mohammadhasan naderi

‎The graph $ AG ( R ) $ {of} a commutative ring $R$ with identity has an edge linking two unique vertices when the product of the vertices equals {the} zero ideal and its vertices are the nonzero annihilating ideals of $R$‎.‎The annihilating-ideal graph with {respect to} an ideal $ ( I ) $, ‎which is {denoted} by $ AG_I ( R ) $‎, ‎has distinct vertices $ K $ and $ J $ that are adjacent if and only if $ KJ\subseteq I $‎. ‎Its vertices are $ \{K\mid KJ\subseteq I\ \text{for some ideal}\ J \ \text{and}\ K$‎, ‎$J \nsubseteq I‎, ‎K\ \text{is a ideal of}\ R\} $‎. ‎The study of the two graphs $ AG_I ( R ) $ and $ AG(R/I) $ and {extending certain} prior findings are two main objectives of this research‎. ‎This studys {among other things‎, ‎the} findings {of this study reveal}‎‎that $ AG_I ( R ) $ is bipartite if and only if $ AG_I ( R ) $ is triangle-free‎.

Social security has always been one of the important and effective variables in the challenge of internal and regional competitions in the Persian Gulf. After the constitutional revolution in Iran, there was not much result of the establishment of a legal system according to the wishes of the constitutionalists, but in the south of Iran, insecurity and instability in the ports and on the shores of the Persian Gulf disturbed the social life of the inhabitants of that region. An issue that almost followed a fixed and specific pattern and various internal and external components were effective in its occurrence and escalation. In this research, according to the causes and factors of creating social insecurity in the back-border routes of the Persian Gulf, the effective components in the threat and escalation of these conditions will be investigated. Information has been collected in a documentary and library manner and analyzed with a descriptive-analytical approach.

The study of fish habitats is important for us to better understand the impact of reservoir construction on river ecosystems. Hydropeaking hydropower plants are the main source of renewable energy, meeting sub-daily peaks in electricity demand. Dam reservoir that regulates river water to supply different sectors demands such as drinking water municipal, agricultural, and hydropower generation and this ignores the need for water in the river as the first beneficiary. The development of a rational watershed planning and management plan (develop a suitable ecological flow scenarios) is significant for the survival, reproduction, and development of fish. Recently, several classical approaches were used to estimate ecological flow, including hydrologic, hydraulic, and a habitat suitability modeling approach. The hydrological approach determines ecological flow based on historical hydrological data, of which one representative method is the Tennant method. The hydraulic approach determines the ecological flow according to the wetted perimeter of the cross section of the river. Hydrological and hydraulic approaches are favored because of their simplicity and ease of calculation, but both of them lack the biological mechanisms and biological requirements. Fortunately, the habitat suitability modeling approach combines the knowledge of hydraulics and biology to establish the relationship between habitat and hydraulic factors. It has certain advantages in the evaluation of ecological flow and has attracted more and more researchers’ attention. The most classical habitat suitability modeling approach is the instream flow incremental methodology (IFIM) and its physical habitat simulation component (PHABSIM), which includes the suitability of habitat target species to a series of hydraulic factors such as flow velocity and water depth to build a habitat suitability index model. The habitat suitability modeling approach provides the best range of hydraulic factors such as flow for habitat target species, which has certain reference significance for guiding reservoir operation. The Physical Habitat Simulation Model (PHABSIM) is proposed to simulate the relationship between streamflow and physical habitat for various life stages of target fish species, and thus to determine the optimal ecological flow of the representative river reach.The classical PHABSIM includes two components, namely hydraulic simulation and habitat modeling. On the basis of that, one-dimension hydraulic simulation model is proposed to determine characteristics of the stream in terms of depth and velocity as a function of discharge. As for habitat modelling, the river sectors and aquatic species most vulnerable to the variation of streamflow should be identified initially. Then, the Habitat Suitability Index (HSI) is introduced to reflect the preferences of target fish species with regards to the flow velocity, depth, and channel properties. Basically, HSI was determined according to the number of fish population appearing at the target point. The maximum value of HSI is set at 1.0, and the rest of the HSI values are determined in terms of relative ratio to the maximum value. Then, the Weighted Usable Areas (WUA) is employed to reflect the amount of physical habitat that available for fish species at different flow condition, which can be calculated as an aggregate of the product of a composite HSI. In terms of ecological constraint, maintaining at least 75% of largest WUA is set as an example in optimization modelling, to describe the detailed process to incorporate the ecological demand into reservoirs operation under one certain recovery level.Based on the results, the environmental flow in the range of 2.5-18.55 m3/s was calculated as the amount of release flow needed to stabilize the fish species and habitat of Jajrood River. Also, the low flow months (July to November) compared to the high flow months (March to June), need to consider a higher proportion of the average monthly flow than the mean annual flow as the minimum required environmental flow. The reservoir operation makes flow series flat and the duration of a single pulse increases compared with flow series before construction. Overall, it is obvious that the hydrological parameters of natural flow have a lager alteration due to the construction and operation of reservoir, which may change the downstream riverine structure and threaten freshwater biodiversity. The combination of eco-flow indicators and hydrological regime alteration, which is capable of mirroring the key hydrological information and related ecological connotation, is prove to be an effective method to evaluate the eco-hydrological regimes. It was demonstrated that the operation of the hydroelectric power plant in the hydropeaking system is the cause of a large flow alteration in respect of the frequency and duration of low- and high-flow pulses and the rate and frequency of change in the flow. The change in the manner of operation of the hydroelectric power plant affected the reduction in the degree of transformation of most features of the flow. Trend of maximum and mean flow ratio and maximum and minimum flow ratio has attenuated in reservoir after condition.

