جستجوی مقالات مرتبط با کلیدواژه "groundwater" در نشریات گروه "اکولوژی"

Estimating the amount of evaporation from water resources is one of the important and key factors in calculating the water balance and managing water resources in each region. In order to calculate the average evaporation from water resources in Kashan plain and to check the amount of enrichment, the information of stable isotopes of water molecules was used. In this study, 42 water samples were collected from groundwater, Playa Lake and Serajeh salt pan in order to analyze the hydrogeochemical and isotopic characteristics. The amount of 18O isotopic enrichment factor was determined based on and the amount of deuterium based on . According to the results, the overall enrichment value due to evaporation, under the specified conditions and an average annual temperature of 30°C, was determined to be -16.4‰ and -82.25‰ for oxygen-18 and deuterium, respectively. Additionally, based on the Rayleigh distillation, the amount of water losses due to evaporation was calculated based on the differences between the initial sample and the 18O value of the Playa using the simplified Rayleigh equation. Since the remaining water fraction was found to be 0.40, hence the water loss rate in the northeastern part of the aquifer was estimated to be 60 percent.

Groundwater pollution is severely affected by different land uses, so that it is created widespread contamination in different areas in groundwater and endangers the health of human, livestock and other living organisms. In this study, the nitrate content of 55 water sources in Sirjan plain aquifer was investigated. Then, 5 types of land use were identified in Sirjan plain. Then, the polygon of Sirjan plain was mapped based on 5 types of land use to determine the role of each land use in the amount of groundwater nitrate in Sirjan plain. Then the amount of area and nitrate of different land uses were divided into 7 classes. The results showed that range land use in Sirjan plain has the highest level in aquifer and the lowest level of planting forests in Sirjan plain aquifer. Considering the minimum and maximum nitrate distance in Sirjan plain, the results showed that range land use has a lot of nitrate spatial variability compared to other land uses, and industrial land use has the least spatial variation in nitrate compared to other uses. In general, according to the mean amount of nitrate in Sirjan plain aquifer, the results showed that the minimum nitrate mean in different land uses of Sirjan plain is related to agricultural land use with 7.53 ppm and the maximum nitrate mean in different land uses of Sirjan plain is related to industrial land use with 10.24 ppm and the average nitrate level in planted forests, range and residential land uses with small changes is between agricultural and industrial land uses. In general, among all nitrate classes in Sirjan plain, the results showed that range land use has the highest percentage of land area, and industrial and planted forests land uses have the lowest percentage of land area.

Groundwater is the main component of sustainable development in Iran. Due to population growth, over-exploitation, reduced precipitation, and inappropriate cultivation practices, water storage has significantly declined. Therefore, it is imperative to model groundwater and predict the future state of the aquifer for effective management. In this study, we have modeled the qualitative and quantitative changes of the Kashan aquifer. Based on the hydrological and hydrogeological conditions of the Kashan plain aquifer, we developed a groundwater quantity and quality model (2009-2015) under stable and unstable conditions using the MODFLOW and SEAWAT models in the GMS software. The models were validated through statistical evaluation, demonstrating their accuracy in modeling. Once the models were validated, we assessed the status and quality of the aquifer for the next period (2016-2023) by considering various practical scenarios. Applying the current trend scenarios revealed a projected decrease in aquifer volume to 1.556 Mm3 and an average increase in salt density of quality wells to 160.33 ppm in the next period. Conversely, when simulating the scenario of shutting off wells for a month, the aquifer volume was projected to increase to 0.0147 Mm3, and the salt density of quality wells would decrease to an average of 42.27 ppm during that one-month period. These results highlight the model's capability to accurately recognize and predict observed and calculated outcomes. The expansion of saline water in the northeastern part of the aquifer has resulted in a decline in both quantity and quality in that region. Finally, implementing multiple management and scientific scenarios concurrently is crucial to prevent further deterioration of the quantitative and qualitative status of water resources in this region.

Due to population growth, increasing welfare, development of industries and agriculture along with climate change, groundwater resources are always changing in terms of quantity and quality. Therefore, it seems necessary to study the quantitative and qualitative changes of groundwater to manage. For this purpose, in the present study to study the groundwater quality changes in Bijar-Divandere plain, in terms of sedimentation and corrosion, using the information received in the years 2009 to 2018 and each year for the two months of June and October as water months and Water scarcity has been addressed using the Geographic Information System (GIS). Also, by evaluating various indicators to determine corrosion and sedimentation, valid indicators such as Langelier, Reisner and Pocorius for industrial use and sedimentation and corrosion analysis were studied in this study. The results of the mentioned indicators showed that the groundwater of the western areas of the plain is prone to corrosion and the eastern areas were prone to sedimentation and the Reisner index showed the water quality of part of the center of the plain was neutral. It was suggested to use aeration to remove iron and manganese, cathodic protection, priming, glazing and painting of the desired facilities in the western parts of Bijar-Divandere plain to prevent water corrosion. Also, for the central regions to the east of the plain with water deposition properties and adverse effects on agriculture, industry and health of the region, the use of sedimentation inhibitors such as the use of phosphate compounds and less harvesting of water resources was recommended.

