Irrigation
Hajar Norozzadeh; Mahsa Hasanpour Kashani; Ali Rasoulzadeh
Abstract
Climatic changes and human activities are among the important factors that affect the flow of rivers and it is very important to determine the contribution of these factors in order to better manage water resources. In recent years, there have been major changes in the watersheds, and the amount of runoff ...
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Climatic changes and human activities are among the important factors that affect the flow of rivers and it is very important to determine the contribution of these factors in order to better manage water resources. In recent years, there have been major changes in the watersheds, and the amount of runoff and river flow has decreased, or in some cases, the flow has increased due to the occurrence of floods. The issue of reducing the amount of runoff, especially in the arid and semi-arid regions of Iran, is one of the basic challenges related to the management of water resources. Hydrological changes primarily result from a combination of natural or climatic factors, including precipitation levels, air temperature, and overall warming of the Earth. Additionally, human activities, such as the construction of dams, creation of reservoirs, urbanization expansion, and indiscriminate harvesting, play a significant role. It is important to note that these factors are interconnected, and alterations in one can impact the others. The increase of greenhouse gases and climate change has caused a change in the hydrological cycle and the amount of runoff in the watersheds and has increased the number of climatic extreme events. The main purpose of this study is to determine the contribution of each of these factors on the discharge changes of the Gharehsoo River, one of the most important rivers of Ardabil province, using elasticity-based methods (non-parametric and Bodiko-based methods).
Materials and Methods
In this research, firstly, in order to determine the point of change in the amount of river runoff and to divide the base and change period, Petit's test was used during the statistical period of 1984-2019. This test was done using Xlstat software. According to the results of this test, there was a change in the annual flow time series in 1997, which was considered as the base period from 1984 to 1997 and from 1998 to 2019 as the period of changes. Then, the contribution of each of these factors was determined using elasticity-based methods.
Results and Discussion
In the elasticity-oriented method, the non-parametric method and the methods based on Bodiko's assumptions were used to calculate the elasticity coefficient.The results showed that in Samyan station, in the non-parametric method, the contribution of human activities is 88.26% and the contribution of climate change is 11.74%. The contribution of human activities and the contribution of climate change for the methods of Schreiber, Aldekap, Bodiko, Peek and Zhang, respectively 91.98 and 8.02, 90.02 and 9.97, 91.98 and 8.02, 90.80 and 9.20, 92.37 and 7.62 are estimated. In general, in the elasticity method, the contribution of human activities is 88.26 to 92.37 percent and the contribution of climate change is from 7.63 to 11.74 percent, depending on the non-parametric and Bodiko method. At the Dost-Beiglo station, employing the non-parametric method reveals that human activities account for 96.13% of the observed changes, while the remaining 3.87% is attributed to climate change. The contribution of human activities and the contribution of climate change for the methods of Schreiber, Eldekap, Bodiko, Pick and Zhang are 97.71 and 2.29, 97.42 and 2.58, 97.56 and 2.44, 97.48 and 2.52, 97.71 and 2.29 are estimated. In general, in the elasticity-oriented method, the contribution of human activities between 96.13 and 97.71 percent and the contribution of climate change from 2.29 to 3.87 percent, depending on the non-parametric and Boudico-oriented method, have been met.
Conclusion
In this research, different hydrometeorological data such as precipitation, evaporation and transpiration and monthly discharge from the Samyan and Dost Beiglo stations were used for the statistical period of 1982-2019. First, by using Pettitt's test, it was determined that the river flow rate has changed abruptly since 2016. Therefore, the entire statistical period was divided into two natural and change periods, and then, using elasticity-based methods, the contribution of human activities and the contribution of climate change were determined. According to the results obtained in both stations, the impact of human activities (more than 88%) on the basin's runoff is far more than climate change (less than 11%). Therefore, it seems necessary to prevent the effective human activities on reducing the river flow in solving and managing water problems in the basin.
Soil science
Reyhaneh Kashtabeh; M. Akbari; Ava Heidari; Aliasghar Najafpour
Abstract
IntroductionOne of the most fundamental global environmental challenges in the past two decades has been the issue of soil pollution and degradation. Soil, as an important environmental element, has played a significant role in food production, human health, and living organisms, but various factors, ...
