جستجوی مقالات مرتبط با کلیدواژه « هدایت الکتریکی » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

IntroductionGroundwater is among the most precious natural resources for human health, economic development and environmental diversity. Since the measurement of groundwater parameters and water quality is difficult, costly and far from being available, interpolation techniques are an easy solution. At the same time, there is a strong correlation between groundwater quality and land use in areas with sensitive aquifers. Changes in land use caused by factors such as rapid growth and expansion of urban centers, rapid population growth, and the lack of land, the need for increased production and the evolution of technologies are important concerns. The literature review shows that the quantitative and qualitative decline in groundwater is a global crisis. As a result, the factors affecting the quantitative and qualitative decline in groundwater range from climate factors to socio-economic factors.In the current research, find an answer to the poor condition of the Isin Plain aquifer by looking at the relationship between some hydrological factors and changes in cultivation pattern of the region is the main goal. For this purpose, the water table and EC of groundwater were interpolated using geostatistical methods. Using satellite imagery, the trend of culture pattern changes over time was obtained. Finally, the relation between the factors on the Isin plain was established. Material and MethodsFor this purpose, the quantity and quality of groundwater in eastern and western Isin plains were interpolated using the Kriging and IDW methods, during the four statistical years of 2004, 2011, 2018, and 2021 and the time series of 2004-2021. The RMSE statistic was used to evaluate the performance of the methods.Then, satellite images and ground truth data was used for land use change classes to investigate the land use changes during the cropping season, along with the determination of changes in the quantity and quality of groundwater in the eastern and western Isin plains for the mentioned years. Satellite data including Landsat 5 multi-temporal satellite images in 2004, 2011, and 2018 and Landsat 8 and Sentinel 2 images for February 2021 were obtained from the USGS.Following preparation of the related images using the flash module, atmospheric and radiometric corrections were performed. Then, the corrections information was extracted into the text file appended to each image. With field survey, the coordinates of the representative pixels were determined and seven land use classes of gardens, vegetables, bare lands, residential and industrial areas, saline lands, and Prosopis Cineraria and Juliflora species were determined. The maximum likelihood classification method was used to separate seven main land use classes based on 127 training samples. For the purpose of assessing accuracy, an error matrix was created for the producer's accuracy, the user's accuracy, the overall accuracy, and the kappa coefficient calculation. Finally, to examine the relationship, the land use map and the groundwater and EC interpolation maps were overlapped into the Arc Map software environment. Results and DiscussionBy comparing the interpolation methods of IDW and Kriging with the RMSE validation technique, it was found that the best interpolation method for estimating water table and EC is Kriging, followed by the IDW method. A review of the land use maps of the Eastern and Western Plains of Isin showed the increase and decrease of different land use categories over the years under study. The overall accuracy and Kappa coefficient were over 82% and 0.79, indicating the acceptable accuracy of the classification and maps obtained. The results of overlapping land use maps and spatial changes in ground water indicate that the location of agricultural land, especially gardens in the eastern Isin plain and vegetables in the western Isin plain, is compatible with the areas of having low water table. The results of overlapping the land use map obtained from Landsat 8 data and EC spatial changes showed the highest amount of EC in can be observed in Prosopis Cineraria and Juliflora species and residential and industrial uses in eastern and western Isin plain. The results obtained from Sentinel2 indicate that the value of EC was significant in the bare lands of eastern Isin and in the saline lands of western Isin. However, the increase in agricultural use, especially for gardens and vegetables, and the pairing with areas with the lowest water table indicates an over-extraction of groundwater for agricultural purposes. On the other hand, the significant extent of bare lands and the upward trend of saline lands, residential and industrial areas, and matching with areas with high EC and the adaptation of maximum EC with Prosopis Cineraria and Juliflora species uses may be a warning for poor condition of the Isin plain aquifer.

