نشریه آب و توسعه پایدار
سال دهم شماره 2 (پیاپی 28، تابستان 1402)

The occurrence of natural hazards is always associated with severe damage in the agricultural sector, especially in small-scale farming exploitation units. One of the approaches to deal with these damages is to use the approach of water-energy-food (WEF) nexus in the management decisions of these units. Therefore, the present research was carried out with the aim of analyzing the mechanisms of linking water, energy and food in small-scale farming exploitation units in Hamadan province. The statistical sample of the research was 300 active farmers in small-scale farming exploitation units (below 10 hectares) which were determined by the rule of Cochran formula and sampling was done by cluster method. The main research tool was a researcher-made questionnaire, the content validity of which was confirmed by a panel of agricultural experts and faculty members of the Department of Agricultural Development and Management at the University of Tehran. In addition, the reliability of research’s tool was confirmed through internal consistency procedure calculating Cronbach's alpha and CR (Cumulative Reliability) coefficients (Both above 0.7). Data analysis was carried out using SPSSwin25 and SMART PLS 3 software. The results showed that the overall nexus of water-energy and food from the six dual mechanisms of WEF the Energy or Food has received a more significant effect. According to the findings of the research, in order to strengthen the nexus approach of these vital resources, measures such as providing and introducing coherent and multilateral investment packages; providing training to farmers regarding synergy and unbreakable link of three sources in farm management and paying attention to this approach at different levels of the management system, from policy making and planning are suggested for field-level farm management decisions..

Global warming in recent decades has caused significant changes in precipitation and temperature, including changes in the mean and standard deviation of these variables and changes in the intensity and frequency of climatic extremes (floods and droughts). Given the importance of these changes in water resources management, it is crucial to study the trends in these variables. In this study, in 12 selected stations in different climatic regions in Iran, the changes in monthly and annual precipitation and mean temperature during 1961-1990 and 1991-2020 were examined. The results of Mann-Kendall test showed in most stations precipitation had an increasing trend in the first period, and a decreasing trend in the second period; although in both periods the trend was not significant (Z<1.645). The mean temperature has increased in both periods, which in the second period has increased with a higher level of confidence (Z>2,576) and greater slope than in the first period. The average annual rainfall has decreased in most stations, and the average annual temperature has increased in all stations. The distribution of precipitation and temperature showed that in some stations, the probability of occurrence of extreme events and hot and cold periods in the second period has increased compared to the first period. In some other stations, droughts/floods are more/less likely to occur. This indicates that the activity of air masses affecting each station can be intensified or weakened due to climate change.

Our generation is facing the daunting challenges of climate change and growing pressure on the environment; Challenges caused by human activities. Considering these environmental conditions and their relationship with social and economic challenges, to achieve the United Nations sustainable development goals, comprehensive and strong tools are required to make decisions to identify the solutions supporting sustainable development in the best way. Decisions should have a systematic perspective, and consider the life cycle and all its related impacts. Life cycle assessment (LCA) is a tool possessing these characteristics. In this study, the life cycle assessment method is introduced first and then, several applications of this method in water distribution systems are examined using some articles. The review of previous studies showed that replacing the gravity transfer of water by pumping can reduce greenhouse gas emissions by 64-81%. Also, choosing the right type and diameter for the pipes of the water distribution network - which will reduce leakage from the network - will increase the life of the network and save up to 75% of costs. Finally, recycling the network after its useful life has significant positive environmental effects and can reduce the potential of human poisoning and pollution of natural resources by 60-88%.

The present study was conducted to examine the changes in monthly, seasonal, and annual trends in relative humidity of 13 meteorological stations in the Razavi-Khorasan Province from the beginning of the statistical period of each station until 2021. The study area includes Dargaz, Fariman, Golmakan, Gonabad, Kashmar, Khaf, Neyshabour, Mashhad, Quchan, Sarakhs, Sabzevar, Torbat-e Jam, and Torbat-e Heydarieh counties. Parametric linear regression and the nonparametric Mann-Kendall (MK) test were used to detect trends in relative humidity. The majority of stations have shown decreasing trends at 5% significance level in relative humidity in different time scales, and only in two stations, Quchan (June, December, and autumn season) and Sarakhs (autumn season), the relative humidity showed an increasing trend at 5% significance level. A decrease in monthly mean relative humidity for six stations has been found in the range of 0.7 to 3.5 percent/decade, while an increase for Quchan station 1.9 to 2.6  percent/decade was observed. In addition, most of the studied stations have experienced a decrease in relative humidity on a seasonal and annual scale. A decrease in Seasonal mean relative humidity for six stations has been found in the range of 0.6 to 2 percent/decade, while decreases in annual mean relative humidity stations ranged from 0.9 to 1.6 percent/decade. The results of this research indicate a decreasing trend in the average monthly, annual and seasonal relative humidity during recent years.

According to the base period selected in this research and the average monthly precipitation and temperature, the base period extracted from the statistics of the nearest synoptic station to the study area, the average monthly precipitation and temperature of the future years were simulated by the famous climate model LARS-WG5. Based on the results of this research, it is revealed that from the first of January to the first of March, the average monthly rainfall will increase in the future periods compared to the base period, it will decrease in the month of March and a relative increase in the amount of rainfall will be seen in the rest of the year, that will be more evident in October and November. The decrease of rainfall in the coming months of March due to the beginning of the vegetation period and the water requirement of agricultural plants, Also premature fall of pastures due to drought stress has an effective role in changing hydrological processes and naturally its effect on other environmental components. Regarding the current and future temperature situation, according to the climate change scenarios, the monthly temperature from the HADCM3 model for different months of the year shows the highest temperature changes in the months of March, June, and January, respectively, which indicates the warming of early spring and early summer, as well as It is the beginning of winter in the future periods that these phenomena will have a significant impact on the flowering time of plants, creating water stress in these seasons.

