https://deej.kashanu.ac.ir/ Desert Ecosystem Engineering en daily 1 Sun, 23 Aug 2026 00:00:00 +0330 Sun, 23 Aug 2026 00:00:00 +0330 https://deej.kashanu.ac.ir/article_115623.html Climate change, largely driven by anthropogenic activities, has intensified the frequency and severity of extreme weather events, including floods, droughts, hailstorms, heatwaves, and anomalous cold spells. This study evaluates the performance of three CMIP6 models (ACCESS-CM2, MIROC6, and NESM3) in simulating daily precipitation and temperature for the flood-prone Gharesou watershed in Ardabil, Iran. The models were validated against observed data from 1984–2014 using statistical metrics, including Root Mean Square Error (RMSE), Percent Bias (PBIAS), and the Nash-Sutcliffe Efficiency (NSE). Following validation, future projections were downscaled and bias-corrected under SSP1-2.6, SSP2-4.5, and SSP3-7.0 scenarios using the delta change method. Based on the superior performance in PBIAS and NSE metrics across all stations—with minor exceptions in specific precipitation and maximum temperature parameters at the Ardabil and Namin stations—the ACCESS-CM2 model was selected for long-term projections. The results indicate a general downward trend in monthly precipitation, with localized exceptions during the June–August period in Ardabil, March–August at the Airport station, and July in Namin and Nir. A comparative analysis between observed and projected mean annual precipitation under the SSP1-2.6 scenario reveals site-specific variations: declines of 31.07 mm, 37.60 mm, and 116.69 mm at the Ardabil, Namin, and Nir stations, respectively, alongside a marginal increase of 1.44 mm at the Ardabil airport station. Furthermore, all scenarios project a consistent rise in mean annual maximum and minimum temperatures. Specifically, the projected increase in maximum temperature ranges from 1.2 °C (SSP2-4.5, Ardabil) to 2.05 °C (SSP1-2.6, Namin), while minimum temperatures are expected to rise by 3.65 °C (SSP2-4.5, Namin) to 7.75 °C (SSP1-2.6, Ardabil airport). These forecasts, characterized by decreasing precipitation and significant warming, underscore the likelihood of imminent climate-driven extremes. Consequently, these findings provide a critical foundation for water resource managers to develop targeted risk mitigation strategies and enhance environmental and hydrological resilience in the region. https://deej.kashanu.ac.ir/article_115654.html Introduction This study provides a dynamic projection of seasonal and annual dust aerosol distributions over Iran using the coupled RegCM4 regional climate model under the RCP4.5 emission scenario for the 2030–2040 and 2050–2060 horizons. This research addresses a critical knowledge gap, as previous assessments in Iran have largely relied on global model outputs or simulations of historical conditions without the benefit of dynamical downscaling. By employing a high-resolution regional climate model (RCM) capable of resolving local-scale physical processes, this study captures the complexities of dust emission, atmospheric transport, and deposition, offering a more nuanced understanding of future dust dynamics in the region. Methodology The study utilized boundary conditions derived from global RegCM climate simulations, with 6-hourly temporal resolution extending to 2100. The RegCM4 model was configured with a 40-km horizontal grid resolution, balancing computational feasibility with the requirement to resolve major regional dust sources. Simulations were driven by the RCP4.5 scenarios—representing a moderate greenhouse gas emission pathway—covering the Iranian domain (25°N–45°N and 44°E–64°E). Key physical parameterizations included the Emanuel convection scheme, the Holtslag planetary boundary layer scheme, the NCAR-CCM3 radiation scheme, and the BATS1e land surface scheme. Following a 3-month spin-up period to ensure initialization stability, decadal averages for 2030–2040 and 2050–2060 were analyzed to determine dust trends. Results The modeling results successfully identified multiple internal and external dust hotspots. Internal sources were notably active in Sistan and Baluchestan, Kerman, South/Razavi Khorasan, Khuzestan, Bushehr, Hormozgan, and Isfahan provinces. Among these, the Sistan and Baluchestan and Khuzestan regions exhibited the highest frequency and intensity of dust events. External dust contribution was found to be significant from northern Saudi Arabia, the Iraq-Kuwait border, and northeastern regions adjacent to Turkmenistan. Seasonal analysis highlighted distinct behaviors: Sistan and Baluchestan remains active year-round, with peak intensities in autumn and winter linked to the strengthening of the Levar wind system. Conversely, the Khuzestan source, characterized