoffs (InVEST). Then, the vicinity impacts of road networks was assessed using the Vicinity Impact index. To assess the efficiency of the current protected areas network and identifying the priority areas for conservation the Marxan software was used. Results revealed that a large area of the Ch & B province were considered as the suitable habitats for target species. However, high density of the road networks affect 14% of the Ch & B ares which increased the impotance of identifying the prioirity areas in terms of high ecological values and low vicinity impact. The results also showed that eastern, western, and southwestern parts of the province have high ecological values and low vicinity impact. Approximately, 28% of these areas are currently protected which showed the relative efficiency of the current protected areas network.

In order to increase efficiency and prevent the waste of limited capitals of combating desertification projects, there is always no a way that could consider different criteria, strategies and among them, based on a systematic structure and group perspective, offers the optimal solution. The aim of this study was to present a method to rank the optimal strategies to combat desertification in the Yazd-Khezrabad plain based on Multiple Attribute Decision Making model (MADM) using Linear Programming Techniques for Multidimensional Analysis of Preferences (LINMAP) model. In this method, by finding the Euclidean distance of the strategies with the best strategy, the most preferred strategy was selected. In this regard, the problem was transformed into a linear mathematical model, which after running the model in the LINGO software environment, the weight of each strategy, the distance from the ideal strategy and the ideal strategy were estimated. From a LINMAP evaluation model perspective, based on the preference results of five criteria surveyed including Environmental compatibility (C7), environmental and human resource degradation (C16), specialized human resources (C6), scientific and technological tools (C5) and time (C2), the strategies of vegetation regeneration and rehabilitation " (A23), "prevention of inappropriate land uses change" (A18) and "adjustment in groundwater abstraction" (A31) with a distance of 16.20, 16.22 and 16.35 were selected as the most important strategies to combat desertification in the region, respectively. The results of present study enable the desert managers to utilize limited resources and budget dedicated to control desertification process in a correct and efficient manner. Therefore, the results of the mentioned ranking can increase the success rate of combating desertification and land reclamation projects in the study area.

Human societies are considered as a part of ecosystems. The interaction between human societies and ecosystems has consequences for them. Desert ecosystem is one of the common ecosystems in arid regions of Iran. In desert, phenomena such as drought affect the lives of human societies. The present study analyzes the effect of hydrological drought on resilience of human communities in Yazd province. Hydrological drought was studied based on river flow index and resilience of human communities using economic, social and environmental criteria by using principal component analysis method. The factor was calculated based on the values of the rotated matrix and the eigenvector values. Multiple linear regression analysis of drought effects on factors was investigated. Analysis of the relationship between drought and resilience indicates a significant relationship between them. The most affected sectors by drought were economic, social and environmental, respectively. The most important economic losses were the variables of employment share in services and industry sectors, rural income and cost, irrigated agriculture, area under cultivation, urban cost, participatory economy rate. The overall results of combining the drought index with socio-economic and environmental indicators indicate an increase in vulnerability and a decrease in the resilience of human societies due to drought. Lifestyle and direct dependence on ecosystem resources should be reconsidered. In other words, generating processing, conversion and complementary industries, extends the chain of drought dependence and exploitation to reduce drought fluctuations.  Diversifying the use of ecosystem services and replacing them in times of drought events can increase the resiliency of human societies.

Surface soil moisture is one of the important variables in hydrological processes that affects the exchange of water and energy flow in relationship between land surface and atmosphere. Precise assessment of spatial and temporal variations in soil moisture is crucial for numerous environmental studies. Recent technological advances in satellite remote sensing indicates that the soil moisture can be measured using remote sensing methods. The purpose of this study is to estimate biophysical indices and evapotranspiration using SEBAL algorithm and to present soil moisture index using principal component regression method in the east of Bakhtegan Lake, Fars province. For this purpose, five Landsat 8 satellite images for March, April, May and June 2017 were selected and initially corrected. Meteorological data of Marvdasht synoptic station was used to execute SEBAL algorithm. Soil moisture index was modeled using biophysical indices such as albedo, net radiation flux, soil heat flux, evapotranspiration, and etc. by using principal component regression. TVDI index was used to validate the model. The coefficient of determination (R2) and F index are equal to 0.966 and 1651581.9, respectively, which indicates the high efficiency of the model to obtain soil moisture index for each pixel in different areas with different conditions and diverse vegetation. In addition to temperature and vegetation, other biophysical indicates of the region that affect the soil moisture should be taken into account.