Aquaculture is a sustainable solution to respond to the increasing demand for animal protein and also, food security in the world, and today, in order to develop it, it is necessary to pay attention to the sustainable aquaculture approach (economically, socially and environmentally). The development of modern aquaculture systems has been greatly expanded in recent years and each of them pursues the goals of sustainable aquaculture in some way. In fact, modern aquaculture systems enable the achievement of sustainable aquaculture by maximizing the productivity of resources, reducing costs, appropriate production quantitatively and qualitatively, and a slight environmental effects. Among the systems introduced so far, recirculating aquaculture system, cages, aquaponics, biofloc and integrated multitrophic aquaculture systems are known as promising systems in aquatic production in the world that can be developed in Iran as well. In this review study, in addition to introducing and discussing the importance of these systems in sustainable aquaculture, the resulting opportunities and also, the challenges of developing these systems in the country are addressed

Groundwater is a vital resource that supplies water needs for various purposes. In recent years, with the increase in population growth, the demand for water along with climate change have led to excessive extraction of underground water and the quantitative and qualitative reduction of this valuable resource at the global level. With the increasing understanding of the interdependence of water and development, paying attention to the sustainable management of underground water in shared boundary aquifers to deal with threats such as lack of water, food, energy, loss of ecosystems and biodiversity and most importantly a decrease in human security, is a must-do act. Therefore, in order to achieve an increase in the level of cooperation for the fair and sustainable use of the country's shared boundary aquifers and also to prevent any disputes and conflicts in the future, the successful experiences of international cooperation between shared boundary aquifers such as the Geneva Aquifer Agreement (between France and Switzerland) has been used and suggestions have been made in this regard. The proposed solution includes an initial agreement contract for more cooperation in the field of identifying technical, socio-cultural, political, economic and legal parameters with the participation and activity of all governmental and non-governmental organizations, technical and specialist experts, academic and civil communities as a common set, provision of financial resources to achieve a comprehensive study of the common aquifer status, sharing reliable information in a common base, stablishing an organization agreed by the beneficiary countries and defining the necessary laws and obligations, forming an advisory committee in order to reduce disputes and to monitor the implementation of commitments, and finally, presenting a comprehensive framework in the form of a shared agreement between the beneficiary countries with a common aquifer.

This study, using a qualitative method, seeks to find out what results and consequences the construction of Hasanlu Dam, as a development action on the Lake Urmia catchment area, has from the local people's point of view, and finally Provide a clear definition from the point of view of the local community regarding the effects of this dam on Lake Urmia. Findings of the research show that the construction of Hasanlu Dam as a development action has positive results such as increasing the income of farmers in the region, improving the welfare of local residents and creating dependent employment for some residents, as well as increasing agricultural production. This can be evaluated as a desirable developmental action from this perspective.  The positive attitude of the local community towards this developmental action can be inferred by referring to the concern of local residents to preserve the Hasanlu dam and expand such developmental actions, in exchange for the drying up of Lake Urmia.  However, this development initiative has negative consequences in addition to positive results, the most important of which is the exacerbation of the critical situation of Lake Urmia. In general, it can be said that the construction of numerous dams on the rivers flowing into Lake Urmia is a reckless development that is the main cause of the worsening of Lake Urmia's drought, and it should be replaced with responsible and managed development.

Various factors affect the location of the scour hole formed by the falling flow. Among these factors, we can mention the tailwater depth, the height of the falling flow, the velocity of the flow, the cross-section of the flow and the amount of air entering the flow. In the present study, the location of the formation of scour holes was investigated in the hydraulic laboratory of Tabriz University. Also, the ability of artificial neural networks (ANN) and tree models (M5P tree model) in estimating the location of scour holes downstream of dams was investigated using laboratory data and the results of these two models have been compared with the multivariate nonlinear regression method. The results showed that all three methods, the artificial neural network, the M5 tree model and regression method provide relatively accurate results in predicting the location of scour hole. RMSE value for ANN=1.75, M5=3.75 and Regression=3.89, but due to providing simple linear relationships by the M5 tree model, this method can be used as a practical method to determine the location of scour hole. The analysis of the M5 tree model showed that 4 equations with different linear equations model the pattern of changes in the location of scour hole. In addition, the analysis of the laboratory results showed that the regression equations presented in the present study compared to the common method (using projectile equations) have much less error when predicting the location of scour hole. Also, the laboratory results showed that the head passing through the structure is the most effective parameter in the formation of the scour hole.

The present research was conducted in order to investigate the role of silver nanoparticles (Ag-NPs) in water disinfection in aquaculture systems and also the environmental effects caused by its release in the environment. The literature review showed that very few studies have been recorded about the antiviral effects of silver nanoparticles in aquaculture systems. Meanwhile, silver nanoparticles showed positive effects against many bacterial pathogens such as Aeromonas and Vibrio as well as fungal agents such as Aspergillus and Candida. Since the mentioned microbial strains are among the most important and common pathogenic agents in Iran's breeding systems, the use of silver nanoparticles with the appropriate amount (provided that more than not allowed) can be useful. Examination of various scientific sources showed that the safe and permissible level of silver nanoparticles has been studied in many farmed fish species, including rainbow trout, silver carp, common carp and zebra fish. Considering this issue, breeders can use these substances to control and prevent the spread of infectious diseases in breeding systems, considering the safe and permissible level of silver nanoparticles for each aquatic species. Based on the comparisons, the antimicrobial effects of silver nanoparticles are very high among metal nanoparticles. In general, the release of these substances into aquatic ecosystems can affect the health of many aquatic animals, including fish, and even have negative effects on human health due to the transfer of silver nanoparticles in the food chain.