نشریه خشک بوم
سال چهاردهم شماره 2 (پاییز و زمستان 1403)

The Mesopotamian Plain is one of the common water basins in the Middle East region, which has witnessed major ecological and hydrological changes in recent decades. Therefore, the extensive drying of the water areas of this plain has led to the widespread destruction of the region's ecosystem and the unprecedented expansion of the desert. Based on this, in this study, the trend of changes in the water areas of the inter-Nahrin plain during the last four decades using satellite images and evaluating the severity of drought and the changes in rainfall caused by it using SPI indicators. RAI and PNI were paid during the years 1989 to 2022. As the results showed, during these years, due to various factors, including climate changes, decrease in rainfall, drought, dam constructions by Turkey, etc., led to an increase in the decreasing trend in water areas and as a result, the spread of droughts. It has been done in this calvary. In addition, the drought situation during the years 1980 to 2022 based on the average rainfall and also the percentage of SPI, RAI and NPI indicates that the most droughts are related to the decades of 1990-2000 and 2007-2015 and the continuation of droughts until 2022 can be seen in the south and southeast and to some extent in the west and southwest of the country. Therefore, proper planning is needed in order to control the drought in the region and then environmental consequences such as it is necessary to increase dust and other biological consequences in the country.

Awareness of vegetation and climate changes is necessary for the correct planning of ecosystem management. In the present study, the temporal and spatial changes of vegetation cover and also land surface temperature and precipitation parameters in the natural vegetation cover of different bioclimates of Isfahan province from 1986 to 2022 were investigated based on  Google Earth Engine system, Landsat satellite and PERSIANN-CDR data. The trend and the amount of changes of these parameters were obtained with the Mann-Kendall and Sen's slope tests. The results showed that the minimum amount of NDVI vegetation was 0.26 in arid and warm climate in 2022 and its maximum was 0.90 in humid and cold climate in 2002. The lowest and highest of land surface temperature was obtained in humid and cold climate and warm and arid climate as 290.61 and 328.54 Kelvin in 2003 and 2022, respectively. The minimum and maximum precipitation were 88.72 mm and 598.17 mm in 2004 and 2001, respectively, in the semi-arid and warm climate and humid and cold climate. The Z statistics of Mann -Kendall test and the amount of Sen's slope for the parameters of vegetation and temperature in most climates were decreasing and increasing, respectively. A decreasing trend with high statistical significance of precipitation was observed only in humid and cold climate (Z equal to -2.08 with a slope of -3.34). In general, the results showed that the vegetation of the province is decreasing, but the temperature is increasing.

Access to groundwater resources as one of the highest quality water sources has always been of interest to residents of dry and desert areas around the world. This essential need has led to the drilling of wells in most of the basins in these areas. On the other hand, the evaporation process from water sources such as wells and qanats also leads to losses and water shortages in dry and desert areas, which are often not considered in water resource management. Therefore, measuring the rate of evaporation from wells and qanats as the most important water sources in dry and semi-arid areas is the main approach of this research. The present study aims to measure the rate of evaporation from wells and qanats and analyze the results of expert surveys regarding the selection of the most suitable methods to reduce evaporation from wells using a hierarchical analysis method or AHP through questionnaire analysis and the results obtained were analyzed using Expert Choice software. This research was conducted in two parts: field operations and installation of four standard gypsum blocks with dimensions of 5 × 3 × 7 cm at depths of 30 cm (well mouth), 1 meter away from the well, 20 meters away from the well, 40 meters away from the well, and measuring and comparing the moisture percentage, as well as laboratory experiments. The results of measuring the moisture percentage in the wells under study showed that with an increase in distance from the well mouth, the moisture decreases, and with an increase in well depth, the moisture percentage increases. The moisture absorbed by the gypsum block inside the moist and water-rich well was higher than the dry wells, including sewage wells. Furthermore, the results of comparing the main criteria in the Expert Choice software showed that the highest weight was related to the type of well (0.66) and the lowest weight was related to the time criterion (0.04). The well depth (0.20) and the type of sediments (0.08) were ranked third and fourth in priority, respectively. The comparison of sub-criteria of the type of well led to the placement of qanat rods in the first rank with a weight of 0.687 and sewage wells in the fourth rank with a weight of 0.127. The comparison of time sub-criteria led to the placement of the summer season in the first rank with a weight of 0.496 and the night in the fourth rank with a weight of 0.04. Based on the sub-criteria of sediment type, the covered basin had the highest weight (0.729) and the bare basin had the lowest weight (0.109). Overall, most experts believed that unused and unexploited wells should be filled. However, they had different opinions on the three parameters under study, with well capping having a higher priority in reducing evaporation from wells with a weight of 0.709, and well mouth capping being the lowest priority with a weight of 0.113.