Damghan plain located in Semnan province and due to lack of water resources need to study the status of water resources for better management. Water resources used in this area supplied from springs and wells. the present study aimed to prepare a spatial distribution map of groundwater quality parameters and compare them in different parts of the aquifer surface using geostatistical methods. Measurement parameters in wells, springs and qanat are (TDS, pH, EC, HCO3-, Cl, Ca++, Na+, %Na, SO42-). The results of descriptive statistics in deep well showed that the highest percentage of changes related to Mg and SO42 variables and the lowest percentage of changes were related to pH. The highest percentage of changes in the semi-deep well is related to HCO3 variable and in the spring it is related to Cl. Also, the highest percentage of changes in Qanat is related to chlorine and calcium, while the lowest percentage of changes is related to TDS. The highest percentage of changes in semi-deep well was allocated to bicarbonate anion and the lowest percentage of changes was related to pH. Among the underground water sources, the spring showed better results in terms of regression coefficients and variogram models. The results of the time changes indicated that the measured qualitative parameters had the most changes in autumn and late spring. The general result of this research indicates that the kriging method with spherical semi-variograms is a suitable method for spatial evaluation of groundwater quality variables in Damghan plain.

Groundwater is the main source of fresh water in Nekarud region of Mazandaran Province. Population growth and the development of agriculture and industries has had a negative impact on the quantitative and qualitative characteristics of underground water in Nekarudd plain. Management and of these resources is necessary and unavoidable. Therefore in order to prevent environmental damages resulting from pollution and extraction of underground water resources in this region, principled planning should be done in the region. In this research, using three models DRASTIC, SINTACS and SI, the vulnerability of Nekarud plain aquifer was evaluated. For this purpose, first, the necessary parameters for the mentioned models including groundwater depth, nutrition, unsaturated zone, soil type, aquifer environment, topography, hydraulic conductivity, and land use were assessed and scored to prepare the overlay map. The nitrate and pH data of 2013 and 2014 were also used to validate the outputs of the models. The results showed that the DRASTIC model has the highest correlation value with nitrate, which is the main cause of groundwater pollution, and the north and northwest regions of the basin has the highest vulnerability value with 52.97%. The Mann-Kendall test to determine the trend of elements also showed that there is no trend of nitrate elements. But the value of ZS index for pH in 2013 was equal to 8.638 and it has an increasing trend. This means that this index had an increasing and significant trend at the level of 0.95 in 2014. The general result showed that DRASTIC is a suitable model for evaluating the vulnerability of the plain and planners and decision makers can use it as a suitable and cost-effective solution to prevent the increase of pollution.

Today, due to uncontrolled withdrawal of groundwater resources and declining water table, especially in arid and semi-arid regions, planning and management in the consumption of these valuable resources are of great importance, which requires a study of the behavior of the aquifer in relation to the changes made on it. The purpose of this study is to investigate the efficiency of random forest algorithm in predicting the water table of the unconfined aquifer of Birjand plain and to compare the results with two models of decision tree and artificial neural network. In this regard, first, the input data to the model was collected on a monthly basis during 2010-2011 until 2016-2017 water years, and after checking the trend and removing it, to create the mentioned models, the rattle software package in the statistical software R was used. The results of simulation using the random forest algorithm based on evaluation criteria of R2=0.714, RMSE=0.003 and NS=0.598 (m) show that this algorithm has a relatively high ability to simulate the aquifer water table. Comparing the results of this algorithm with two decision tree and artificial neural network models, it can be seen that the results of the random forest algorithm compared to the decision tree model with R2 = 0.5409, RMSE = 0.0072 and NS = -0.0187 (m) is more consistent with the actual water table of the aquifer and is in line with results of the artificial neural network with R2 = 0.7055, RMSE = 0.003 and NS = 0.6046 (m).