‎Let $R$ be a commutative ring with nonzero identity‎. ‎Throughout this paper we explore some properties of two certain subgraphs of the maximal graph of $R$‎.

River restoration and protection of the natural and ecological life of the river in besides to using it for various purposes is one of the most prominent areas of applied water resources science. Environmental flow provision is recognized as a prominent tool to reduce the negative effects of regulation river flow and conservation, restoration, and improvement of natural river habitat quality in watershed management and integrated water resources management. In this study, in order to evaluate and estimate the environmental flow regime of Kordan River, the Flow Duration Curve method based on hydrological statistics of the hydrometric station during the 35-year statistical period (1985-2020) and MesoHABSIM hydromorphocological model based on field studies and observations were used and accordingly, the available habitat suitability of the target fish species in different scenarios of the flow regime was examined. The results showed that the distribution of the minimum amount of ecological flow during the year is relatively uniform and within the river basin flow range (maximum of 1.8 m3/s in April and minimum of 0.3 m3/s in October). However, the optimal ecological flow distribution to provide optimal hydromorphological habitats throughout the year is unequal. Also, the maximum required amount of optimal ecological flow in May is equal to 3.6 m3/s, and the minimum amount of optimal ecological flow in October is equal to 0.7 m3/s. On the other hand, according to the analysis, at most times of the year, flow less than the average annual flow in the studied river which is equal to 3.95 m3/s, while these flows are insufficient to meet the ecological needs of aquatic. The results of the present study show that changes in the hydromorphology of Kordan River due to long-term regulation of river flow, lead to changes in the distribution of optimal morphological habitats. It is noteworthy that the MesoHABSIM model simulates the desirability and availability of fish species habitats for different scenarios of flow regime and river morphology and can also be used in river ecological restoration projects and environmental flow determination.

Investigation of ecological, hydrological status and habitat Suitability of river is one of the key elements in river ecosystem management. In this regard, in the present study, in order to evaluate the ecological sustainable conditions in Zarrin-Gol River of Golestan Province, during stepwise calculations, echo-hydraulic and hydromorphocological analysis of the habitat of Capoeta gracilis (Keyserling, 1861) and ecological flow were studied estimation using hydrological and flow methods (Tennant and Aquatic base Flow) during the 10-year statistical period (2009-2019), hydraulic method (wetted perimeter) and habitat simulation model in different seasons of 2017 and 2018. For this purpose, physical simulation of habitat based on habitat suitability criteria curves was performed by field studies and sampling of hydraulic (depth, velocity and bed index) and ecological (aquatic communities) parameters. First, the geometry of the river model and cross sections were created using the topographic map of Zarrin-Gol River and ARC-GIS software. Then hydraulic simulation of river was performed with HEC-RAS software. In the next step, hydraulic and habitat simulations were performed in PHABSIM model. In this ecological-hydraulic model, the relationship between hydraulic flow and habitat needs of the target species was established using the Weighted Usable Area and the flow- suitability curve of the target species was extracted in different discharges in both adult and juvenile tow age group and new method of classifying the ecological flow regime was considered according to the indices of habitat suitability (water depth, flow velocity and bed). By elicitation of flow-habitat suitability curve, suitability river in terms of quantity and location was investigated. Based on the results, the optimal ecological flow regime to provide the ecological potential of habitat of index species is different by combining different methods for the studied periods during the year and accordingly, to maintain optimal conditions and protect the ecosystem and habitat components of biological communities, The required flow between 1.43 (in July-February) to 3.76 m3/s (in April), with an mean annual bio-flow of 1.74 m3/s (equivalent to 74.3% of  natural stream of the river) should be inside of Zarrin-Gol River. Also, the susceptibility of the Capoeta gracilis species to changes in velocity and bed materials is high and the weighted usable area increases with the depth remaining in optimal conditions. According to the results of this study, the distribution of habitat suitability along the Zarrin-Gol River, under the influence of geometric, hydraulic parameters and flow rate, indicates the favorable habitat conditions of the Capoeta gracilis species in the downstream area and poor conditions in the upstream area.