Considering that, the majority of Iran's land area falls within arid and semi-arid regions, the use of plants resistant to salinity and drought stress can provide a new opportunity for adaptation to the country's highly stressful climates. Therefore, this research aimed to investigate the effects of different levels of drought and salinity on the survival and morphophysiological characteristics of one-year-old Russian olive seedlings. An experimental pot study was conducted in a completely randomized block design with three replications and three observations, at three levels of drought (control 100%, 66%, and 33% field capacity) and four levels of salinity (zero as control, 4, 8, and 12 dS/m) in the greenhouse of the Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran, from August to November 2021, over a period of 4 months. In this study, the traits of fresh and dry weight of roots and above-ground parts were measured. The results showed that the main and interactive effects of drought and salinity stress on the measured traits were significant. Only the interactive effect of drought in salinity on root dry weight was not significant, and an increase in the main and interactive effects of drought and salinity stress resulted in a decrease in both fresh and dry weights of roots and above-ground parts. The lowest values of the measured traits were observed as follows: fresh weight of above-ground parts (13.9 g), dry weight of above-ground parts (4.3 g), fresh weight of roots (12.5 g) in the treatment of 12 decisiemens salinity and 33% dryness and dry weight of roots (3.5 g) with 33% dryness and 8 decisiemens salinity.

Examining the trends and characteristics of the affected areas is essential to effectively control and contain wind and dust erosion. This study focuses on Sarakhs County and aims to achieve this by integrating remote sensing and ground-based data. The trend of vegetation changes was analyzed using Landsat satellite images and the MSAVI index from 1995 to 2023 within the Terrst2020 environment. The intensity of wind erosion in the affected areas, including sand extraction, transport, and deposition, was identified and classified using satellite images and field surveys based on sand dune origination guidelines. By integrating the maps obtained from these steps, the location and characteristics of the degraded lands were determined. The study revealed that the average MSAVI index decreased from 0.209 in 1995 to 0.137 in 2004, indicating a decline in vegetation cover. The harvesting, transportation, and sedimentation areas accounted for 50.1%, 24.6%, and 2.4% of the degraded areas, respectively. Most of the degraded regions (88%) were in agricultural lands, primarily low-yield rainfed lands. Only 6% of the degraded areas were in pasture lands, while 48.4% were in man-made forests. It is evident that land use changes, particularly the conversion of pastures to low-yield rainfed lands, are the main drivers of land degradation and desertification, leading to increased wind erosion and dust in Sarakhs County. Therefore, practical solutions should prioritize the management of low-yield drylands through conservation agriculture and restoring degraded rangelands with the participation of local communities.

This research investigates the barriers farmers face in adapting to drought. The statistical population comprises all farmers in Bavi County. Using cluster sampling with proportional assignment based on the Kerjesi and Morgan table, a sample size of 350 farmers was selected. The primary research tool was a questionnaire with a Likert scale, validated by a group of subject experts and confirmed for reliability using Cronbach's alpha coefficient and composite reliability. Data were analyzed using both descriptive and inferential statistics via SPSS and Lisrel software. The results indicated that some farmers lacked a proper understanding of drought, rainfall, and temperature patterns in the region. Moreover, "land leveling" and "use of local knowledge" emerged as the most important strategies for adapting to drought. The main obstacles identified were "lack of access to timely weather information" and "lack of access to water resources." Finally, confirmatory factor analysis classified the obstacles into economic, infrastructural, technical and informational, and social-human factors.