The aim of this study is to evaluate the land cover changes in the basin of Sefiddasht-Borujen using remote sensing Using remote sensing data, land cover maps of satellite images of 1998, 2009, and 2018 were prepared and classified. Then, using the image differencing method, land cover changes for the time periods of 1998 to 2018 were detected. Finally, predicted land cover changes were investigated in each land cover using a CA-Markov model. To predict the probable changes for the year of 2028, the 2018 land cover was modeled using 1998-2009 images by applying of the CA-Markov method of change detection. Next, the resulted of modeled 2018 land cover map were compared with the ground truth map of this year. The results of both maps showed relatively similarity and there was a slight difference between these predicted and classified images of 2018. Therefore, this method was used to predict 2028 land cover image too. The results of change detection for the years 1998 to 2018 indicates the reduction of 8339 hectares of agricultural lands in the study area, as well as 11824 ha from rangelands. Conversely, the bare land increased 14601 ha. According to predicted map for 2028, the largest incremental change in the bare land will be 16476 ha. Estimates show that 8664 hectares of these lands will be from agricultural lands, but approximately 8580 ha will be transformed into the bare land and about 224 ha to residential-industrial lands. Rangelands also will be reduced by13055 ha including 11663 ha to bare land and 1069 ha will be transformed into residential-industrial areas. 16476 ha will be added to bare land and 1420 ha to residential-industrial areas. The results of the present study can be used for future planning for the study area.

Rising atmospheric carbon dioxide is one of the main causes of climate change and its devastating environmental consequences, such as global warming. Soils are the third largest carbon storehouse, and the amount of carbon storage is strongly influenced by the land use management. The aim of this study was to investigate the changes in carbon storage in different land uses included Punica granatum orchard, Medicago sativa farm, rangeland, Hordeum vulgare farm and fallow, under impact of soil properties such as sand, clay, silt, nitrogen, phosphorus, potassium, organic carbon, pH and EC, in Ala area of Semnan. In the selected land uses 30 soil samples were taken in both 0 - 5 and 5 - 30 cm soil depths in three. In order to investigate the effect of land use type in two soil depths studied on soil carbon content, analysis of variance and Duncan's test was used to compare the means. Pearson correlation was used to investigate the relationship between soil properties as independent variables and soil organic carbon as a dependent variable. Also, multiple regression analysis was performed to determine relationship type between the variables. According to the results, the type of land use in both soil depths has a significant effect on soil carbon storage. The highest average soil carbon storage in 0 - 5 and 5 - 30 cm soil depths in alfalfa and pomegranate orchard land uses are 16.14 and 68.11 t/ha, respectively. The lowest amount of carbon storage in 0 - 5 and 5 to 30 cm soil depths related to rangeland use are 6.23 and 16.58 hectare/ha, respectively. Pearson correlation coefficient between organic carbon and soil factors of nitrogen and phosphorus were statistically significant with r of 0.8 and 0.59, respectively. Since the correlation between organic carbon and phosphorus is low, it was omitted in the regression analysis. Finally, the percentage of soil organic carbon was obtained based on the percentage of soil nitrogen. In general, land use change from pasture to arable land and pomegranate orchard can have a significant effect on increasing soil carbon storage in the study area. Soil properties other than nitrogen have no significant effect on soil organic carbon.