The main source of water in the Arsanjan plain is underground water, which has been exploited in the past with Aqueduct and now with numerous wells. For knowing about the quality conditions of these sources; multivariate statistical analysis and interpolation methods were used in three years with different rainfall. Factor analysis determined the key indicators of underground water quality and mapping was done with interpolation methods. The maps were classified using the Jenks optimization method of classification and the area of each class in each year calculated. Based on the results of factor analysis, EC, TH and Sodium concentration were selected with factor loadings of 0.843, 0.889 and 0.991, respectively. The RBF interpolation method for the sodium parameter was suitable in all three years of the study. For parameters of EC and TH, RBF-MQ method and LIP method had the least error in 2014 and 2015. Mapping spatial changes of the three mentioned parameters showed that in 2015, when the rainfall was lower than the average, the area of the regions with low values decreased. Due to the quantity and quality of its changes, sodium concentration parameter has a good potential to be used as an indicator of changes of the quality of underground water in response to climatic or management factors. In general, it is suggested that in assessment of the groundwater quality of Arsanjan Plain, the proximity factor to Bakhtegan Salt Lake, in addition to factors related to climate and watershed, should be considered.

Groundwater samples were prepared from 20 wells in the Gareh Bygone aquifer during the 2018 to 2020 years seasonally. Chemical characteristics of these samples including EC, pH, TDS, TH, SAR, SO4-2, Cl-, Na+, K+, Mg+2, Ca2+ and HCO3- were analyzed. The average of water salinity was 4.7dS/m, the acidity was 7.5, the average SAR value is about 6.7 and in some wells, this factor is about 10.6. Analysis of variance shows that all chemical characteristics except HCO3- have a significant difference. The principal component analysis identifies TDS, SO4-2, HCO3- and Na as the most effective variables in reflecting groundwater quality. Factor analysis also shows high TH, Na+, and HCO3-. Aquifer water resources are divided into three separate groups. The first group (with 97% similarity) receives the most impact from floodwater spreading and artificial recharge, and the other two groups (with 93 and 70% similarity) are located in the marginal areas or outside the floodwater spreading system. Despite poor management and uncontrolled discharge of the aquifer, at least in the central parts of the aquifer, which are more affected by artificial recharge by floodwater spreading, groundwater quality is more desirable.

The use of biochar as a soil amendment is one of the new methods to improve soil properties and increase plant yield. In this study, in order to evaluate the effect of adding natural biochar on soil properties and yield of Pamirian winterfat (Eurotia ceratoides) plant, an experiment in a completely randomized design were performed with 11 treatments by different levels of biochar (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10% by weight) and three replications in greenhouse conditions. After the end of the growing season, some physical and chemical properties of the soil (pH, EC, organic matter (%), lime, bulk deisty, particle density, and porosity percentage), germination percentage, and yield of E. ceratoides were measured. In all the studied traits of the soil (except for the particle density), and the characteristics of the E. ceratoides plant, the statistical difference between the various levels of biochar was significant (a = 0.01). Adding different levels of biochar increased pH, ECy, soil porosity percentage, soil organic matter, whereas decrased bulk density, lime percentage, clay percentage, sand, and silt.

Nowadays, with development of urban, industrial and agricultural, apply of groundwater is more important. So sustainability and development the exploitation of groundwater for types of different customers and goals, it is necessary that quantitative and qualitative characteristics it be investigated and evaluated.

Fuzzy Adaptive Neural Network (FANN) and Geostatistical method on based Geographic Information System are used for Komijan plain, Markazi province, Iran. The first, data 36 wells was collected from Rural Water and Sewage Company. Then using semi variogram types such as: gussian, linear, spherical and also Kriging and Co-Kriging methods, geostatistical model was evaluated using indicators: R2 and RMSE. Then, for Fuzzy Adaptive Neural Network model Membership functions such as:  triangular, generalized bells and gaussian was investigated and the best model was determined using indicators: R2 and RMSE.