The field of ecohydraulics is rapidly growing as the society requires a better understanding of the interrelations amongst the dynamics of the physical processes pertaining to aquatic ecosystems and the modifications observed in their habitat as well as the biological responses of the organisms. Environmental flow science is a common tool for assessing the consequences of changing the flow regime of aquatic ecosystems and providing a minimum flow of aquatic species protection. Environmental Flows assessment is a global challenge involving a number of tangible and intangible segments of hydrology, hydraulics, biology, ecology, environment, socio-economics, and several other branches of engineering including water resources management. River impoundment (dams, weirs), water diversions and consequent modifications to flow regimes have highly destructive effects on aquatic species and ecosystems.    

In this research, two most common hydrologic methods Tennant and FDC Shifting were compared with a habitat simulation method i.e. PHABSIM. Tennant method is the most popular hydrological method in rivers and is based on the historic flow data. Investigation of the relationship between hydrologic approaches and physical habitat simulation approach and presentation of new recommendations based on the ecological and hydrological data can be very useful for estimating environmental flow in planning phase of river projects. We used river habitat simulation program to model the depth and velocities around boulder clusters to evaluate the habitat for Capoeta habitat in Zarrin-Gol River. The Zarrin-Gol River is one of the rivers in Golestan province in northern Iran. The statistics required for hydrologic calculations were also collected from Zarrin-Gol hydrometry station during the 42-year statistical period (1353-1395). In this regard, after the field studies and the development of the habitat suitability model for the target species, the Habitat simulation of the flow was carried out and eventually the ecological flow regime was extracted. In order to identify the important habitat variables and assess their impact, the life pattern of fish species was divided into juvenile and adult life stages.

Based on ecological assessment, the environmental water requirement of Gharahsoo river is 30% of mean annual flow for spring and summer and 10% of mean annual flow for autumn and winter seasons. It was found that application of Tennant and FDC Shifting methods led to dramatically low discharges as fixed minimum environmental flows, while habitat simulation method gave an acceptable estimation of ecological regime. However, habitat simulation technique assesses the allowable value of extraction from river flow dynamically, considering the ecological condition and average intermediate values. River conditions including flow velocity, water depth and river bed substrate are combined to form unique habitats facilitating the survival and growth of fish species populations.  Habitat forms are observed in a wide range of rivers depending on the diet and the river type such as Pool, Riffle and Run. The destruction of the Riffle substrate causes disruption and impacts the biological integrity of the current. According to the Q-WUA curve of the Riffle habitat in high waters and flood conditions, the area available for juveniles of the target species decreases because of the flood, morphology and habitat of the river, so large and continuous floods inhibit the opportunity to rebuild habitats from the river and endanger the lives of fish. One of the factors limiting the desirability of the habitat and thus reducing the available habitat in low river flows is the low flow velocity, as well as high stream flow flows. The maximum and minimum flow regime, required to maintain the Zarrin-Gol river ecosystem according to ecological needs, was 2.49 and 0.58 m3/s in April and November, respectively, with an average value of 1.25 m3/s (59 % of natural stream of the river). In the next step, habitat suitability distribution along the stream was investigated. This was performed for the full range of discharges. Habitat suitability distribution along the stream at different discharges indicated that the upstream part of the stream had the poorest habitat condition and moving towards the downstream parts, the habitat suitability condition was improved.

Application of the Tennant method based on a hydrological system can be an inappropriate choice for determining the minimum flow to maintain the ecological environment of the river. According to the results, the PHABSIM model can simulate flow, habitat suitability of target species and the habitats dynamics accurately, which is highly required to protect the proper habitat of fish in river ecosystems.

