Showing 145 results for gh
Ali Kamali, Dr Mehdi Mokhberi, Dr Abbas Ghalandarzade,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
Marls are one of the problematic soils that undergo more erosion due to their deformability and sensitivity to humidity and weather conditions. The effects of these soils have been observed on subgrades of pavements, abutment of dams, foundation of high-rise structures, the interaction of soil-structure and etc. The strength and deformation of marls are more effective to moisture content. In addition, the dynamic parameters of theses soil are considerable as well as static geotechnical specifications. Soil dynamic parameters can be obtained from both laboratory experiments and field experiments. With the aim of understanding the dynamic behavior of marl soils, this study was carried out to evaluate the marls of northwest region of Shiraz City which is mixture of marls containing the expansive anhydride gypsum. For this purpose, the laboratory cyclic triaxial test and in situ downhole test has been performed. The results showed that for normal consolidated marls, with increasing the confined pressure from 400 to 600 kPa (increasing soil depth), the shear modulus increases from 50 to 200 kPa. In addition, the behavior of the damping ratio is relatively different for strains less than and greater than 1%, but in general, for strains higher than 1%, the damping ratio decreases from 0.21 to 0.18 with the increase confined pressure from 100 to 600 kPa.
Mehdi Talkhablou, Seyed Mahmoud Fatemi Aghda, Habibulah Heidari Renani,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
The stabilization of underground spaces is one of the most challenging topics in engineering geology. There are several methods to determine the type of tunnel stabilization system, but most of these methods have several weaknesses. Therefore, the development of a method that comprehensively considers almost all parameters influencing tunnel stability and their interdependencies has not received sufficient attention. The aim of this research is to investigate the parameters influencing the stability of tunnels using the rock mechanics system method. In this paper, 6 tunnels with different geological characteristics were selected. The effective parameters on the primary stabilization of these tunnels were coded using the ESQ method. Subsequent analyses were performed using the RES rock engineering system method to estimate and evaluate the optimal tunnel stabilization system. The results showed that parameters such as weathering of the joint surface, backfill and joint spacing played a more effective role than other parameters. For comparison, the analyses were also carried out using the RMR rock mass ranking method. The comparison between the results of the RES and RMR methods showed that the results of the RES method are in better agreement with the actual tunnel conditions and the shotcrete thickness of the proposed stabilization system of the studied tunnels. Since there is no limit to the number of input parameters in this method and, on the other hand, the mutual influence of the parameters on each other is considered, the relationships obtained from the RES method in this research can be effectively used in engineering projects along with other methods.
Mohadeseh Sadeghi, Naser Hafezi Moghads, Mohammad Ghafoori, Mehrdad Amiri, Ali Bashari,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
The design of underground or terrestrial structures on the rock bed depends on the physical and mechanical properties. Considering the mining method in Tabas coal mine extraction method is long and destructive, the evaluation of the geomechanical properties of the rocks is more necessary. In this research, the characteristics of the rock units of the eastern tunnel No. 3 of Tabas coal Pervadeh mine were investigated. In this study, 3 samples of shale, sandstone and mudstone were examined. Considering the importance of the subject in this research, new experimental relations have been proposed, and their application shows desirable results. In order to obtain geomechanical characteristics and empirical relationships, physical tests such as porosity, water absorption percentage, unit volume weight, and mechanical properties such as uniaxial compressive strength, point load index, Brazilian tensile strength, direct cutting test, durability and brittleness index were carried out. To achieve the desired objective, the most appropriate relationships are presented using the regression method. Statistical analysis shows good correlation between different parameters in shale, sandstone and mudstone samples.