According to results R2 and RMSE in geostatistical, spherical, linear and exponential modle was selected  as best for EC,  TDS and pH variables, repectively. Also on based semi variogram, Kriging method has a better performance than the cokriging method for all studied variables with high determination coefficient 0.73, 0.66 and 0.85 respectively for EC, TDS and pH and lower in RMSE. The results showed in Fuzzy Adaptive Neural Network, EC variable, the fuzzy generalized bell function with a correlation coefficient of 0.98 and mean square error of 144.59 in the test stage, is good. For TDS variable, gaussian function with a correlation coefficient of 0.98 and mean square error of 0.33 119 at the test stage is best. also for pH variable, the generalized bell function with a correlation coefficient of 0.99 and mean square error of 103.10 at the test stage has a better performance than other fuzzy functions in the modeling. By comparing the results of Geostatistical and Fuzzy Adaptive Neural Network, it can be seen that the FANN model has a higher efficiency than Geostatistical model.

Regarding the results of zoning maps, it is shown that in the northern part of the plain, EC has low, while in the central and west, EC is above 2000 µSiemens/cm. Also for TDS variable, t is low in the northern part of the plain, while in the south and southwest, is above 1000 mg /lit. Alos changes in pH value showed that variation of this variable is low and the highest level of pH is in the northern part and the lowest in the southern part.

Desertification, a manifest sign of land degradation is mostly due to unreasonable treatment, and in many cases, over-exploitation of natural resources, mainly soil, and water. Therefore, the purpose of this study was to identify and introduce the degree of impact of human activities from the perspective of water and land management in the desertification of the Sarvestan Sub-basin. Quantitative and qualitative changes in groundwater, detection of changes in farm field expanses, and the current state of water criteria (indicators: groundwater loss, EC, irrigation systems, SAR), and agricultural criteria (indicators: yield, cultivation pattern, use of inputs and machinery) using the Iranian model, the IMDPA. The water resources of the Sarvestan Sub-basin have decreased in quality (an increase of 2700 µS/m of salinity during the preceding 21 years) and quantity (subsidence of 10 meters of water level in 25 years). The cultivated area has expanded 196% from 1993 to 2016. An application of the IMDPA model indicates that the electrical conductivity index, with a numerical value of 3.4, had the highest effect (extreme condition), and application index of agricultural inputs and machinery with a numerical value of 1.7 had the lowest effect (moderate condition) in the Sarvestan Sub-basin. The water quantity with a numerical value of 2.56 was the dominant criterion, and along with the agriculture criterion, was placed in the moderate class.

The increase in population and natural factors such as drought, have led to critical conditions of groundwater in most parts of Iran. Considering that Semnan province is in an arid region like other dry parts of the country, it is more vulnerable to a water scarcity crisis, So, Semnan plain was selected to study the quality of groundwater. In order to study water quality, 19 observation wells were investigated. After entering the data into GIS software, using point maps and Kriging method, the zonation maps of groundwater quality were prepared. The study of quality parameters maps showed that groundwater quality was declined in this area as the wells in the study area are affected by the increase of TDS, SAR, EC and also the decrease in pH.

Gully erosion is one of the main types of water erosion and is known as one of the destroying forms of land degradation and soil loss in the world. Therefore, knowing the most effective factors on extending this type of erosion is utmost important. Beside, management and control of gully erosion require knowing the most effective factors on gullies extension. So, the present study was performed to determine the most effective factors on gullies in Khorrambid Watershed, North of Fars Province through measuring the permanent gullies during 13 years (2004-2016). Results showed that the average of gully length extension was 21.67 m throughout this period. This data indicated that the length of gully extension was 1.67 m per year. Further, it is determined that the length expansion of permanent gullies in this region was a function of bare soil and saturated electrical conductivity, using SPSS and backward multivariable regression. In conclusion, it is suggested different management solutions to increase the soil resistance against the erosion be prioritized in management and implementation plans such as increasing adoptable cover vegetation for the natural condition of the region and exclude the area to restore vegetation cover and pay more attention to control erosion in gully head cuts.

