numerical modeling

The purpose of this study is to determine the contribution of the maximum dust production capacity of 4 centers in the maximum dust production of Khuzestan province. According to the field information on soil texture and land use, the WRF-CHEM chemical model was used to simulate the occurrence of severe dust storms. To simulate the occurrence of a dust storm and estimate the maximum power of dust production at the peak of the activity of the dust system of four hypothetical centers in Khuzestan province, in addition to the dust concentration data of the environmental organization, in the verification of the event and the selection of the system from the data meteorological organization; Wind direction and speed and horizontal field of view were used. First, the simulation was done in real mode with full physics of the model, and in the next step, the amount of dust production and the role of each dust center in the centers were checked with the assumption of moistening of the surface layer of soil and ground. Among the 94 dust systems by defining the maximum event conditions, 39 main systems were selected. The results showed that each of the foci, on average and independently, caused an increase in dust and feeding systems that migrated to the region during the storms that occurred over two decades (2003-2018). The maximum contribution of each center was determined separately and simultaneously at the peak of the activity of the dusting systems. The results showed that at the peak of the activity of the dust collection systems, the maximum production capacity of source 1 (Horal Azim and North Khorramshahr) is 65.14% on average, source 2 (Mahshahr Center, Omidieh and Hindijan) is 59.91%, source 3 (East Ahvaz city) was 52.27% and source 4 (southeast of Ahvaz) was 55.74%. The total share of the average dust production in the four centers of the province is 62.94%, which if it is deducted from the amount of dust produced in the southern region of Khuzestan, which is 83.30% of the total dust in Khuzestan during the occurrence of different systems. , the remaining 20.36 percent, which is the share of unknown sources such as secondary sources that have the potential to produce dust or the dust created from them is the result of the discharge of major and larger sources. Knowledge of the contribution of each of the numerous dust centers in the Khuzestan Plain can help the decision-makers of operational plans to control internal fine dust centers.

In this study, we have tried to investigate the interaction between groundwater resources of the Urmia domain and Urmia Lake through numerical modeling. The conceptual model of the Urmia aquifer has been prepared using available information and results of geophysical studies. Modeling of flow and soluble transport in the coastal part of Urmia aquifer has been done using the GMS software package. In this case, groundwater flow is first modeled using the MODFLOW module and then the solute transport (in this study, chloride concentration) is performed using the MT3DMS code. After modeling the flow and soluble transport, the outputs are used in the SEAWAT code. The calibration of aquifer hydraulic parameters was performed using the PEST code and manual method. In running the model in unsteady state and using calibrated parameters, the values of ME, MAE and RMSE of the model reached 0.11, 1.14 and 1.41, respectively. The results of flow modeling, solute transport, and mixing of saline and freshwater in the Urmia aquifer show that in the present situation, the relationship between the Urmia aquifer and Urmia Lake is as low as possible and the salinity of the aquifer is very low. Besides, the analysis of the water resources behavior in the coastal parts of this aquifer in two scenarios, including the 50% reduction in discharge of four main rivers and the 50% increase in groundwater extraction, shows that no significant change was made in the results of this model. Since solute transport is a function of flow dynamics in the region, a one-way flow of groundwater towards Urmia Lake, low permeability sediments (due to particle size and formation of salt layers) prevents the invasion of the Urmia Lake saltwater into the aquifer environment.

Dust storms are one of the environmental problems that affect human health, air quality and the economies of the countries of the world on a large scale. The purpose of this study is the identification of the source of dust entering the east of Iran and tracking its route. Initially, using horizontal visibility data, satellite imagery, Dust Aerosol Index related to the OMPS, and AOD, the dust storms detected from 2000 until 2018 were examined. Then, the pressure data, wind direction, wind speed, geopotential heights and jet streams at various atmospheric levels were obtained from the European Meteorological Center (ECMWF) with a spatial resolution of 0.25 * 0.25. Finally, the HYSPLTE model was used to determine the origin of the storm formation. The results showed that 46.67% of the region's dust storms were local, 33.33% were transmitted, and 20% occurred concurrently. The satellite studies of the transmitted dust storms showed that they formed in southern Iraq and central Saudi Arabia and then moved to the studied area, which was compared with the results of the model. Synoptic studies also showed the synoptic origin of the storms and their being structured by northern winds, where jet streams and polar jet streams converge to provide favorable conditions for dust storms. The study of the storms formed at the site indicated that severe storms in the area could be due to the pressure gradient, cyclones and jet stream interference in the area.

The purpose of this study was to investigate and identify the effect of blocking systems on Iran's poisoning during the period 1975-2015 using the Blocking numerical index. The results showed that in the cold seasons most of the blockades affecting the atmosphere of Iran were in the northern Atlas. Also, the study of the severity of effective blockades affecting Iran's climate showed that the strong blocking is moderate in terms of the highest number after the blocking, indicating that Iran was more affected by moderate blocking (74.6%) and then strong (21.1%). The number of weak blocking is very low (4.3%). Due to the frequency of occurrence of blocking also was found wet Iran in months. Cold, the core of the blocking in between longitude 30 ° west and 30 ° East over the Atlantic formed and as the warm season approaching, the core the land was transferred to the regions dominated by positive changes in parameters affect precipitation. Also, in Bandal's review in different seasons, it was revealed that in winter, with the retreat of the adjacent high pressure and the strength of the polar vertex, along with the occurrence of strong and long blockades, the average rainfall is more than the other seasons.

Nowadays for many reasons, including geological structures governing on the project site, the foundation near of the rock slope and embankment are constructed. The analysis of this type foundation, the slope effect on found is non-negligible and will be cause changes on failure system. Generally, conditions governing on slope (such as position, body masses, physical and mechanical properties, strength parameters and etc.) and the the foundation conditions (foundation type, material, spacing of the slope, the weight on the foundation, found deviation, Angularity of foundation and etc.) play an important role in the foundation stability analysis. In this study, we attempted to numerical modeling of Phase 8 Gas flare foundation of South Pars Gas Complex is located near slope by the finite difference method (FDM) using Flac2D software. The aim of this study, evaluating and analyzing the probabile failure mechanism. Finally, Gas flare stability based on the results of the modeling is controlled.