Dr Nasrollah Eftekhari, Dr Sasan Motaghed, Dr Lotfallah Emadali, Dr Hasi Sayyadpour,
Volume 16, Issue 2 (Summer 2022 2022)
Abstract
In the variability of earthquake hazard analysis results, ground motion prediction equations play an important role. Selection of appropriate prediction relationships for the region can lead to stability and accuracy of earthquake hazard analysis results. In this study, different prediction relationships were investigated and analyzed for earthquake hazard analysis in Ahvaz city. These relationships were ranked based on the criteria of logarithmic probability, Euclidean distance and deviation information in different periods. Then the most efficient relationships were selected by data envelopment analysis (DEA) method on the basis of differences in the obtained results. Out of 67 possible relationships, 5 were identified as suitable relationships for earthquake hazard analysis in the Ahvaz urban area. Then, a special efficiency criterion was used to determine the weight of these relationships. The results of this study can help to reduce to a large extent the uncertainties involved in analyzing the seismic hazard of the area studied.
Kamal Ganjalipour, Seyyed Mahmoud Fatemi Aghda, Kamal Nabiollhi,
Volume 16, Issue 3 (Autumn 2022)
Abstract
Electromagnetic methods in applied geophysics are advancing rapidly. Since the TDR system has grown, its use has led to innovative applications and comparisons with other previous measurement methods. A TDR system consists of a radar (electromagnetic) receiver and generator, a transmission line, and a waveguide. The electromagnetic pulse generated from inside the conductor cable moves towards the waveguide and is tested through the waveguide into the environment under test. In the last few years, the use of the TDR system to identify water leakage situations has been expanding. In this article, by performing tests on two-strand telecommunication cables as TDR sensors, the ability and accuracy of the time domain reflectometry method in detecting leakage situations has been evaluated. In this research, the two-stranded cable was buried under GC gravel clay material, and by increasing the percentage of soil moisture stepwise at two points, the sensitivity of the TDR method to the changes in moisture around the cable was investigated. Based on the TDR waveforms, the points of reflection coefficient changes are located at the distances of 9.5-9 and 4.5 meters, which is completely consistent with the actual distance of the test points. In this research, TDR moisture meter made by soil moisture company model 6050x1 was used. The results of this research show that the TDR method has the ability to be used as a monitoring system to detect leakage in dams, dikes and other geotechnical structures.
Dr Mohammad Fathollahy, Mr. Habib Rahimi Menbar, Dr. Gholamreza Shoaei,
Volume 16, Issue 3 (Autumn 2022)
Abstract
Shear strength parameters are important for assessing the stability of structures, and are costly to calculate using conventional methods. In this research, simple geotechnical techniques and artificial intelligence were used to calculate the angle of internal friction and soil cohesion without the need for more complex testing. To this end, intact samples from 14 boreholes in Bandar Abbas, which had undergone primary geotechnical testing and direct cutting, were selected and used to train neural networks. 195 networks were trained in in this research. To achieve the best performance, feedforward neural networks were first trained in single and double layer modes with a low number of neurons in the middle layer, and the TRAIN BR function was selected due to the high ratio of R (0.97). Then, by incorporating additional layers, the Median model was trained using configurations of 3, 4, and 5 layers, each with varying numbers of neurons in the intermediate layer (50, 40, 30, 20, and 10). The results show that the four-layer MLP network gives the best results, for this mode R training 1, the test R is 0.90 and the total R is 0.98. Finally, to validate the neural network, 15 samples were selected and the input parameters of the network were trained in the optimal states of 2, 3, and 4 layers, then the output of the network was evaluated. For cohesion prediction, the neural network in 4-layer mode (R2=0.99) and 2, 3 and 4-layer networks (R2=0.99) have the best output for the friction angle.
Armin Aziminejad, Omid Makhdoom, Panan Zarfam, Abolreza Sarvghad Moghadam,
Volume 16, Issue 3 (Autumn 2022)
Abstract
In most current seismic codes, the stiffness and strength of seismic members are considered to be independent, so that a change in the strength of the members does not result in a change in the stiffness of the members. Recent studies show that these parameters are interdependent. Therefore, the way these parameters are calculated and the arrangement of centers of mass, stiffness and strength can be effective in determining the seismic response. In this research, buildings with different levels of normalized yield eccentricity (ed/A) were designed according to the ASCE/SEI 07-22 seismic code (Code Design models) and compared with the Balance-25% and Symmetric Strength models. The results of the nonlinear static analysis and incremental dynamic analysis showed that the average spectral acceleration at the level of collapse in the Balance-25% and Symmetric Strength models increased by approximately 18% compared to the Code Design model. Therefore, these models are safer than the Code Design model. In addition, the average of the peak rotation of floors and the maximum inter-story drift at the collapse level in the Balance-25% and Symmetric Strength models has decreased by 100% and 12% respectively compared to the Code Design model. Therefore, the Code Design model had the lowest and the Balance-25% and Symmetric Strength models had the highest dynamic seismic performance.