Optimizing the piezometric wells in the groundwater monitoring network is important in terms of reducing maintenance costs and improving efficiency and increasing the speed of data updating. Statistical methods or PCA are commonly used to identify significant wells. In geostatistical methods, optimization is performed according to the location of the samples but the temporal information of the wells is not taken into account. In the PCA method, indicator wells are determined in terms of temporal information of wells. In this research, an approach based on a combination of these two methods is presented to consider the spatiotemporal information of wells. The present study was conducted by obtaining data from 47 wells related to the first aquifer of Sarab plain in 1397 in three main stages: 1- Exploratory spatial data analysis (ESDA), 2- Determining the priority of wells based on temporal information of the wells in the neighborhood by PCA method, 3- Investigating the surface accuracy changes by kriging method assuming the removal of wells with low temporal priority. The results showed that 9 wells of Sarab plain (19%) have relative importance less than 0.3. By removing these wells and evaluating the RMSE error in the deleted points, the value of these wells can be calculated with 46cm error through spatial autocorrelation information. Therefore, the removed wells do not enter much spatial information, and by removing them, it is possible to increase the accuracy of measuring the water level in other wells and save time and cost with the same accuracy.

A large part of Iran suffer from salinity which threatens sustainable agriculture and food security. Overexploitation of groundwater, where fresh and saline aquifers are adjacent to each other increasing saline water hydraulic gradient and solute transport toward fresh aquifer and increasing salinity. In Qazvin saltmarsh salinity is expanding toward upstream lands under the mentioned mechanism. An interception drain has been constructed in area in order to drive out saline water and control salinity. The purpose of this study is to assess interception drain ability in controlling salinity and the effect of hydraulic gradient increase and decrease on salinity expansion toward upstream lands. Thus first using observed data the HYDRUS-2D model was calibrated and validated. Then in six treatments, the effect of increasing and decreasing upstream input flow (10%, 20%, 30%) on drain operation in 5, 10, 15 and 20 year intervals was simulated. According to results at all time intervals, the greater the upstream inflow, the more solutes are leached out of area by interception drain. The simulation results also showed that the initial soil salinity at the drain flow decreased about 16.1 ds/m after 20 years. As upstream input flow decreases 10%, 20% and 30% this amount (16.1 ds/m) decreases 11%, 17% and 25% respectively. While increasing upstream input flow decreases salinity 22%, 28% and 40% further.

Groundwater is an important source of exploitation in arid and semi-arid regions. For this reason, in order to maintain groundwater quality and its optimal management, it is important to know their spatial and temporal distribution and their monitoring and zoning should be considered as an important principle in the country's water resources planning. The aim of this study was to zoning the electrical conductivity of groundwater in the Mashhad plain aquifer using 5 methods of distance inverse geostatistics (IDW), local estimator (GPI), general estimator (LPI), kriging and cokriging and also evaluating the gene expression programming model in predicting this The parameter is using spatial data. For the present study, data from 122 observation wells in the aquifer area of Mashhad plain were used. To compare the methods used, two squares evaluation criteria were the mean squared error (RMSE) and the mean absolute error (MAE). The semi-variable plot in GS + showed that the electrical conductivity data fit best in the spherical model. The results of the present study showed that among the mentioned methods, the inverse distance method (IDW) with error rate RMSE=0.3 mos/cm and MAE=0.16 mos/cm and then the model of gene expression programming with RMSE=275.54 mos/cm MAE=223.15 mos/cm with the highest accuracy and local estimator method (GPI) with RMSE=996.11 mos/cm and MAE=755.56 mos/cm, had the least accuracy in this field.

Groundwater is one of the main sources of drinking water, industry and agriculture in Iranchr('39')s arid and semi-arid regions. Improper harvesting and entry of pollutants into these waters have caused changes in the quality of these waters in different regions. The purpose of this study is to compare definitive introspection and statistical methods for zoning qualitative data of Borkhar plain in Isfahan province. In this study, the qualitative information of 29 groundwater wells was used to evaluate the qualitative parameters including: EC, TDS, Cl, SAR, SO4, Na, Mg and HCO3 in 2006 and 2016. GS + software and GIS environment were used to determine and map zoning maps using different introspection methods. Then, the qualitative parameters were evaluated using definitive internalization methods and zoning statistics and using error evaluation criteria, the best method for each qualitative parameter in each period was determined and their zoning map in the GIS was drawn. The results showed that in definitive internalization methods in all qualitative parameters, the RBF method provided less error. However, in the geo-statistical method, the results of fitting the models to the mutual variogram showed that different qualitative elements in 2006 and 2016 follow different models. Also, a map of qualitative characteristics was drawn during the study period and the results showed that the average qualitative characteristics of EC, TDS, Cl, SAR, SO4, Na, Mg and HCO3 in 2006 were equal to 942, 281.7, 27.28, 6.428, 10.409, 22.602, 8.936 and 4.178, which in 2016, this amount is equal to 1002, 352.4, 21.604, 6.059, 10.645, 18.869, 5.185 and 7.126, which indicates a decrease in water quality.