by extensive dry marshlands, exhibits peak mobilization in spring due to the Shamal wind system, which facilitates dust transport from the Tigris-Euphrates basin. Discussion and conclusion The projections indicate a clear intensification in both dust production volumes and event frequency throughout the 2030s and 2050s, driven by climate-change-induced declines in soil moisture, altered vegetation cover, and intensified wind patterns under RCP4.5. Furthermore, the identification of emerging dust sources in Turkmenistan poses a heightened risk to northeastern Iran. While the model successfully delineates regional hotspots, it is subject to spatial constraints; the 40-km resolution limits the detection of localized sources smaller than 1,600 km². Consequently, while the model provides a robust assessment of regional-scale dynamics, smaller sources may be underrepresented or smoothed. Despite this, the study’s findings corroborate the urgent need for transboundary cooperation and localized dust mitigation strategies. These results suggest that by 2054, Iran will experience a shift toward significantly warmer and drier conditions, necessitating the integration of these projections into national water resource management and sustainable land-use planning. https://deej.kashanu.ac.ir/article_115548.html Introduction Groundwater depletion has emerged as a critical challenge in arid and semi-arid regions, driven by the synergistic effects of agricultural expansion, rapid population growth, climate variability, and unsustainable abstraction practices. In Iran, where agriculture accounts for approximately 90% of total water consumption, diminishing precipitation and prolonged droughts have severely intensified pressure on aquifer systems. The Qorveh–Dehgolan basin, located in northwestern Iran, serves as a prominent example of a highly stressed system where persistent water deficits and over-exploitation of groundwater have led to significant declines in aquifer storage. Given projected climate change scenarios, reduced surface water availability and escalating water demand are expected to further exacerbate groundwater stress. Consequently, evaluating the efficacy of integrated demand-side management strategies is essential for achieving long-term water sustainability. This study aims to quantitatively assess the impacts of individual and combined demand management scenarios on groundwater storage dynamics in the Qorveh–Dehgolan basin under both historical and projected climate conditions. Materials and Methods The Qorveh–Dehgolan basin covers approximately 7,246 km² and includes three main alluvial aquifers: Dehgolan, Qorveh, and Charduli. Water demands are dominated by agriculture, which accounts for more than 95% of total annual water use, while domestic and industrial demands are fully supplied by groundwater. The integrated Water Evaluation and Planning (WEAP) model was applied to simulate surface water–groundwater interactions over the historical period 2007–2021. Model calibration and validation were conducted using observed streamflow data at the Hasan Khan hydrometric station, yielding satisfactory performance (NSE = 0.82 for calibration and 0.79 for validation). To assess future climate impacts, outputs from three CMIP6 global climate models under SSP2.6, SSP4.5, and SSP8.5 scenarios were downscaled using the LARS-WG weather generator for the period 2026–2045. The IHACRES rainfall–runoff model was employed to estimate future inflows to the Soural, Siah-Sang, and Ghocham reservoirs, and these inflows were incorporated into the WEAP model. Five groundwater demand management scenarios were defined and simulated: (1) installation of smart water meters, (2) sealing of illegal wells, (3) revision of groundwater abstraction permits, (4) regulation of unlicensed wells, and (5) a combined scenario integrating all measures. The impacts of these scenarios on aquifer storage trends were quantitatively evaluated. Results The Qorveh–Dehgolan basin, spanning approximately 7,246 km², encompasses three primary alluvial aquifers: Dehgolan, Qorveh, and Charduli. Water consumption is predominantly agricultural, accounting for over 95% of total annual demand, while domestic and industrial requirements are exclusively met through groundwater extraction. To simulate surface water–groundwater interactions, the Water Evaluation and Planning (WEAP) model was employed for the 2007–2021 historical period. The model was calibrated and validated against observed streamflow data at the Hasan Khan hydrometric station, demonstrating satisfactory performance (Nash–Sutcliffe Efficiency [NSE] = 0.82 and 0.79, respectively). To project future climate impacts, outputs from three CMIP6 global climate models under SSP2.6, SSP4.5, and