Ms Najmeh Mohammadi, Dr. Giti Forghani Tehrani, Dr. Afshin Qishlaqi,
Volume 16, Issue 4 (Winter 2022)
Abstract
Acid mine drainage (AMD) as the most important environmental issue in mining sites is considered a significant source of environmental pollution. AMD is typically produced by the oxidation of sulphide minerals, especially pyrite. The present study aims to investigate the acid production potential of the wastes of Mehmandoost coal washing plant located in NE Damghan. For this purpose, mineralogical, geochemical, and statistic tests were carried out on 7 representative coal washing waste samples. The obtained results show that although coal washing wastes are not enriched in Cu and Mn, they are moderately enriched in Ni and Co, significantly enriched in Cr, Sb and Zn, strongly enriched in Cd and As, and extremely enriched in Pb and Mo. The main mineral phases presented in the studied samples include quartz, muscovite, clinochlore, kaolinite, illite, montmorillonite, calcite and pyrite. In most of the studied samples, the pH and electrical conductivity (EC) of the saturated paste is <3 and > 2000 μm/cm, respectively. Moreover, in most samples the Net Neutralization Potential (NNP) is < -20. Also, in most of the samples, the Net Acid Production Potential (NAPP) is positive and the Neutralization Potential ratio (NPR) is < 3. The pH of Net Acid Formation (NAG pH) of these samples is < 4.5 and the ratio of Acid Neutralization Capacity to Maximum Acid Potential Acidity (ANC/MPA) is < 1. According to the results of static tests, there is a possibility of production of acidic drainage by the studied samples, therefore, taking suitable management measures to control acid production in the area is of crucial importance.
Dr. Davood Fereidooni, Dr. Sajeddin Mousavi, Dr. Esmaeil Najafi, Dr. Gholam Reza Khanlari,
Volume 16, Issue 4 (Winter 2022)
Abstract
Assessing and understanding the hydromorphological characteristics are necessary to understand the behavior of a river and its active processes. This is useful for understanding the erosion and sedimentation regime and changing the river path, for making correct engineering and human activities in the river's catchment area. The Gian River, with an average annual discharge of 2.3 m3/s, is one of the tributaries of the Gamasiab River in the Hamedan province. From a geological and hydrogeomorphological point of view, the Gian is a small river. It is fully compatible with the geological structures of the region. The calculation of the sinusoidal coefficient has shown that this river is a meandering river whose wavelength, the amplitude of the oscillation and the width of the meander belt are smaller in the mountainous area than in the plain area The gradient of the river bed is relatively low and it is classified as an erosion and sedimentation river in its different sections. The Gian River has a rocky bed in the mountainous part and an alluvial bed in the plain. The Gian River has a small catchment area, and, according to theGravelius' coefficient, its shape is almost elongated. The catchment elevation of the Gian River is between 1455 and 2700 with a weighted average of 1715.20 m.a.s.l. and its area decreases with the increase in the elevation. The concentration time of the catchment is 4.204 hours. The application of the data and results of the research can be very effective in land use planning, engineering and executive applications to predict river changes and protect engineering structures such as roads, bridges, coastal structures and railways, protect agricultural lands in the region and develop tourism.
