مجله هیدروژیولوژی
سال هفتم شماره 1 (تابستان 1401)

One of the main objectives of the agricultural sector in arid and semi-arid regions is to improve soil moisture conservation and water productivity. Evaporation from soil surface is non-beneficial losses in irrigation. Mulching is one of the most important agricultural managements in maintaining soil moisture and improving the physical environment of the soil. The use of mulch outside the growing season prevents the salinity of the topsoil. The purpose of this study was to investigate the effect of plant mulch on solute transfer, soil moisture, temperature and salinity outside the growing season, which using two laboratory lysimeters with a length of (1 m), a width of (0.5 m) and a height of (1 m) was investigated. During the 122-day simulation period, moisture and salinity values from 5 depths of soil profiles (50-40-30-20-10 cm) were measured. To compare the means of each treatment with each other, t-test was used in two software models, HYDRUS-2D and AquaCrop. RMSE, MBE, MAE and R2 statistical indexes were used to evaluate each model. The results show that the HYDRUS-2D model has a good ability to model moisture at depths of 10 to 40 cm, but for depths of 0 to 10 and 40 to 50 cm has not performed well in the simulation. Also, the results of AquaCrop model show that this model does not have a good ability to model moisture at depths and HYDRUS-2D model compared to AquaCrop model has the ability to better estimate and more acceptable relative accuracy of moisture at depths of 10 to 40 cm for simulation of solute transportation.This model does not have a good ability to model moisture at depths performed and HYDRUS-2D model compared to AquaCrop model has the ability to better estimate and more acceptable relative accuracy of moisture at depths of 10 to 40 cm for simulation

A large number of aquifers in different parts of the country are suffering from deduction of storage. This occurrence is due to proliferation demand for water, exploitation wells’ increase, reduction in precipitation and inappropriate spatial and temporal rainfall distribution. The alluvial Baghmalek aquifer with 49.93 km2 is one of the promising groundwater storages in Khuzestan, where supplies water for agriculture as well as other activities in the area. In this study quantity and quality aspects of the Baghmalek aquifer was assessed for a period of ten years (1386 – 1396), using statistics and geostatistics methods. To assess rainfall amount changes and its effect on groundwater within the statistical period, Standard Precipitation Index (SPI) and was taken into account. The unit hydrograph, groundwater table map and water table rising and descending map were prepared. The results indicated that on average the water table drop was -13.79 m in ten years period, but the outstanding fall (19 m) observed in the east and central parts of the area around piezometers. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) for qualitative data in the 2007-2017 period showed that the wells in the region are divided into three groups and electrical conductivity has the highest correlation with sulfate and calcium. Also, the principal component analysis states that there are two main factors in the region, that the first factor includes 60.12% of the changes, and in order of importance are: EC, SO4, Ca, K, Cl, Mg, Na, and the second factor that causes 15.15% of the changes, just includes HCO3.

The aim of the present study is regionalization of groundwater observation wells of Khoy plain into distinct clusters based on quality of water using the K-Means method. The recorded data of fourteen groundwater quality parameters including the Total Cations, Total Anions, Electrical Conductivity (EC), pH, Total Dissolved Solids (TDS), Sodium Absorption Ratio (SAR), Total Hardness (TH), Sodium percent (%Na), Magnesium (Mg2+), Calcium (Ca2+), Sodium(Na), Sulfate (SO42-), Chloride (Cl-), Bicarbonate ) were used. These data gathered for the 26 observation wells in the time period of 2001-2003. The optimum number of clusters was found by optimization method in K-means clustering algorithm assuming to be between two and five. In order to determine the groundwater quality to use in agricultural and drinking purposes the Wilcox diagram was used. The results showed that groundwater of Khoy plain can be classified into the four distinct classes. The first class covers an area equal to 214.3 km² (51.14 % of the total area of the plains), which has very favorable to use in agriculture and drinking use. The second region covers an area of 50.1 square kilometers (11.95 %) and the third region’s area was 52.7 km² (12.57 %), respectively. The third region has poor quality water and area of this region is equal to 9.101 km² (24.31%). The high values of EC and SAR were found in the third cluster, which led to groundwater quality to be poor. In general, it can be concluded that more than the 50 percent of the Khoy plain’s groundwater had desirable chemical quality. It is recommended to protect groundwater in Khoy plain from pollution risk and overexploitation. For sustainable use of groundwater, it is recommended to protect groundwater by prohibiting agriculturalists and other users from overexploitation.

