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"Ahmadi, Azadeh"
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Assessment of CMIP6 models and multi-model averaging for temperature and precipitation over Iran
In this study, the performances of 40 Coupled Model Intercomparison Project Phase 6 are evaluated against observational data at synoptic stations in Iran using various evaluation criteria. The results reveal diverse model accuracy across different climate conditions and criteria, emphasizing particularly notable disparities in the nonstationarity R criterion compared to others. Although according to the ranking of the raw and bias-corrected outputs of CMIP6 GCMs for Iran, the NorESM2-MM, AWI-ESM-1-1-LR, and MPI-ESM1-2-LR models are consistently among the top six ranked models for precipitation in both raw and corrected outputs. For temperature, MPI-ESM1-2-LR, TaiESM1, INM-CM4-8, and IITM-ESM are consistently among the top six models for both the raw and bias-corrected outputs of CMIP6 GCMs. The Bias correction methods, including quantile mapping and linear scaling, integrated with Bayesian model averaging, were applied. While quantile mapping demonstrates superior performance and less disparity than linear scaling, it proves ineffective for correcting biases at stations with bias nonstationarity over time. The RMSE for monthly precipitation ranges from almost 0 to 200 mm, with a large RMSE value related to the high precipitation stations, and the monthly temperature exhibits a range of 0 to 4 °C. The use of a multi-model ensemble improves accuracy compared to individual models, resulting in a reduction in the differences between the minimum and maximum RMSE values from 178.6 to 91.0. Additionally, the range for mean absolute error decreases from 126.9 to 93.3, and the difference in the correlation coefficient narrows from 0.9 to 0.42. Averaging models after bias correction prevents significant fluctuations while maintaining higher accuracy, in contrast to the second method, which involves bias-correcting models after averaging.
Journal Article
The future of extreme climate in Iran
Iran is experiencing unprecedented climate-related problems such as drying of lakes and rivers, dust storms, record-breaking temperatures, droughts, and floods. Here, we use the ensemble of five high-resolution climate models to project maximum and minimum temperatures and rainfall distribution, calculate occurrences of extreme temperatures (temperatures above and below the historical 95th and 5th percentiles, respectively), analyze compound of precipitation and temperature extremes, and determine flooding frequencies across the country. We found that compared to the period of 1980–2004, in the period of 2025–2049, Iran is likely to experience more extended periods of extreme maximum temperatures in the southern part of the country, more extended periods of dry (for ≥120 days: precipitation <2 mm, Tmax ≥30 °C) as well as wet (for ≤3 days: total precipitation ≥110 mm) conditions, and higher frequency of floods. Overall, the combination of these results projects a climate of extended dry periods interrupted by intermittent heavy rainfalls, which is a recipe for increasing the chances of floods. Without thoughtful adaptability measures, some parts of the country may face limited habitability in the future.
Journal Article
Effect of phycocyanin and phycoerythrin on antioxidant and antimicrobial activity of refrigerated low-fat yogurt and cream cheese
Cyanobacterial phycobiliproteins, such as phycoerythrin (PE) and phycocyanin (PC), are colored potential bioactive proteins that have antioxidant and antimicrobial properties. In this study, we formulated a new food prototype based on PE and PC-fortified low-fat yogurt and cream cheese. Four distinct low-fat yogurt and cream cheese products were manufactured, including a control group (No PE and PC), samples produced with phycoerythrin (+ PE), samples produced with phycocyanin (+ PC), and samples produced with both phycoerythrin and phycocyanin (PC + PE). Afterwards statistically compared the physicochemical composition, colorimetric properties, antioxidant and antimicrobial activities, and sensory profile of the fortified foods at 4 °C and 8 °C for 28 and 42 days. Additionally, we confirmed that PE and PC are not toxic to
Caenorhabditis elegans
at concentrations up to 1 mg/mL. The results showed that the MIC of PE and PC against
E. coli
was significantly higher than against
S. aureus
(3.12 ± 0.05 µg/mL vs. 1.56 ± 0.01 µg/mL, respectively;
p
≤ 0.05). Additionally, the maximum diameter of the inhibition zone of PE and PC against
S. aureus
was significantly higher than against
E. coli
(6.6 ± 0.011 mm vs. 11.66 ± 0.02 mm, respectively;
p
≤ 0.05). Results of color parameters showed that the control group had significantly higher L* values than the samples enriched with PE and PC. Moreover PE and PC significantly increased the a* and b* values respectively. The amount of ΔE in the control yogurts and cream cheese was higher than in the samples with PE and PC. Overall, the results showed that adding PE and PC had a significant effect on all measured factors (
p
< 0.01). Cream cheeses and low-fat yogurts enriched with either PE or PE + PC had the greatest antioxidant activity and the lowest number of psychrophilic bacteria and mold, and yeast counts at the end of the test period. Therefore, low-fat yogurt and cream cheese containing cyanobacterial PE and PC can be considered an innovative dairy product for the food industry. This study marks the initial effort to employ PE and PC derived from
Nostoc
sp. and
Spirulina
sp. as antioxidant and antimicrobial agents in the food industry.