Aylar Hosniyeh, Dr Rouzbeh Dabiri, Alireza Alizadeh Majdi, Elnaz Sabbagh,
Volume 16, Issue 4 (Winter 2022)
Abstract
Silty soils containing sodium content, known as salty silty soils, are classified as another type of problematic soil. When this type of soil comes into contact with water, it can swell and diverge, leading to settlement and deformation. Considering that a significant part of the Urmia Lake basin and the Tabriz plain consists of sodium-rich fine soils, the aim of the project is to improve the quality of the soils. Therefore, one of the main objectives of this study is to assess the sediments within the lake bed in order to reduce erosion and to evaluate the possibility of improving and stabilizing the sodium saline silty soils in the area using the geopolymerization technique. To achieve this, pumice material with pozzolanic properties was separately mixed with the soil under investigation at weight percentages of 3%, 5% and 7%, together with a calcium hydroxide solution as a catalyst at concentrations of 2%, 5% and 7%. The samples were then cured for one day. Laboratory tests, including compaction, uniaxial compressive strength, direct shear, and consolidation, were carried out to evaluate the geotechnical behavior of the improved soil. The results obtained indicate that the combination of 3% pumice with 2% calcium hydroxide increased the uniaxial compressive strength of the stabilized sample by 1.32 times after one day of curing. In addition, the mixture of 7% pumice with 2% calcium hydroxide significantly improved the internal friction angle by 20 times. Finally, the combination of 7% pumice with 2% calcium hydroxide reduced the value of free swelling potential by up to 86%.
Dr Seyed Yahya Mirzaee, Phd Student Zahra Chaghazardi, Dr Manouchehr Chitsazan, Dr Farshad Alijani,
Volume 17, Issue 1 (Spring 2023 2023)
Abstract
The Evan plain is located in the Khuzestan province in the southwest of Andimshek city. Groundwater is one of the available water resources for irrigation, drinking, and industry in this region. Due to the importance of examining the ground water quality of the Evan plain, hydrochemical parameters and nitrate pollution have been evaluated. Nitrate is one of the most widespread pollutants of ground water in the world. However, few studies have been conducted on this pollutant in the Evan plain. Therefore, to assess the quality of ground water in this area with emphasis on nitrate pollution, sampling was carried out in September of the water year (1400-1401) from 22 wells in this plain. During the sampling, field parameters (temperature, pH, EC), concentrations of major elements (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO32-, CO32-), and nitrate were measured. The results of the factor analysis demonstrated three influencing factors, namely EC, Na+, K+, Mg2+, Ca2+, Cl-, SO42- (as the first factor), pH and Hco32- (as the second factor), and NO3- (as the third factor), with a total of 89.72% having the most changes in the Evan plain aquifer. The dominant water type in the Evan plain is sulfate-calcite. Hierarchical clustering analysis shows the three clusters for the regionalization of nitrate data. In general, the changes in nitrate ion concentration in the groundwater of the Evan plain are affected by the size of the soil particles, the depth of the groundwater, and the utilization of chemical fertilizers in the area.
Dr Asghar Milan, Mehran Shafiei,
Volume 17, Issue 2 (Summer 2023)
Abstract
Calculating the volume of earthworks in mines is one of the challenging, costly, and time-consuming issues in the field. In mining projects, it is necessary to calculate the volume of excavation to estimate the volume of extraction in order to plan the sale of the produced products and to calculate the cost performance of the contractors. The calculation of excavation volumes presents many challenges, such as the selection of the best measurement tool and technique, the need to adjust maps produced in different time periods, the existence of inflation coefficients and the volume to weight conversion factor. Today, tools such as laser scanners, total stations and metric cameras are used to calculate earthwork volumes. However, they are expensive to use and require an experienced operator. Therefore, there is a need to investigate methods to calculate volumes in less time with acceptable accuracy. This research evaluated the use of smartphones for optimal volume estimation of earthworks. In this research, the image data obtained from the smartphone was processed with a technique based on structure from motion (SFM) and the results were used to create a digital terrain model to estimate the volume of earthworks. The calculated volume differences for the earthworks volume compared to ground methods for a soil mass and the studied excavation are 3.86% and 1.84% respectively, which shows that the method used in this research has the necessary accuracy to calculate earthworks volumes and considering the many advantages it has over traditional methods in terms of cost and time, it can replace them.