Investigation of water quality variations in rivers is one of the important criteria for determining the health of watershed. Quantitative and qualitative monitoring plays an important role in sustainable management of river ecosystems. In this regard, the present study was carried out to evaluate the water quality of Ziarat River in Golestan Province, after water sampling from six stations along the river from December 2016 to July 2017 using NSFWQI index. Correlation analysis and cluster analysis were also used to find out the relationships between physical and chemical parameters of water. The results were compared with the standard values of the World Health Organization (WHO) and US Environmental Protection Agency (EPA). The results of this study shows higher values of BOD, Na, Ca and PO4 at the downstream station, as compared to the ones in the upstream stations due to reciving wastewater from different sources. Statistical analysis indicates that there is a significant and strong relationship between some physical and chemical parameters of the river. The results showed that the mean concentration of DO, TDS, Cl, Na, Po4 and NO3 are 5.4, 627.5, 110.02, 48.5 and 9.25 mg/l respectively, and the mean value of Electrical Conductivity was 1028 μs/cm. The comparison of NSFWQI values at the six stations of Ziarat River in different seasons indicated that the first station (Tolboneh, Upstream) had the highest value (55) in May, and the sixth station (Downstream) had the lowest value (35) in July. According to this index, the river water quality is medium in the upstream station and bad in the midstream and downstream stations. The results interpretation showed from upstream toward downstream stations, the pollution load increases and the water quality decreases. Therefore, in order to manage the river water quality, the focus should be done on emission control of point source and nonpoint sourec pollusions. The results of this study provide the opportunity for decision on monitoring and controlling pollutant sources and the proper measures for restoration of river ecosystem for effective use in various applications. Finally, according to the results obtained from NSFWQI index, it can be said that the NSFWQI index describes the quality of water resources easily and reliably and its application is usefull for water resources management of other rivers.

In the studies of water resources sustainability and development planning in the watersheds, ecological values and continuance life cycle of the river ecosystems should be recognized. The natural flow regime, plays a key role in protecting river habitat components and biodiversity formation. For this purpose, in the present study, with step-by-step measuring and calculating the environmental flow of the Zarin_Gol River in Golestan province and using hydrological methods of Tennant, Tessman, Texas and Ecodeficit , the sustainable ecological conditions were studied and target fish habitat analysis with Ecohydraulic Habitat Physical Simulation Model (PHABSIM) compared. The results showed that by performing hydraulic simulation and analysis of habitat discharge-physics time series using curves Suitability Index, range of flow regime required to provide habitat ecological potential Paracobitis hicanica was between 0.85 to 4.42 m3/s, with Mean Annual Flow of 1.73 m3/s (equivalent 80 percent of natural stream of the river), It should have existed in inside the Zarin_Gol River. The flexibility and effectivenessof the flow regime of the hydrological methods of Tannant, Texas and Tessman were not sufficient for the conservation and restoration of the studied river habitat. But Ecodeficit method, by providing environmentally friendly flow statistics, while providing in-stream needs, well describes the hydrological changes of the Zarin_Gol River flow regime. According to the results, the ecological optimum flow regime assigned by habitat simulation method is able to protect the natural flow regime for preserving the ecological values of the river, Proper performance of river habitats and preservation of morphological conditions of river bed. The methods used in this study and the obtained results, provide a valuable reference for water resources planning and ecosystem protection in rivers.

Determining environmental flow is one of the most important topics in the integrated management of water resources for managing river health, establishing Sustainable balance in ecological conditions and preserving life of river bound ecosystems. In this regard in this research, environmental flow of the Ghazmahalleh river in Kordkouy city of Golestan Province was calculated and evaluated using hydrological methods to improve the ecological environment, maintaining the natural regime of the flow and protecting the biological diversity of the ecosystem. Statistics required for hydrological calculations used from information of hydrometry station of Ghazmahalleh during 44 year statistical period (1970 to 2016) with mean annual flow of 0.24 m3/s. Results showed that in order to protect and improve the status of the river at the minimum acceptable bioavailability, FDC Shifting method in management class B with a flow of 0.12 m3/s (51 Percent mean annual flow) in this study due to the consideration of biodiversity management classes and the proper adaptation of the pattern changes within the year of environmental flow and the mean annual flow, priority to other methods and is most acceptable method for estimating environmental flow. In this research proved, results of Tennant method provide lower than the minimum environmental requirement and using this method with imposing stress on the hydrological system, is an inappropriate choice for estimating minimum flow Ghazmahalleh river to maintain the ecological environment. Also Tessmann, Arkansas methods and DRM estimated very low or very high flows of mean flow river. Certainly, allocation amount of environmental flows to these methods provides several problems for different stakeholders from river flow.