SSP8.5 pathways were downscaled using the LARS-WG weather generator for the 2026–2045 period. Furthermore, the IHACRES rainfall–runoff model was utilized to estimate future inflows to the Soural, Siah-Sang, and Ghocham reservoirs, which were subsequently integrated into the WEAP framework. Finally, five demand-side management scenarios were simulated: (1) installation of smart water meters, (2) decommissioning of illegal wells, (3) revision of groundwater abstraction permits, (4) regulation of unlicensed wells, and (5) a combined scenario encompassing all aforementioned measures. The potential impacts of these strategies on aquifer storage trends were quantitatively assessed. Discussion and Conclusion Our results demonstrate that groundwater depletion in the Qorveh–Dehgolan basin is primarily driven by agricultural water deficits, a trend likely to intensify under projected climate change. While individual demand-side measures yield measurable benefits, their isolated implementation remains insufficient to effectively counteract long-term aquifer depletion. The superior performance of the combined scenario underscores the necessity of integrating regulatory, technical, and monitoring-based interventions to achieve significant groundwater recovery. Notably, the volume of groundwater saved under the combined scenario closely approximates the average annual agricultural water deficit in the basin, suggesting that comprehensive demand management can substantially mitigate pressure on both groundwater and surface water resources. This finding is particularly salient in regions characterized by pronounced summer aridity, where groundwater serves as a critical buffer against seasonal water scarcity. Ultimately, this study confirms that an integrated approach to groundwater demand management provides a robust and pragmatic pathway toward hydrological sustainability in water-stressed basins. The proposed framework not only addresses current depletion but also enhances long-term resilience to climate variability. Furthermore, these findings offer transferable insights for other arid and semi-arid regions in Iran and beyond, where comparable hydro-climatic and socio-economic conditions prevail. https://deej.kashanu.ac.ir/article_115549.html Introduction Global atmospheric warming is fundamentally altering atmospheric circulation patterns, which directly influence wind regimes and their associated variability. Consequently, climate change is anticipated to exert a significant impact on future wind characteristics and, by extension, the reliability of wind energy resources. Given that wind power density is highly sensitive to wind velocity, even marginal shifts in wind speed can substantially affect offshore wind energy generation. Despite the rising global prominence of offshore wind energy, the specific impacts of climate change on power density and energy potential within the Persian Gulf have received limited academic attention. To address this research gap, the present study evaluates the impacts of climate change on offshore wind energy potential in the coastal region of Bushehr, situated in the northern Persian Gulf, under various projected climate scenarios.   Materials and Methods This study aims to assess the clean energy generation potential of offshore wind turbines along the Bushehr coastline and to project future energy extraction capacity under CMIP6 climate scenarios. Historical wind speed data (1980–2024) were retrieved from the Bushehr coastal meteorological station. Future wind patterns for the 2025–2050 period were simulated using the CESM2 global climate model under SSP2-4.5, SSP3-7.0, and SSP5-8.5 forcing scenarios. To characterize wind speed distribution, wind power density (WPD), and energy potential for both historical and future periods, the Weibull distribution function—characterized by its shape (k) and scale (c) parameters—was applied. WPD was computed at the turbine hub height, and annual electricity generation potential was estimated based on the deployment of 5 MW offshore wind turbines. Furthermore, the InVEST offshore wind energy model was utilized to evaluate energy production capacity, socio-economic indicators, and carbon offset potential under both baseline and projected climate conditions.   