Journal Article
Future runoff assessment under climate change and land-cover alteration scenarios: a case study of the Zayandeh-Roud dam upstream watershed
In this study, hydrological responses to climate change and land-cover alteration on future runoff in the Zayandeh-Roud dam upstream watershed were assessed. In this regard, land-use maps in 1996, 2008, 2018, and 2033 were generated using Landsat time-series (TM and OLI), Support-Vector Machine (SVM), and the CA-Markov chain model, for analysing the effects of land-cover alteration on future runoff. Second, the Global Circulation Model (GCM) scenario time-series under RCP 2.6 and RCP 8.5 scenarios were downscaled to evaluate the impacts of climate change on future streamflow. Eventually, the HEC-HMS model was calibrated (1996–2018) for evaluating the impacts of climate and land-use map changes. Results showed that the percentage of the urban area and farmland in 2033 compared to 2018 were expected to grow by 0.1 and 2.39% upstream of the Eskandari station and 0.05 and 0.71% upstream of the Ghale-Shahrokh station, respectively, although the percentage of the barren area was expected to remain almost unchanged in both regions. The future stream flow of Eskandari and Ghale-Shahrokh stations in 2033 was expected to decrease by 57–63 MCM (for RCP 2.6 and RCP 8.5) and 295–403 MCM, respectively, where 68–72% and 79–86% were expected to decrease under climate change scenarios and remains are due to land-cover alteration.
Journal Article
Water Quality Modeling of Mahabad Dam Watershed–Reservoir System under Climate Change Conditions, Using SWAT and System Dynamics
The total phosphorus (TP) concentration, as the primary limiting eutrophication factor in the Mahabad Dam reservoir in Iran, was studied, considering the combined impacts of climate change, as well as the scenarios on changes in upstream TP loadings and downstream dam water allocations. Downscaled daily projected climate data were obtained from the Beijing Normal University Earth System Model (BNU-ESM) under moderate (RCP4.5) and extreme (RCP8.5) scenarios. These data were used as inputs of a calibrated Soil and Water Assessment Tool (SWAT) model of the watershed in order to determine the effects of climate change on runoff yields in the watershed from 2020 to 2050. The SWAT model was calibrated/validated using the SUFI-2 algorithm in the SWAT Calibration Uncertainties Program (SWAT-CUP). Moreover, to model TP concentration in the reservoir and to investigate the effects of upstream/downstream scenarios, along with forecasted climate-induced changes in streamflow and evaporation rates, the System Dynamics (SD) model was implemented. The scenarios covered a combination of changes in population, agricultural and livestock farming activities, industrialization, water conservation, and pollution control. Relative to the year 2011 in which the water quality data were available, the SD results showed the highest TP concentrations in the reservoir under scenarios in which the inflow to the reservoir had decreased, while the upstream TP loadings and downstream dam water allocations had increased (+29.9%). On the other hand, the lowest TP concentration was observed under scenarios in which upstream TP loadings and dam water allocations had decreased (−18.5%).