The cultivation of plants that are resistant in difficult environmental conditions is an effective solution for reclamation of lands; thus, recognizing the effects of cultivation of different plants on soil and vegetation cover could be a suitable guide to select proper species by experts. The aim of this research was to investigate the effects of range improvement and reclamation practices on soil and vegetation cover characteristics in Jannat Abad rangeland. For this purpose, four transects of 100-m length and two transects of 100-m length were established with 100-m intervals in the seedling area (Atriplex canescens and Haloxylon aphyllum) and the control area (natural vegetation), respectively. Along each transect, 10 plots of 4m2 were sampled. In each plot, the vegetation data including canopy cover percentage, litter, gravel, bare soil, dominant species, and plant density were measured. Soil profiles were dug at the beginning and end of each transect. Soil sampling was performed from 0-30, 30-60 and 60-90 cm depths. Then, soil chemical and physical properties including electrical conductivity, pH, organic matter, phosphorus, potassium, nitrogen, bulk density, clay, silt, and sand percentage. The collected data were analyzed by independent t-test with SPSS software. Results showed that the cultivation of Atriplex canescens caused an increase in canopy cover percentage, density, and potassium content in the first and second depths (P<0.01), and caused an increase in the nitrogen content of the first depth, organic matter of the second depth, electrical conductivity of the first and second depths, and silt percentage in the first and third depths (P<0.05). It also caused a decrease in soil pH and sand percentage of the second and third depths (P<0.05). The cultivation of Haloxylon aphyllum caused an increase in density, electrical conductivity of the first depth, and a decrease in clay percentage in the third depth (P<0.05), compared to the control area.

Managing the optimal use of water resources is one of the most important issues in sustainable development. Considering the importance of studying groundwater in the field of drinking, industry and agriculture, the study of water qualitative changes can be important for humankind. In this study, groundwater level depletion and electrical conductivity (EC) were used to investigate the quantitative and qualitative changes of groundwater in Karaj plain. The water level hydrographs were drown using Thiessen method based on the piezometric wells data and the groundwater depletion, the elevation contour line, and iso- electrical conductivity maps were provided using GIS. Quantitative changes were studied with reading of each well in different months in a 15-year period (2001-2016). The obtained results showed that the vast range of Karaj plain was depleted due to the lack of proper recharge as well as the over-exploration of groundwater. In addition, the relation between EC and anions and cations (such as Ca2+, Mg2+, K+, Cl-, Na+, SO42-, HCO3-) were determined. The calculated Standard Index of Annual Precipitation (SIAP) in five meteorological stations showed groundwater depletion due to rainfall reducing and drought. Electrical conductivity had direct relation with concentration of ions in all cases. According to the hydrographs, the average level of groundwater decreased to 1.02 m over 15 years and the groundwater level depletion consequently decreased the water quality.

Different plants have different effects on the characteristics of their surroundings, especially on the soil. Soil properties also have the different effects of these plants on them. In this research, the effect of capparis spinosa on the soil characteristics of three areas with different soil characteristics was evaluated. The under-floor soils of the capper plant in three depths of 0-30, 60-30 and 60-90 cm, compared to the non-vegetation soils, were taken in three different geographic regions with six replicates and a total of 108 depth samples, and in The laboratory measured some of their physical and chemical properties. SPSS software was used to analyze the data and to compare the measured characteristics with non-pairs F and T tests. The results showed that the effect of capper plant on the characteristics of saline soils is a significant reduction of salinity and soil salts, reducing SAR and simultaneously improving some of the characteristics of fertility, such as increasing the potassium available in these areas. Also, in soils with light and medium non-saline texture, significant increase in available potassium levels and SAR reduction were observed in the lagging soil.

Nowadays, water quality is one of the key issues in most regions all over the world. Because of its high relation with human health and also have important role in management and exploitation of resources. This research has done first time in Pasargad city located in 105 km of eastern north of Shiraz. In order to determine drinking water quality factors using data mining technique, results of this research have obtained using Quest decision tree in Clementine software(12 version) and showed most effective factors of drinking water in this region is function of total harness and electrical conductivity. In this way, if total hardness in this city is less than 282.232 parts in million and electrical conduction is less than 822.787 micro mohs in centimeter, this water will be suitable for drinking. Therefore recommended more noting to refine and decrease the hardness of water for human drinking water, moreover continuous refining in periodically regular sampling of water resources in this city should be noted.