Results Analysis of wind speed anomalies in the coastal regions of Bushehr revealed a transition from predominantly negative anomalies during 1980–2000 to positive anomalies post-2000, indicating a trend toward intensification of wind conditions in recent decades, with peak anomalies observed during 2010–2015. Climate projections suggest that rising air temperatures will likely intensify offshore wind speeds across the Persian Gulf. Relative to the baseline period (1980–2024), mean wind speed is projected to increase from 5.78 m/s to 6.1, 6.3, and 6.7 m/s under the SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively, representing growth rates of approximately 6%, 8%, and 14%. Consistent with these shifts, wind power density (WPD) is projected to experience substantial growth under future climate conditions. Compared to the baseline, WPD is expected to rise by approximately 20%, 23%, and 27% under the respective SSP scenarios. Incorporating bathymetric constraints and turbine installation costs, our findings indicate that a single 5 MW offshore turbine, which generates approximately 17.79 GWh/year under baseline conditions, could see its energy output increase by 13% to 21% depending on the climate pathway. Similarly, a 20-turbine wind farm, currently capable of generating ~355 GWh/year, is projected to experience a capacity increase of 13% to 22%. Finally, the Levelized Cost of Energy (LCOE), estimated at 0.015 USD/kWh in the baseline period, is projected to decline to approximately 0.011, 0.010, and 0.013 USD/kWh under the SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively, highlighting the enhanced economic viability of offshore wind energy in the region under future climate projections.   Discussion and Conclusion Offshore wind energy has experienced rapid global expansion, driven by superior wind resource availability and proximity to coastal demand centers. This study demonstrates that the Bushehr coastal region possesses significant offshore wind energy potential, which is projected to persist—and potentially enhance—under evolving climate conditions. Our findings indicate that anticipated increases in wind speed and power density will likely bolster energy generation capacity, thereby improving the economic feasibility of offshore wind projects in the region. The results further suggest that deploying twenty 5 MW offshore turbines within 15 km of the Bushehr coastline could generate approximately 355 GWh/year of clean electricity, effectively offsetting nearly 0.24 million tons of carbon emissions annually. Compared to fossil-fuel-based power generation in Iran, this transition offers substantial environmental benefits. Furthermore, our uncertainty analysis, utilizing Monte Carlo simulations, reveals notable variability in the Levelized Cost of Energy (LCOE). Complementary tornado analysis identifies wind speed as the most influential driver of LCOE, underscoring the critical importance of accurate wind resource assessment for project economics. Overall, these findings highlight the immense potential of the Bushehr coastline as a strategic hub for sustainable offshore wind development, providing a robust pathway for diversifying Iran’s energy portfolio while mitigating climate-related risks. https://deej.kashanu.ac.ir/article_115730.html Extended Abstract Introduction: Rangelands are vital ecosystems that provide forage and high-value by-products such as medicinal plants. Given population growth and limited forage resources, promoting medicinal plants, beekeeping, ecotourism, and aquaculture is essential. Identifying medicinal plants is a fundamental step toward sustainable development. Anvillea garcinii is a perennial shrub from the Asteraceae family, native to southern and southeastern Iran, with traditional uses for wound healing, dysentery, and liver disorders. Its aerial parts contain phenolics, flavonoids, and sesquiterpene lactones, which exhibit anti-diabetic, anti-inflammatory, hepatoprotective, anti-HIV, antifungal, and antioxidant properties. Essential oil analysis has revealed bornyl acetate (33.7%), cis-nerolidol (7.3%), and camphene (6.1%) as major compounds. Despite extensive global research on its phytochemistry, Iranian ecotypes remain understudied. Therefore, this study aims to compare the phytochemical and morphological traits of A. garcinii across two natural habitats in Darab, Fars province. The results will provide baseline data for domestication and pharmaceutical exploitation. Materials and Methods: This study investigated two natural habitats (Dolatabad and Cement Factory) of the medicinal plant Anvillea garcinii subsp. radiata in Darab County, Iran. Geographic coordinates and altitude were recorded using a GPS device. Along four 100-m transects, 40 plots (2 × 1 m) were established to measure morphological traits, including canopy cover, plant height, inflorescence length, and number of flowering branches. Soil physicochemical properties (pH, EC, texture, organic matter, calcium carbonate, and CEC) were also analyzed. Chlorophyll fluorescence parameters (Fo, Fm, Fv, Fv/Fm, Tm, and Fv/F₀) were measured using a fluorimeter. Elemental analysis (Fe, Mn, Cu, and Zn) of plant samples was performed by atomic absorption