Journal Article
Bottom-up capping (BUC) policy under bargaining techniques for inter-sectoral groundwater trading: a case study from Iran
Cap-and-trade (C&T) policy has led to environmental benefits in some groundwater markets by restricting and economically reallocating water permits. However, top-down approaches for capping permits may face resistance from every affected stakeholder. This paper presents an efficient policy framework to improve the implementation of C&T policies in a real shared aquifer in Iran. To this end, groundwater permits for water-selling farms are capped through a bottom-up capping (BUC) policy. A policy analysis that employs static and dynamic bargaining techniques incorporates farms' utilities. Results reveal that the bargaining techniques propose more acceptable capping strategies than the top-down approach. The BUC policy analysis introduces the proposed strategy by dynamic bargaining as the tradable groundwater permits. The effects of irrigation water sales to the industry sector, evaluated using a cooperative game-based optimization model, show that with the fair reallocation of water trading benefits, the current net benefits of agriculture and industry sectors increase by 55 and 27%, respectively. Furthermore, farms reduce their groundwater withdrawals by 35% compared with the current mode. Therefore, the BUC policy for inter-sectoral groundwater trading under dynamic bargaining can lead to the sustainable use of limited groundwater resources by facilitating the capping strategies and improving the water permits productivity.
Journal Article
Acute Kidney Injury Outcome in COVID-19 Patients
Introduction. Despite the high incidence of AKI in patients with COVID-19, the characteristics and consequences of this condition have not been well studied. Methods. This retrospective cohort study investigated the clinical characteristics, treatment methods, and outcome of COVID-19 patients aged 18 years and older who were hospitalized in Imam Hossein Hospital, Tehran, from February 20th, 2020 to June 20th, 2020. Results. Out of the total 367 patients with COVID-19, 104 (28%) patients were diagnosed with AKI at the time of admission or during hospitalization, 86 (23%) and 18 (5%) patients were diagnosed with the AKI on admission (early AKI) and after the first 24 h (late AKI), respectively. Concerning the AKI stages, 20 (19%) and 18 (17%) patients were in stages 2 and 3, and the cause of AKI in 52 (50%) patients was renal. Moreover, out of all patients with AKI, 25 (24%) and 29 (28%) patients had transient (Kidney function improvement within 48 h) and persistent AKI (kidney function improvement between 48 h to 7 days). Furthermore, 32 (31%) patients developed acute kidney damage (AKD) (no improvement in AKI after 7 days). The survival rate of AKI patients was lower in higher stages of AKI, and in cases that the reason for kidney dysfunction was renal or unknown. However, there was no difference in the mortality rate between the early and late AKI. Conclusion. Since about one-third of the patients with AKI eventually develop AKD, it is of great importance to closely monitor all COVID-19 patients, especially the high-risk ones, for the appropriate diagnosis and treatment of AKI.DOI: 10.52547/ijkd.6610
Journal Article
Optimal water allocation of the Zayandeh-Roud Reservoir in Iran based on inflow projection under climate change scenarios
The impact of climate change on water availability has become a significant cause for concern in the Zayandeh-Roud Reservoir in Iran and similar reservoirs in arid regions. This study investigates the climate change impact on water supply and availability in the Zayandeh-Roud River Basin. For better management, the Soil & Water Assessment Tool (SWAT) was used to develop a hydrologic model of the basin. The model was then calibrated and validated for two upstream stations using the Sequential Uncertainty Fitting (SUFI-2) algorithm in the SWAT-CUP software. The impact of climate change was modeled by using data derived from five Inter-Sectoral Impact Model Intercomparison Project general circulation models under four Representative Concentration Pathways (RCPs). For calibration (1991–2008), the Nash–Sutcliffe efficiency (NSE) values of 0.75 and 0.61 at the Ghaleshahrokh and Eskandari stations were obtained, respectively. For validation (2009–2015), the NSE values were 0.80 and 0.82, respectively. The reservoir inflow would probably reduce by 40–50% during the period of 2020–2045 relative to the base period of 1981–2006. To evaluate the reservoir's future performance, a nonlinear optimization model was used to minimize water deficits. The highest annual water deficit would likely be around 847 MCM. The lowest reservoir reliability and the highest vulnerability occurred under the extreme RCP8.5 pathway.
Journal Article