Recognizing quality of groundwater as one of the most important and vulnerable sources of water supply in recent decades is a necessary and important issue. Water purification is sensitive and time consuming; therefore, investigation of the quality of groundwater supply is essential. In this research, in order to study chemical compounds of groundwater, 21 observed wells were sampled in the summer of 2013 year and important parameters of samples were measured and calculated for agricultural and drinking uses. Also Piper diagram was used to determine hydrochemical facies of the groundwater area. The results showed that dominant type of groundwater hydrochemical facies of region was calcium sulfate (Ca-S04). According to World Health Organization standard, among wells of region just H9, L15, O12, and L6C wells was suitable for drinking use and these wells in terms of sodium hazard and change of soil structure for agriculture use, had a good to admissible situation . Also, groundwater of that region had moderate permeability index; therefore, it should be used for soil irrigation with sufficient permeability and cultivation of salt tolerant plants.

Electrical conductivity (EC) is an important factor in river engineering, especially studying of river water quality. In this study we studied and evaluated wavelet neural network to predict the electrical conductivity of the Kakareza river (in lorestan), and the results were compared with results of artificial neural network model. For this purpose, hydrogen carbonate, chloride, sulfate, calcium, magnesium, sodium and flow rate at monthly scale during the period (1969-2015) as input and output parameters were selected as electrical conductivity. The criteria of correlation coefficient, root mean square error and of Nash Sutcliff coefficient were used to evaluate and performance compare of models. The results showed that wavelet neural network model has the highest correlation coefficient (0.977), the lowest root mean square error (0.032 ds/m) and the highest standards Nash Sutcliffe (0.847) became a priority in the validation phase. The results indicate acceptable capability of wavelet neural network models to estimate the electrical conductivity of river water.

Recognizing of critical zones of groundwater quality is one of the most important issues about researches in water fields. The goal of this study is to determine the spatial and temporal variation of groundwater quality factors such as electrical conductivity and chloride ion contents using the best suited geostatistical estimation in Kerman plain on 10 years period (1996-2006). Also, the best variogeram model and parameters related to model of EC and Cl contents will be determined. Findings of variography analysis for Cl contents of groundwater quality data in the beginning and the end of study period showed that the exponential structure is the best spatial model fitted to this parameter. Thus, its effect range increased from 101700 to 106200 meter and sill contents decreased from 2.246 to 1.698, during 1996 to 2006. The best model fitted to electrical conductivity spatial structure became exponential in 1995-1996 and spherical in 2005-2006. The results of geostatistical analysis show that effect range and sill contents of EC decreased from 79800 to 37500 meter and 0.84 to 0.608, during 1996 to 2006, respectively. Comparing of interpolation methods of groundwater quality data introduced log kriging method as the best approach for Cl and EC zonation maps. Cl zonation maps show an increasing trend of Cl content in all plain areas in 10 years period. Thus, Cl concentration in the input region of plain increased in the range of 3.03-13.01 in 2006.Intensity of Cl content occur in north outlet of plain near well numbers 27, 28, and 33, and Cl critical core of western south of plain near well number 19 show an increasing trend. Our findings showed an increasing in EC content, especially its spatial spreading in west and north outlet of Kerman plain and Kerman city in 10 years period.

Common causes for groundwater quantity and quality changes are infiltration through the seasonal floodwater, effects of the artificial recharge projects and adjacent aquifers, and groundwater extraction for deferent uses. However, recognizing the impact of their contributions to these changes can be often challenging. Still, to understand the changes, monitoring groundwater level and several chemical factors are taken into consideration. Certain problems of course can complicate the analysis of the observations; for instance, insufficient data and manually prepared and measurement intervals can degrade the accuracy of such observations. In this paper, device-measured daily time series of Electrical Conductivity (EC), Temperature (T) and Groundwater Head (GH) are analyzed. The main purpose is to evaluate the groundwater changes and its relation to the processes on the aquifer surface in an arid region. Two wells (PZ2 and W20) with 1,200m distance from each other selected and installed a sensitive device for recording the groundwater level, temperature and salinity fluctuations. Time series of changes from December 2012 to July 2013, were analyzed. Groundwater head in PZ2 showed a decline but in W20 showed a minor rise. Salinity variations were different and were 15.3mS/cm in PZ2 and 1.7mS/cm in W20. The backdrop of increased salinity in the surface layers of groundwater in PZ2 identified and showing a correlation between groundwater head and salinity fluctuation with 83.5% R squire.