The first character of the desert is lack of water as well as the lack of vegetation. Although the number of plant species in arid lands is very limited, but these species have survived and adapted over the centuries. Due to the difficulty of entering Lut desert, during the last one hundred years, no research was done on plant species in Southern Khorasan part. Therefore, during 2017 to 2018, all perennial species in Lut were identified. The results revealed that a total of six species belonging to four genera and three families were identified. Chenopodiaceae with three species, Poaceae with two species and Polygonaceae with one species occupied 50%, 33.3% and 16.66% of the flora of the region, respectively. Stipagrostis and Haloxylon have the highest number of species. Geographical distribution analysis showed that Iran-Turan and Sahara-Sindi species are presented in equal proportions. Haloxylon persicuum Bge. ex Boiss. & Buhes, Haloxylon ammodendron Bunge ex Fenzl and Stipagrostis plumosa Munro exT. Anderson were distributed in the north and northeast. The highest distribution of Calligonum comosum L'Hér was observed in the west. Although the diversity was very limited and the 18-year droughts have intensified the drought of Calligonum and Haloxylon in many areas of Lut, however, increase in rainfall in 2019 in Lut increased hope for the survival of shrubs and increasing the amount of Stipagrostis species.

Climate change affects severity and duration of drought, peak, magnitude, and frequency of the events in the coming decades. Iran is one of the countries that have suffered the most from drought. Therefore, drought monitoring and forecasting is crucial for drought mitigation and preparedness strategies in future. This study was conducted to evaluate the status of drought characteristics of severity, duration, magnitude, and peak in historical period from1966 to 2015 and future from 2016 to 2050  for 39 synoptic stations in Iran using Standardized Precipitation Index (SPI). Also, for future simulation, the output of the general circulation model of CanESM2 based on two scenarios RCP4.5 and RCP8.5 and the statistical downscaling method of SDSM were used. Results showed that the trend of severity, duration, magnitude, and peak  have no any significant trend. The SPI zoning map shows an increase in the historical period but will decrease in the future period under two scenarios. The results of the trend analysis of the severity, duration, and magnitude and peak drought showed that there is no significant trend in the historical and future in Iran. However, most of these characteristics are increasing in the northern, northeastern, western, and southern parts of Iran. Finally, the southern parts of Iran including Hormozgan and Sistan and Baluchestan provinces, the northeastern and western parts of Khorasan Razavi, Golestan, and Azerbaijan provinces will be most vulnerable to climate change. Therefore, the risk of drought in these regions is high and it is necessary to seriously plan for the management of natural resources, and agriculture.

Controlling and managing of seasonal and sudden floods in arid and semi-arid regions, especially in areas where surface water is out of reach is necessary. Flood spreading is one of the best ways to control surface runoff and recharge groundwater resources. In the present study, the appropriate sites for flood spreading project in border area of Taybad county in Khorasan Razavi province is selected using Boolean logic .For prioritization the suitable locations, TOPSIS and VIKOR multi-criteria decision making methods were used. Firstly, using Boolean logic inappropriate areas based were removed on criteria (slopes greater than 8%, urban area, agriculture and covered pediment). Then, 11 zones were selected as the suitable areas of using TOPSIS and VIKOR models based on the criteria  of slope, groundwater quality, geology, alluvium thickness, transmission capability, drainage density, surface permeability, groundwater loss, distance from the village, distance from wells and land use.. Results showed that most suitable areas are located in alluvial fans. Based on the TOPSIS model, location J with value of 0.75 was selected as the best site, and using the VIKOR model, location K with a value of 0.96 was selected as the best location for flood spreading projects.

Climate change is the most important global challenge, particularly in semi-arid regions. The objective of this study was to investigate the effect of changes in climatic parameters on drought and desertification hazard in Kermanshah province, Iran, using precipitation, temperature, evaporation and relative humidity data during period of 1992 and 2018. Desertification risk was assessed through UNEP index. The results of this study showed that during the last decade, climatic elements in Kermanshah province have undergone significant changes. Among all climatic parameters, changes in air temperature were noticeable, so that the maximum, minimum and average temperature at most stations in Kermanshah province has increased significantly. Relative humidity decreased at most stations and precipitation decreased. These changes have been more evident and significant in Kermanshah city than in other parts of the province. The study of SPEI index showed that all part of the provinces impacted by drought and the southwestern areas are facing with more severe drought.The trend of drought changes in Kermanshah province in most parts of the province during the last decade compared to the decades also showed, an increase in the drought intensity and duration and a decrease in the length of wet duration. The desertification risk is observed in north. The highest desertification risk is observed in the southwestern regions of the province, mainly Somar, Naftshar and Ghasreshirin, but the trend of changes only in Kermanshah showed increased desertification risk due to significant changes in climatic elements.