Hydraulic conductivity and Specific storage are known as the most important hydraulic characteristics of aquifers. Recently, due to software advances, the use of numerical models in the operation of groundwater aquifers has expanded. Modeling is one of the best tools for studying and simulating the state of water resources. One of the advantages of modeling is the simultaneous determination of several parameters such as hydraulic head, flow path and etc. Likewise, via modeling, it is possible to simulate the reaction of the basin against changes such as natural or artificial recharge and the amount of pumping, and by applying appropriate solutions, determine the best performance of the system then use it to manage the basin. In the present study, MODFLOW numerical model and GMS user interface were utilized to simulate and calibrate the model. Accordingly, the hydrodynamic properties of the Shabestar plain aquifer were evaluated regionally. As a result, the RMSE values of hydraulic head for the steady-state and non-steady-state models were 0.59 (m) and 0.95 (m), respectively. The obtained results demonstrated that the more heterogeneous the aquifer, the more diverse the hydrodynamic coefficients will be, and this variation does not follow a specific trend due to the existence of geological formations, the density and the porosity of the formations.

Today, construction of dams to collect and store river water for different consumption purposes including drinking, agriculture, and industry is inevitable. Nevertheless, dams are colossal structures that pose potential dangers to their downstream community and their failure can be catastrophic. Dynamic analysis of concrete dams is more complex than that of conventional structures due to the presence of a reservoir. This complexity mainly results from the dam-reservoir interactions in seismic conditions. In this study, the seismic response of concrete gravity dams was investigated using Abaqus finite element software in different conditions of full, half-full, and empty reservoir. To this end, Koyna concrete gravity dam with specific geometric and physical characteristics was analyzed by applying Kobe earthquake records. The results from finite element analysis showed that the values ​​of the main stresses in different modes of analysis were considerably significant. Most of these stresses occurred at the site of the downstream slope change (level of 66.5 m), thus causing stress concentration in this area. Furthermore, according to the results, upon increasing the reservoir level, the amount and intensity of displacement fluctuations would increase, mainly due to the dam-reservoir interactions and effect of fluctuations in the hydrodynamic pressure of the reservoir in the time curve of the displacement in the crown of dam. In general, in case the reservoir is full, the levels of stress and displacement would be higher than those in other modes.

Permeability is one of the parameters affecting water flow in porous environments such as rock and soil mass and is of special importance in geotechnical studies, e.g., the location of important structures such as urban trains. Accordingly, determination of permeability is one of the main goals in geotechnical studies. Also, it is an important parameter in solving geotechnical problems such as seepage, settlement measurement, stability analysis, etc. Due to fact that direct methods (field and laboratory) of measuring permeability are expensive, highly specialized, time-consuming and unreliable, and due to the nonlinear behavior and heterogeneous and anisotropic conditions in hydrogeological environments which cause inherent uncertainty in the methods of direct measurement of this parameter, various artificial intelligence methods which work more accurately than the above methods  have recently been proposed  to compensate for some of these shortcomings. In this study, two individual artificial intelligence methods including Least-Squares Support Vector Machine (LSSVM) and Wavelet-Artificial Neural Network (WANN) were used on lines 1 and 2 of Tabriz Urban Train to predict hydraulic conductivity based on grain size data; then the results of these two individual models were combined by an Artificial Neural Network (ANN) and improved the results under the name of Supervised Intelligent Committee Machine (SICM). Comparison of test step results of the three models presented in this study showed that all the three models had a relatively good performance in predicting hydraulic conductivity, but SICM model with Root Mean Squared Error (RMSE)= 0.000161 cm/sec and Determination Coefficient (R2)= 0.83 provided better results than the individual models.