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IntroductionOne of the most fundamental global environmental challenges in the past two decades has been the issue of soil pollution and degradation. Soil, as an important environmental element, has played a significant role in food production, human health, and living organisms, but various factors, by both human and naturally have destroyed it. The exploitation of natural resources with activities such as mining and quarrying, as an anthropogenic action (caused by human activities), is one of the most important factors of human intervention in nature and also one of the environmental hazards of soil degradation, which has caused the spread of desertification. Sangan iron mines in Khaf city are the largest mines in the northeast of Iran. According to the geomorphological disturbances caused by the activity of Khaf iron ore mines and the geological composition of the region, there is a potential for causing pollution and destroying the soil around the mine. This research was conducted with the aim of evaluating the impact of mining activity on concentration of some heavy metals such as lead, iron, nickel, copper, and arsenic in the soil around the iron ore mine in Sangan area of Khaf city in Khorasan Razavi province. Realizing the polluted hotspots due to the concentration of heavy metals, as one of the important signs of soil pollution and the spread of desertification, is one of the goals of this research, and the results can be effective in making appropriate management decisions to prevent soil pollution and further destruction.Materials and MethodsIn order to conduct this research, 60 soil samples were systematically taken from a depth of 0-20 cm from two areas adjacent to the mine and control. The concentration of aqua regia extracted heavy metals was measured using an inductively coupled plasma-optical emission spectroscopy (ICP-OES). In the first stage, the results were descriptive, and in the second part, after performing tests related to the normality of the data, they were inferential using the parametric independent t-test and Pearson's correlation coefficient in the statistical environment of the SPSS software. In order to quantify the level of soil contamination with heavy metals, geochemical indices including contamination factor, pollution load index, and enrichment factor were used. The pollution load zoning map of the area adjacent to the mine as well as the average enrichment map of lead and arsenic elements were prepared using the inverse distance weighting interpolation method in the ArcGIS environment.Results and DiscussionThe results of this research showed that the average concentrations of arsenic, copper, nickel, lead, and iron elements in the area near the mine were 12.71, 25.54, 34.59, 48.64, and 38860 mg/kg and in the control area were 8.57, 15.97, 32.13, 16.96, 29110 mg/kg, respectively. The comparison of the coefficient of variation (dispersion criterion) of heavy metals showed that the highest coefficient of variation among the metals is related to the lead with a value of 42.8%, as well as the coefficient of variation for other metals in the area adjacent to the mine also has a relatively high dispersion compared to the control area. In addition, it was found in all elements except for nickel (p<0.05), which indicates a significant difference in the average concentrations between the control area and the area adjacent to the mine. The correlation between lead element and nickel, copper and arsenic variables was inverse and there was a positive and very strong correlation between iron and copper and nickel with values of 0.8 and 0.76 respectively and nickel and copper with values of 0.82. The pollution coefficient of the lead elements in the area adjacent to the mine showed moderate to significant pollution levels, which is more polluted than other elements. The pollution load in the area near the mine showed that the value of this index was greater than one in the samples closer to the mining areas, which indicates the high contamination of the surface soil with these elements. Lead and arsenic elements in the area adjacent to the mine showed moderate to relatively intense enrichment. From the examination of all the pollution indicators used in this research, as well as the positive and very strong correlation between copper and nickel, the presence of these two elements in the soil of the study area showed no pollution. The comparison of the results obtained from the analysis of soil samples in the two areas of the control and adjacent to the mine showed an increase in the concentration of heavy metals (iron, lead, and arsenic, copper) in the area adjacent to the mining.ConclusionThe results obtained from the analysis of soil samples and pollution indicators in the two control areas adjacent to the Sangan iron ore mine in Khaf city showed that the presence of iron ore industrial and mining sites in the study area and the spread of its wastes and tailings by seasonal and local winds, as well as the activities of humanity and the spread of these pollutants to other areas, can be one of the main reasons for the increase in the concentration of metal pollutants in the soils of this region.