This study aimed to investigate the relationship between expression of soil salinity factors and vegetation cover in Foojerd watershed. To this end, the vegetation types in the region and the formation of relatively homogeneous in terms of soil and topography, soil and vegetation were sampled by a systematic random sampling. The samples according to the area consists of homogenous units were determined. In each plot characteristics of range species and percentage of vegetation cover were recorded and soil profiles were dug. Depending on the depth of the soil profile and the depth of the roots of the plants were sampled and conductivity, exchangeable sodium, sodium absorption ratio and absorption of sodium in each of the soil samples were measured. Pearson correlation coefficient of salinity and vegetation type and percentage of vegetation cover were calculated using SPSS18.0 software. The results showed that vegetation has a negative correlation with soil salinity factors. Based on analysis of variance and Duncan were revealed that test the type of plant species were depended on soil electrical conductivity and sodium absorption rate and the percentage of canopy cover was affected by soil electrical conductivity and exchangeable sodium content. So soil sodality is the most important limiting factor to grow vegetation in Foojerd watershed.

Heavy exploitation is a major cause of degradation and destruction of rangelands. Rangeland overgrazing by livestock destroyed vegetation and cause bare soil which exposed to erosion. To studying the effect of grazing on physicochemical properties of soil, a study was conducted at Zagheh research station located in Lorestan province. For this purpose, in both grazed and protected area, 10 soil samples was done based on randomized systematic method from 0 to 30 cm soil depth which transferred to the laboratory. In laboratory soil properties such as soil texture, bulk density, total nitrogen, the C / N, P, K, lime, acidity (pH), electrical conductivity (EC), were measured. Data analysis was performed in SPSS software. The statistical results showed that soil texture and soil pH was not significantly affected by grazing. However the bulk density, organic carbon, total nitrogen, the C/N ratio, P, K, lime and electrical conductivity (EC) significantly affected by grazing.

The used of unconventional waters in the agricultural lands not only reduces the environmental hazards but also increases the productivity. This research was aimed to assess the effects of wastewater, saline water and brackish water on some soil properties including organic matter, bulk density, and electrical conductivity. Therefore, five study sites were selected. The treatments consisted of control, irrigation with saline water, brackish water, and wastewater as well as mixed irrigation of wastewater and saline water. Five profiles were dug in the study sites. In each profile, two samples were taken from two depths of 0-30 cm and 30-60 cm. The results showed that irrigating with wastewater led to improved soil properties in terms of organic matter and bulk density, as compared with other treatments. There was no significant difference in pH among all treatments. However, the amount of Electrical Conductivity of saline water in surface and deep layers of soil was 17.57 ds/m and 5.5 ds/m, respectively. This large difference between the two depths in saline water treatment represents the EC downward trend from surface to depth. This trend was constant for the brackish water and wastewater treatments.

Yazd – Ardakan Plain is located in the center of Iran. That most of the population in Yazd Province are concentrated in this plain. So Temporal and spatial study of Groundwater Quality is necessary. In this research, 30 wells with suitable distribution were investigated and quality zoning was done using simple kriging method analyzed for indexes of EC, TDS and SAR during 2002 -2010 statistical period. According to the obtained results in this research,, Groundwater Quality in Yazd – Ardakan Plain has been decreased from South West and West to North, North East and East. reason of for this subject is Neogene formations in the East and Salt Desert around SIAH KOH desert in the North And also the direction of groundwater flow to the outlet area in the north of the basin, which also helps. And reduce the quality of groundwater. Maximum average for indicators of EC, TDS and SAR were occurred in years of 2002, 2007 and 2002, respectively and Minimum average for indicators of EC, TDS and SAR were occurred in years of 2003, 2003 and 2009, respectively. It seems that the trend of the three indicators follows from groundwater fluctuation pattern and drought. The three studied parameters studied have upward between the years 2005 to 2007 Upward and then to have downward.