Understanding the relation between the rock geomechanical characters and its cement take is very important to estimate the cost of the dam and grout curtain constructions. Most of studied relations belong to limestone since dams are mainly located at karst terrains. A positive relation between cement grout absorption and the permeability of limestone is reported by many researchers. Roudbal Dam, with a reservoir capacity of 82 million cubic meters, is located in the Fars Province, SW Iran. The dam site is mainly consisted of radiolarite and limestone. In this study an attempt has been made to determine the relation between the cement consumption, rock quality and rock permeability of these geological units. Considering the rock quality index, limestone showed better quality than radiolarite. Based on the results of the water pressure test, limestone was more permeable than radiolarite. By analyzing the cement take values, it was detected that most of the sections with high consumption were located in the limestone. The cement take values only showed a well positive correlation with rock permeability. A correlation of 0.87 indicates a much stronger relation between cement take and permeability in limestone than correlation of 0.43 measuring the relation between these parameters in radiolarite. The results of this study showed that in sites with different lithology, estimation of cement consumption based on the results of Logan test and the rock quality index requires more accuracy and attention. By separating the data obtained from drilling in different rock units and performing calculations separately, the estimation error can be greatly reduced.

Aquifer transmissivity is one of the important parameters for groundwater quantitative and qualitative studies and modeling. Due to the limited number of pumping tests or the ambiguity in the accuracy of the measured values in some places, it is necessary to estimate the transmissibility value using the available information. In this research, the values of this parameter are determined using different interpolation methods including Inverse Distance Weighted (IDW), ordinary kriging (by use of circular, exponential, Gaussian and spherical variogram), universal kriging (include linear and quadratic trend), spline (regularized and tension) and trend (include linear and logistic regression) Therefore, here, the transmissivity coefficient of the Damaneh-Daran aquifer, as a case study, is determined and the results are presented and compared. Comparison of the results shows that performing interpolation with Regularized Spline leads to the lowest accuracy and using Ordinary Kriging method in power mode leads to the highest computational accuracy (with 20.11% relative error). However, this method is not effective for interpolating points located in the boundary areas of the study state. In contrast, the IDW method with a maximum of 21.36% relative error can be used for interpolation in all parts of the region. Finally, in order to evaluate the performance of this method, the Damaneh-Daran aquifer is simulated based on the results of IDW method as initial values and using GMS software. By comparing the results obtained from calibration of the aquifer with values obtained from interpolation, the maximum relative error value is 22.22% and the average relative error at the aquifer level is 15.69%. Also, with a significant reduction in the number of iterations in the calibration phase of the model, the computational cost is significantly reduced.

Currently, uncontrolled extraction of groundwater resources has led to a decline in the water table of aquifers, especially in arid and semi-arid regions. Today, one of the ways to improve the water table of aquifers is the use of artificial recharge plans. This study has been done to numerically simulate the artificial recharge plan of Birjand plain through the construction of injection wells using the numerical model of Isogeometric analysis. In this regard, first a standard example with two wells with discharges of 1142.85 and 1428.57 m3/day was used to simulate the water table for 210 days. After evaluating the accuracy of the model, the water table before injection was simulated based on the existing conditions and after injection using 20 injection wells with a constant flow of 7638.44 m3/day in 12 time steps in the unconfined aquifer of Birjand plain. Comparison of the results of Isogeometric analysis and analytical solution model in standard aquifer with estimated evaluation criteria equal to ME=-0.0096, MAE=0.0111 and RMSE=0.0146 and also in Birjand plain unconfined aquifer with evaluation criteria of ME=-0.033, MAE=0.372 and RMSE=0.229 shows the model accuracy in simulating the water table before injection. Also, after running the numerical code of the injection wells construction plan, by interpolating the water table obtained at the control points in the location of 10 existing observation wells, the results at the end of the simulation period shows increasing the water table maximum 60.53 cm in observation well number 2 and minimum 1.25 cm in observation well number 9.