Somayeh Zarei Doudeji, Rahim Bagheri, Hadi Jafari,
Volume 17, Issue 2 (Summer 2023)
Abstract
The science of system dynamics is a management tool capable of simulating complex systems in water resources. In this research, the model of the dynamic system of multi-purpose consecutive Kardeneh-Sana dams located in Bushehr province has been simulated. The purpose of this modeling is to realize the different needs of the dam (drinking, environment and industrial agriculture) before its construction and also to investigate the effect of construction of the upstream dam on the supply of the downstream dam. The results were studied after calculating the annual and monthly percentage of volume and time supply of the different needs and source of supply, as well as considering two drinking water wells to provide drinking water in the months when the dam is not able to provide drinking water and the maximum The discharge of the current drinking water pipeline of the region was carried out. Six management scenarios were considered for modeling, and finally the sixth scenario was considered as the most optimal scenario. In order to evaluate the model, the simulated values were compared with the observed values of the water volume of Sana Dam. The results indicate that the volume supply of drinking, environment and industrial agriculture needs of Kardeneh Dam is 97.66, 96.59 and 82.76 respectively, and also the volume supply of environment and agriculture needs from Sana Dam is 100, 48 respectively. It is 83.0%, which is within the acceptable range of the Ministry of Energy. Based on this research, it was determined that by modeling based on model evaluation indicators including percentage of volume supply and percentage of time supply of different needs, it is easy to determine the effect of management and exploitation policies on the way of determining and allocating resources. Water observed and made the most optimal decision.
Professor Hamidreza Nassery, Koosha Tamimi, Dr Farshad Alijani, Dr Sadegh Tarigh Azali,
Volume 17, Issue 3 (Autumn 2023)
Abstract
The development of underground transportation activities in cities, such as tunnel boring, may exert short-term or long-term effects on the groundwater and springs of such areas. The construction of the tunnel of Tehran Metro Line 6 (TML6) through alluvium and carbonate rocks of Ali Spring has aroused concern due to the caused fluctuations in discharge and temporary dryness of the spring. The hydrochemical properties of the groundwater and catchment area were investigated to find a connection between the aquifers around the spring and determine the major aquifer feeding it. The estimated volume of water penetrated to the tunnel and the most greatly affected area by the water leakage into the tunnel was determined using analytical methods of water leakage into the tunnel and the DHI method. The statistics for precipitation with the changes in the discharge of the spring before and after the excavation of the metro tunnel were compared to evaluate the changes in the discharge of the spring with the precipitation in the area. The results showed that the metro tunnel excavation has dramatically affected the hydrological system of the area and discharge of the Ali Spring. Moreover, continuing the extraction may produce adverse effects on the discharge of other springs and wells and alter the flow system of the area temporarily or forever.
Amin Ahmadi, Gholamreza Mirzavand, Maryam Zebarjad,
Volume 17, Issue 3 (Autumn 2023)
Abstract
The zone of influence of the well is the area where the activity of the well changes the water level. The zone of influence is important in determining the protection zones; however, in this regard, reliable relationships have not yet been presented and their lack of relationship has not been confirmed; and this is due to the lack of accurate knowledge of the zone of influence in some aquifers. This study was carried out using the MODFLOW model to know the effect of aquifer physical parameters on the drawdown cone in an unconfined alluvial aquifer with a sloping water surface; and since no such research has been reported so far, the results are innovative. The results showed that although it is possible to ignore the effect of a well in parts of the aquifer due to measurement and presentation limitations, in practice the influence zone of each well will extend to the outer physical boundaries. It was found that two types of real and theoretical drawdown cones can be discussed in the influence zone and each should be analyzed separately. It was found that parameters such as hydraulic conductivity, saturation thickness, transmissivity, horizontal anisotropy, bed slope, and amount of recharge in sloping unconfined aquifers have a dual effect on the drawdown cone, and if their high values decrease the drawdown in short distances, they increase the drawdown in long distances. It was found that normal heterogeneity does not change much on the drawdown cone, and the reason is the opposite effects of hydraulic conductivity and specific yield on the drawdown value. It was found that hydraulic conductivity, horizontal anisotropy and specific yield have a strong effect, but vertical anisotropy and heterogeneity have a negligible effect on the drawdown cone.