Ecosystems management of river and water flow necessary for continuity of life and ecological sustainability of river based systems, requires recognition of environmental flows in the politics and intentions of water resource development projects and inclusion it in watershed management programs. In order to, in this research were analysis application of hydrological methods (Tennant, Tessman, Flow Duration Curve, Smakhtin, Arkansas, FDC-Shifting and DRM) and ecohydraulic habitat suitability simulation model (SEFA) in the environmental flows assessment of Qarasoo River in Golestan Province in interval of hydrometry stations Ghazmahalleh and Siahab, respectively with mean annual flow of 0.26 and 1.92 m3/s for restoration habitat, natural resurrection and conservation of biodiversity. The investigating provision of optimal flow ecosystem with field studies and measurements hydraulic and qualitative characteristics of the river in order to identify the favorable conditions of Capoeta capoeta gracilis hierarchical habitat showed would have the maximum and minimum flow regime required to preservation the Qarasoo river ecosystem according to ecological needs in months of april and september is estimated to order equivalent 3.11 and 0.48 m3/s, with average annual 1.6 m3/s (equivalent 83 percent of natural stream of the river). The results of study show environmental menaces will follow using the values obtained from simple hydrological methods Tennant, Smakhtin and Flow Duration Curve in water resource planning of this river , by contrast ecohydraulic model of SEFA can provide a general croquis of habitat suitability in intervals different of river relative to regime changes natural flow and attainment to optimal

changing the flow regime of aquatic ecosystems and providing a minimum flow of protection aquatic species. The purpose of this research is to provide the essentials to be prepared tools for the assessment and design of restoration and regeneration projects for Zarrin-Gol river habitats using ecohydraulic and hydromorphological indices based on the habitat suitability simulation. In this regard based on the research framework, after the field studies and the development of the habitat suitability model for the target species, the hydrodynamic simulation of the flow was carried out and eventually the ecological flow regime was extracted. The results showed that River2D model by connecting the flow requirement characteristics of C.Capoeta gracilis and using hydraulic and hydrological relations, would have the maximum and minimum flow regime required to maintain the Zarrin-Gol river ecosystem according to ecological needs in the months of april and october is estimated to order equivalent to 5.09 and 0.89 m3/s, with average 1.79 m3/s (equivalent 84 percent of natural stream of the river). Based on the results of this study, in environmental studies of water resources and river engineering, the two-dimensional hydrodynamic River2D model is able to simulate flow, modeling habitat suitability of target species and predict the dynamics of habitats to protect the proper habitat of fish in river ecosystems. The calculation of the environmental flow can be an appropriate estimate for the ecological response of the river to the morphological changes caused by hydrological processes.

Water quality river is important from the economic, social and environmental aspects, and its importance is felt in the planning of water resources management and health assessment of watersheds. The present study aimed to investigate the water quality of Qarasoo River in Golestan province by descriptive cross-sectional method using qualitative variables and biological parameters of water in hydrometric stations located on Qarasoo River during the period from 1380 to 1393. An overview of the relationship and sources of physicochemical variables provides. Based on the results of chemical analysis and plotting the Schoeller, Wilcox and Piper diagrams, the water quality of the river is not suitable due to the high concentrations of sulfate, sodium and chlorine ions according to the drug Schoeller diagram, and is agricultural according to the Wilcox In the C3S1 classification, which represents a moderate quality. Also, according to the Piper diagram, which shows the hydrothermal type of water, the qualitative water type is introduced as Calcium-Magnesium-Chloride type. For improving the quality of river water and its efficient, by creating suitable environmental conditions and improving the ecological conditions in the river, point and non-point pollutants entry into the river water especially urban sewage and industrial wastewater and agricultural pollutants should be prevented with long-term plans.

Lack of appropriate allocation Environmental Flow, has been disrupts the vital activities of aquatic organisms, reduces communication between ecosystems, access to suitable areas for spawning and migrating aquatic. In this research, the environmental demand of Gharasoo River at the siahab station hydrometry was investigated at the entrance to the Gorgan Gulf. Were evaluated of In order to obtain the ecological requirement of Gharasoo River in Golestan province hydrological methods of Tenant, Tessman, Arkansas, Physical Habitat Simulation Model (PHABSIM) for species Capoeta capoeta gracilis. The findings of this research show method of Tenant by taking 30 % annual average flow for the spring and summer seasons, 10 % annual average flow for autumn and winter seasons suggests respectively quantities 0/57 and 0/19 cms. Methods of Tessman, Arkansas and Physical Habitat Simulation model Provide estimates environmental water requirement in equal order 0/856, 1/22, 1/63 cms. Also, there was a lot of difference among between the results of estimating the minimum required water requirement for the river using hydrological methods and providing minimum habitat conditions for indicator species using habitat simulation method and as regards the ecological and habitat conditions of the river are a completely dynamic situation.

In this paper we investigate decompositions of submodules in modules over a Proufer domain into intersections of quasi-primary and classical quasi-primary submodules. In particular, existence and uniqueness of quasi-primary decompositions in modules over a Proufer domain of finite character are proved.