Cement grouting is the most common methods using for improving, treatment and sealing the foundations of structures and construction sites of dam projects. In this method, through injecting the cement grout by pressure, joints and fractures of rock mass subjected to filling and as a result, the geomechanical characteristics of the rock mass improving due to integrity and reducing of permeability. The key to success in using this approach is to correctly evaluate the grout-ability of rock mass and, consequently, to determine the mixing plan and designing of grouting parameters. Peygham-Chay Reservoir Dam is an embankment dam with a clay core and a height of 46 meters from the riverbed, which is under construction in East Azerbaijan province, 15 km southwest of the Kaleybar city. The bedrock of the dam site is basalt, which is covered by alluvial deposits in the riverbed and the left abutment. The bedrock is fractured due to 3 main joints and a number of sub-joints and faults. Based on the results of Lugeon tests in the construction site along to the dam axis, in most test sections, the permeability is less than 3 Lugeon. The rock mass quality index (RQD) in the study site in 75% of sections is less than 25% and in only 1% of sections is more than 75%. Investigation of the relationship between RQD and Lugeon values shows that most sections with low to high RQD have low permeability and there is no logical relationship between these two parameters. In different RQD, the cement take is low that indicates the presence of rock mass with low to high degree of jointing with filled and/or with low aperture as well as very low continuity. The study of the relationship between the cement take and different classes of secondary permeability index (SPI) shows that there is no logical relationship between this parameters in the study site. Based on the obtained results, the rock mass forming the study site is low grout-ability.

The phenomenon of land subsidence, which is affected by human activities and various geological and hydrogeological parameters, is occurring in different parts of Iran. Land subsidence susceptibility mapping is a necessary prerequisite for land subsidence management. Proper assessment of land subsidence requires the determination of parameters affecting land subsidence to discover the spatial relationships between them and land subsidence. For this purpose, first, according to the land site subsidence, eight parameters affecting the subsidence in the Damaneh-Daran plain, two models were prepared. In the first model, eight parameters including annual groundwater level drawdown, aquifer medium, land use, pumping volume, aquifer thickness, net charge, distance from fault and topography called WALPSRFT based on weighting parameters and the second model based on optimization and compatibility of eight effective layers in subsidence, Was prepared by AHP-Fuzzy2 method and the final map of land subsidence vulnerability was obtained by combining layers in ArcGIS. Radar images and a Radar Interferometer (InSAR) were used to validate the models. The results show that both maps show a good correlation with radar data, and the map prepared by the hierarchical-fuzzy method shows the highest correlation with real radar data and subsidence in the plain. It separates in more detail on the whole surface of the plain. According to this model, most areas of the plain, especially the eastern part, are subject to subsidence, and management programs should be considered to control subsidence.

Exploitation of karst water resources has become very important due to supply and demand tensions and water shortage problems. Utilization of these resources without management and planning causes severe pollution. One of the important tools for this issue is the use of vulnerability indicators and determining the degree of risk of exploiting it. In this study, the dependence of spring appearance as the output of karst catchment and its catchment is investigated by combining vulnerability indicators. VESPA is one of the most important methods to calculate spring’s vulnerability using effective parameters such as salinity, discharge and water temperature. Moreover, in this study we applied EPIK method to assess vulnerability of karst watershed. Then, by ranking the effective parameters and combining it with the vulnerability index, it determines the level of risk in the basin. Accordingly, Perikdan and Sarabtaveh springs are in a very high class in terms of vulnerability with VESPA index and have a high correlation with EPIK index in assessing the vulnerability of the catchment basin. After determining the vulnerability, the risk of exploitation was determined by ranking the slope parameters, geological formations, natural features and land use. The results showed that the highest risk rate of 74% is located in the southern parts of the region. This area has a large number of sinkholes and permeable karst formations. By combining the risk map and vulnerability index, the risk of the basin was assessed, which showed that about 90% of the basin is in medium and low risk.