spectrometry after dry ashing. Phytochemical analysis involved methanolic extraction via a Soxhlet apparatus. The extracts were analyzed using GC-FID and GC-MS with an HP-5MS column to identify chemical constituents. Compounds were characterized based on retention indices and mass spectral comparison with NIST libraries. These comprehensive analyses provide baseline data for domestication and pharmaceutical exploitation of this medicinal plant in Iran's rangelands. Results and Discussion: Phytochemical analysis of Anvillea garcinii from two habitats in Darab (Dolatabad and Cement Factory) revealed 31 distinct compounds. In Dolatabad, the major compounds included 3-Oxatricyclo[4.2.0.0²⁴]octan-7-one (29.52%), 4-Nonenenitrile (9.009%), and 2-Ethyl-3-methyl-4,6-diphenylpyridine (7.85%). In the Cement Factory habitat, the dominant compounds were Octadecenoic acid (Z)- (17.30%) and Hexadecanoic acid methyl ester (8.73%). Morphological analysis showed an average plant cover of 33.10%, a density of 5 bases per unit, a mean height of 28 cm, a crown diameter of 54.50 cm, an inflorescence length of 19.70 cm, and 25 flowering branches. Elemental analysis indicated elevated levels of manganese (632 mg/kg), copper (56 mg/kg), and nickel (95 mg/kg) near the cement factory, suggesting industrial impact and potential phytoremediation capability. Photosynthetic traits showed significant stress-induced differences: Dolatabad exhibited a normal Fv/Fm (0.66) but a very low performance index (PI = 0.01), while the Cement Factory showed a damaged photosystem II (Fv/Fm = 0.34) but higher PI (0.38) and electron sink capacity (Area = 330,655), indicating compensatory mechanisms. Overall, habitat conditions strongly influence phytochemical diversity, fatty acid versus terpenoid profiles, and physiological responses. Dolatabad samples showed superior pharmaceutical potential, with higher diversity (35 compounds) and bioactive terpenes, while Cement Factory samples accumulated more fatty acids as stress responses. The unique compound 3-Oxatricyclo[4.2.0.0²⁴]octan-7-one, a strained bicyclic ketone, shows promise as a synthetic intermediate for pharmaceuticals and materials science. Other identified compounds, such as 4-Nonenenitrile (industrial applications), Z,E-2,13-Octadecadien-1-ol (pheromone/bio-pesticide), and oleic acid derivatives (antimicrobial, antioxidant, and insecticidal activities), highlight the species' diverse biotechnological potential. These findings confirm ecological chemotype plasticity and emphasize the importance of habitat selection for medicinal applications Conclusion and Suggestions: This study, as the first comprehensive phytochemical investigation of the medicinal plant Anvillea garcinii in natural habitats of Iran, represents a fundamental step toward understanding the hidden potential of genetic resources in the country's rangelands. The findings clearly demonstrated that the studied habitats in Darab County, despite plausible environmental stresses (particularly in the cement factory area, evident from photosynthetic indicators), serve as a rich reservoir of secondary metabolites with medicinal and industrial value. The identification of 31 chemical compounds, including predominant and rare compounds such as 3-oxatricyclo[4.2.0.0²,⁴]octan-7-one (29.52%), 4-nonenonitrile (9.00%), and 9-octadecenoic acid (17.30%), not only confirms the chemical richness of this plant but also reveals its potential applications in drug synthesis, biopesticides (pheromones), and the cosmetic-hygiene industry. The qualitative and quantitative differences in essential oil composition between the two studied habitats indicate the significant role of ecological and environmental factors on the chemical composition of the plant. Phytochemical data showed a significant correlation with soil properties, such that nutritional elements and physical parameters of the soil effectively influenced the content of major compounds. These results emphasize that careful habitat selection and intelligent site planning for cultivation and harvesting can be an effective strategy for optimizing the quantity and quality of active compounds in medicinal plants. Anvillea garcinii, by demonstrating remarkable metabolic flexibility in response to environmental stresses, represents an outstanding example of biochemical adaptation in plants of arid and semi-arid regions. This plant possesses high potential for producing valuable medicinal and industrial compounds. However, ecological and environmental variations can significantly impact the chemical content of this plant. Therefore, special attention must be paid to habitat conditions and environmental factors when planning for the cultivation and industrial exploitation of this species.