Hossein Mohammadzadeh, Vahid Naseri Hesar, Hamid Ghalibaf Mohammadabadi,
Volume 17, Issue 4 (Winter 2023)
Abstract
Due to the complex hydrogeology of karst areas, the sealing of dams in such areas is more difficult, time-consuming and expensive, and the possibility of water leaksge is higher. After the dewatering of the Gharetikan dam and appearance of downstream springs and the leakage of water from the abutment of the Tirgan limestone formation, the possibility of karst development is considered to be the most important problem of this dam. In this article, the potential of karst development in the area and supports of the Gharetikan Dam has been studied by carrying out geological studies, structural geology and joint studies, geotechnical permeability and analysis hierarchy method (AHP).. The results show that about 14.6% of the Gharetikan dam area has a high potential for karst development. The area of Gharetikan dam area is affected by the Sarroud fault zone system, which has caused the collapse of the left side of the dam axis. The joint studies in the abutment of Gharetikan dam show three main types of joints. Two groups of joints are located at the intersection with the dam axis and the slope of the other group of joints is towards the dam basin. The investigating of Lugeon permeability tests in the dam construction shows that the highest permeability can be seen in the left abutment with turbulent flow, and then under the river bed with linear and turbulent flow, but there is no permeability in the right abutment. And the flow is mostly linear. According to the structural-conceptual model prepared from the location of the Gharetikan dam, to the location of the dam axis in the Sarroud fault system, and the amount opening and the slope direction of the joints in each station, it is expected that the amount of water leakage and escape and the possibility of karst development from the left side and the bed of the dam will be more than the right side of the dam.
Dr Seyed Yahya Mirzaee, Phd Student Roghayeh Amiri, Dr Manouchehr Chitsazan,
Volume 17, Issue 4 (Winter 2023)
Abstract
This study investigates the effects of climate change on the Khorramabad Central Plain aquifer. The climatic variables of temperature and precipitation were studied and downscale using GCM and LARS-WG models for a 45-year base period (October 1971 to September 2015). Temperature and precipitation values were then projected for a 30-year period (October 2024 to September 2054) under the climate scenarios SSP1.2.6, SSP2.4.5 and SSP5.8.5. The rainfall runoff simulation was carried out in the Khorramabad basin using the IHACRES model. The groundwater flow in the central plain of Khorramabad was calibrated using MODFLOW code for a period of 120 months (October 2010 to September 2020). This model was validated for a period of 36 months (October 2020 to September 2023). According to the results, the values of precipitation in the future period compared to the base period will decrease by 42.6, 47 and 61.9 mm in the scenarios SSP1.2.6, SSP2.4.5 and SSP5.8.5 respectively. The annual mean of minimum and maximum temperatures increases in all three scenarios. After calibration of the IHACRES model, NSE=0.74, RMSE=1.46 and R2=0.64 were obtained. According to the results, the predicted discharge of the Khorramabad River in the future period will increase by 2.38 m3.sec in the SSP1.2.6 scenario and decrease by 0.42 and 0.94 m3.sec in the SSP2.4.5 and SSP5.8.5 scenarios, respectively, compared to the base period. The average 30-year aquifer balance under the SSP1.2.6, SSP2.4.5 and SSP5.8.5 scenarios was 27494.5, -12335.3 and -41823.3 m3, respectively. The groundwater level of the Khorramabad Central Plain aquifer will decrease in the future period.