Optimal design of groundwater monitoring network that is capable of providing accurate and informative data is crucial to improve our understanding of complex groundwater systems. In this study, a geostatistical method to optimize a groundwater quality monitoring network in Shamil-Takht plain, Hormozgan province were used. This study uses the spatial variance of collected data from the field to identify areas that are not covered and lack information. The kriging variance and the vulnerability maps were combined and the final map was used to design the optimum network. Selection of the best-fitted model was based on the values of the RMSE. This approach has been used to assess the electrical conductivity (EC)-as the representative of the most important quality parameters- monitoring network. The results show that 23 wells can be removed from the primary sampling network with 44 wells. On the other hand, 15 wells have been added to cover areas without information. As a result, the number of wells in low density areas has increased. Based on contaminant sources available in the plain, six new sites have been proposed to monitor the potential contamination from cemeteries, health centers, food and livestock industries.

In order to investigate the effect of flood in March 2019 on quantitative and qualitative changes of groundwater, the floodplain at the end of Gorganroud river basin, which was naturally exposed to floods, was selected. To investigate changes in groundwater quantity and quality, 17 and 11 observation wells with suitable distribution in the study area were selected, respectively. Then, quantitative (groundwater level) and qualitative data (11 physicochemical parameters) of wells were collected in two periods before and after the floods. First, groundwater level changes in two periods were evaluated by paired T-test and average groundwater level of the plain. Then, physicochemical characteristics changes in two periods were evaluated using paired T-test. Finally, hydrogeochemical changes were assessed using Gibbs, Durov and Piper diagrams, and the water quality for agricultural and drinking purposes were investigated using Wilcox and Schoeller diagrams. Paired T-test results showed that the groundwater level in 88.2% of the observation wells after the flood had a significant increase. This has increased the groundwater level as well as the unit hydrograph of the plain (about 2 meters) after the flood. The results of changes in groundwater quality parameters showed that the amount of EC, anions and cations (except NO3) were decreased in most of the observed wells after the flood. This has reduced the hardness of groundwater but has not had a significant effect on the type and hydrogeochemical facies of floodplain groundwater. The reason can be the hydrochemical similarity of infiltrated water and groundwater of the plain aquifer.

Groundwater is an important part of the world's renewable water, accounting for about 60% of available renewable water resources. Due to the importance of this issue, this study was conducted to investigate the quality of groundwater resources in Kamyaran plain, Kurdistan. For this purpose, six effective parameters in determining water quality were analyzed. Then, by examining the Root Mean Square Error (RMSE) of two well-known interpolation methods (Kriging and Inverse distance weighted (IDW)), the IDW method was selected for zoning. The results showed that the electrical conductivity and total dissolved solids factors had many fluctuations in this plain and its range was identified for EC from 15000 µmhos/cm to 600 µmhos/cm and for TDS from 10200 mg/lit to 45 mg/lit. Using the drinking water quality standard, it was found that the concentration of the studied qualitative parameters in the groundwater resources of this plain, except for the pH parameter in some villages, is within the permissible range. Mainly the northern and southern parts of the plain have lower water quality. Therefore, groundwater resources quality planning and management of these areas is a priority.

Groundwater resources are the largest available freshwater reservoir on the Earth. Therefore, the management of these resources and their quality control is an essential issue. The purpose of this study is to investigate the trend of changes in groundwater quality parameters by Mann-Kendall test and qualitative classification of Boroujerd-Dorod plain using GQI index. For this purpose, the values of different parameters including chlorine, sulfate, acidity, total hardness and total dissolve solid from 41 sources during the period of 1993-2016 were used. The results showed that based on Mann-Kendall test, the acidity and chlorine parameters had positive Z value, and the acidity trend was significant at 95% level, while other parameters had negative Z value with decreasing trend. According to the GQI index, all parameters in the year 2016 were in accordance with ISIRI criteria. Based on the ranking of different parameters, it was found that TH, pH and EC had the greatest impact on the quality of groundwater resources in the studied plain. From the spatial point of view, the highest concentration of qualitative parameters except pH is in the center of the plain, and the northeast area of the plain is also prone to high pollution compared to other parts of the plain, especially in terms of cations and EC. Based on Schulerchr('39')s classification which was used to validate the GQI results, the quality is located in good and acceptable class, which confirms the result of this index.