Prof. Mohammad Nakhaei, Dr. Amin Mohebbi Tafreshi, Dr. Tofigh Saadi,
Volume 17, Issue 4 (Winter 2023)
Abstract
A sharp drop in groundwater level as a result of indiscriminate extraction over a long period of time leads to the drying up of groundwater flows, which is called the phenomenon of groundwater drought. In this regard, this research aims to investigate the process of change and reduction of groundwater level, which is characterised by the phenomenon of groundwater drought. Based on this, the Groundwater Resource Index (GRI) was used to evaluate the drought condition of groundwater and analyse its spatial and temporal patterns based on groundwater level data of 21 observation wells between 1993 and 2019. ArcGIS software was used to create zone maps. The results of the research show that certain areas of the study area have experienced moderate to severe drought since 2001. In addition, the GRI zonation maps show that the southern and south-eastern regions of the aquifer have been more sensitive to drought than other parts of the aquifer during the defined period. The spatio-temporal pattern of groundwater drought in the aquifer shows that after a period of moderate drought from 2001 to 2003, the condition of the aquifer improved slightly, and generally stable conditions were established from 2001 to 2010, but since 2011, the occurrence of drought has intensified and the aquifer has been in severe to very severe drought conditions. These conditions highlight the need for careful attention and implementation of management measures. One of the study's recommendations is to use satellite data on groundwater levels to assess the progress of the drought, and compare it with the findings of this study.
Amin Ahmadi, Maryam Zebarjad, Ghoramreza Mirzavand,
Volume 18, Issue 1 (Spring 2024)
Abstract
The zone of influence is the area where water withdrawal from the well causes the water level to fall. The drawdown cone is a conical shape of the water level in the zone of influence, and it is necessary to know the effect of the factors influencing it. Previous studies have mainly investigated aquifers with horizontal water levels and less realistic conditions. The purpose of this study is to investigate the effect of well physical parameters on the drawdown cone in one of the unconfined aquifers with a sloping water surface. In this aquifer, a normal discharge well was simulated using the Modflow program and the effect of the target parameters was studied. The results showed that: the drawdown cone is symmetrical up to long pumping and relatively long distances; the zone of influence will eventually extend to the entire aquifer and significant drawdown will occur at long distances. A significant part of the drawdown in the well is recovered in the first moments of pump shutdown, but at long distances, the drawdown continues to increase for a long time. An inflection point can be extracted from the drawdown cone which represents the minimum drawdown that does not increase after the pump is stopped and can be introduced as a unique value. By increasing the flow several times, the depth of the cone increases, but the width of the cone increases only slightly. If the pump is turned on and off successively, the general shape of the cone does not depend on the nominal discharge of the well, but mainly on the average discharge of the aquifer. Relative infiltration increases the depth of the cone only near the well and has no significant effect on its shape further away.
Somayeh Zarei Doudeji, Rahim Bagheri, Hadi Jafari,
Volume 18, Issue 1 (Spring 2024)
Abstract
Groundwater resources in Iran are of particular importance due to the lack of surface water resources, lack of precipitation, high evaporation volume and recent droughts. The first step in identifying and exploiting groundwater resources is its quantitative and qualitative investigation. Neyriz watershed, located in the study area of Qatroiye desert, has 17 piezometers, whose groundwater level has been recorded monthly during the statistical period of more than 12 years. Investigations of the groundwater level and the map of the flow lines show the anomaly of the flow in the south and southwest part of the aquifer, which shows the direction of the groundwater flow contrary to the direction of the topography of the area. In this research, an attempt was made to investigate the cause of this anomaly based on the available information, including piezometer drilling logs, aquifer quality data, and national statistical data. Based on the qualitative information of the aquifer, the electrical conductivity and chlorine values of the groundwater increase in the direction of the topographic slope, which indicates the flow in the direction of the topographic slope. Qualitative charts of Piper, Schuler and Durov also confirm this issue. The level of groundwater in selected exploitation wells for qualitative sampling based on the information of the depth of groundwater in national statistics also indicates the flow in the direction of the topographic slope. Finally, a clay layer with a thickness of 10 to 30 meters was observed in the drilling log of the piezometers in the south and southwest of the aquifer. Examining all the results shows that the existing aquifer is probably a double-layered aquifer, where the flow direction in the upper layer is in the direction of the topographic slope and in the lower layer is against it, and the piezometers of the south and southwest parts penetrated the lower aquifer. In order to confirm the desired hypothesis, it is suggested to carry out geophysical studies in the area or to dig exploratory wells.
