Search Results (20)

This study examined groundwater dynamics under saline–alkali improvement measures in a 3.66 × 10⁷ m² study area in Wuyuan County, Hetao Irrigation District, where agricultural sustainability is constrained by soil salinization. This work investigated the spatiotemporal evolution patterns and influencing factors of the groundwater environment in the context of soil salinity–alkalinity improvement, as well as the impact of irrigation on the ionic characteristics of groundwater. Furthermore, based on this analysis, a groundwater numerical model and a prediction model for the study area were developed using Visual MODFLOW Flex 6.1 software to forecast the future groundwater levels in the study area and evaluate the effects of varying irrigation scenarios on these levels. The key findings are as follows: (1) The groundwater depth stabilized at 1.63 ± 0.15 m (0.4 m increase) post-improvement measures, maintaining equilibrium under current irrigation but increasing with reductions in water supply. The groundwater salinity increased by 0.59–1.2 g/L across the crop growth period. (2) Spring irrigation raised the groundwater total dissolved solids by 15.6%, as influenced by rock weathering (38.2%), evaporation (31.5%), and cation exchange (30.3%). (3) Maintaining current irrigation systems and planting structures could stabilize groundwater levels at 1.60–1.65 m over the next decade, confirming the sustainable hydrological effects of soil improvement measures. Reducing irrigation to 80% of the current water supply of the Yellow River enables groundwater level stabilization (2.05 ± 0.12 m burial depth) within 5–7 years. This approach decreases river water dependency by 20% while boosting crop water efficiency by 18.7% and reducing root zone salt stress by 32.4%. Full article

Heavy metal-organic pollutants compound pollution at industrial legacy sites and have caused damage to the ecological environment and human health during recent decades. In view of the difficulty and high cost of post-contamination remediation, it is worth studying, and practically applying, cutoff walls to reduce the spread of pollution in advance. In this study, field-scale studies were carried out at e-waste dismantling legacy sites in Taizhou, Zhejiang Province of China, through the process of site investigation, numerical simulation, and cutoff wall practical application. Firstly, the concentrations and spatial distributions of Pb, Cd and polychlorinated biphenyls (PCBs) and poly brominated diphenyl ethers (PBDEs) were identified in both soil and groundwater. Then, potential dispersal routes of key combined contaminants (Pb and PCBs) at the soil–groundwater interface were systematically studied through numerical simulation applying Visual MODFLOW-MT3DMS. One site was chosen to predict the barrier effect of differently sized cutoff walls based on the migration path of compound pollutants. A protocol for a cutoff wall (50 m length × 2 m width × 3 m height) was finally verified and applied at the real contaminated site for the blocking of compound pollutant diffusion. Further, the groundwater quality of the contaminated site was monitored consecutively for six months to ensure the durability and stability of barrier measures. All pollutant indicators, including for Pb and PCB complex pollutants, were reduced to below the national Grade IV groundwater standard value, achieving environmental standards at these polluted sites and providing possibilities for land reuse. In summary, this field-scale test provided new ideas for designing cutoff walls to block the diffusion of complex pollutants; it also laid a basis for the practical application of cutoff walls in pollution prevention and control of complex contaminated sites and for soil–groundwater environmental protection at industrial heritage sites. Full article

Mine water inflow is a significant safety concern in coal mine operations. Accurately predicting the volume of mine water inflow is vital for ensuring mine safety and environmental protection. This study focused on the Laohutai mining area in Liaoning, China, to reduce the reliance on hydrogeological parameters in the mine water inflow prediction process. An integrated approach combining grid search (GS) with the Seasonal Autoregressive Integrated Moving Average (SARIMA) and Long Short-Term Memory (LSTM) model was proposed, and its results were compared with Visual MODFLOW. The grid search was used to optimize the SARIMA model, modeling the linear component of nine years of water inflow data, with the remaining six months of data used for model validation. Subsequently, the prediction residuals from the SARIMA model were input into the LSTM model to capture the nonlinear features in the data and enhance the generalization capability and stability of the LSTM model by introducing Dropout, EarlyStopping, and the Adam optimizer. This model effectively handles long-term trends and seasonal fluctuations in the data while overcoming limitations in capturing periodicity and trends in complex time series data. The results indicated that the GC-SARIMA-LSTM model performs better than the Visual MODFLOW numerical simulation software in predicting mine water inflow. Therefore, without hydrogeological parameters, the GC-SARIMA-LSTM model can serve as an effective tool for short-term prediction, advancing the application of deep learning in coal mine water inflow forecasting and providing reliable technical support for mine water hazard prevention. Full article

It is an effective measure to prevent water damage in coal mines in order to construct drainage boreholes in water-filled aquifers of a working face roof. The hydrogeological parameters of the roof water-filled aquifer and the parameters of the drainage borehole are closely related to the underground drainage effect. Taking the 3085 working face of the Donghuantuo Mine in Kailuan as an example, the influence degree of hydrogeological parameters and hydrophobic borehole parameters on the amount of drainage water was analyzed using the generalized gray correlation degree. Based on Visual Modflow, the 3D groundwater visualization model was established and the dredging borehole was generalized into the pumping borehole. By changing the main influencing factors, the design optimization of the advanced hydrophobic borehole was discussed. The results showed that the aquifer thickness had a great influence on the amount of water discharged, and the influence degree of the sharp angle between the formation and the direction of drilling, the depth of the final hole, the azimuth angle of drilling, the dip angle of drilling, the elevation of the final hole and the elevation of the borehole on the amount of water discharged decreased successively. Based on the simulation calculation, it could be observed that the hydrophobic borehole should be placed in a position with a larger accumulated thickness of the aquifer to have a better effect of hydrophobic depressurization. Full article

Aiming to assess the groundwater nitrogen pollution problem in a typical section of the Wei River in China, the contribution of groundwater nitrogen pollution sources in the region was studied. Using Hydrus-1D to implement the simulation process of substituting points for surfaces, we calculated the volume and nitrogen concentration of the water leaching out from the bottom of the encompassing aeration zone. The results of the Hydrus-1D simulation were input as initial values into the nitrogen migration and transformation numerical model constructed using Visual MODFLOW to integrate the simulation calculations between the surface, the aeration zone, and the aquifer system. In addition, the contribution rates of different groundwater nitrogen pollution sources were calculated using the equilibrium formula combined with the groundwater nitrogen test results. The simulation results showed that the groundwater nitrogen in the southern part of the Wei River comes from two main sources: vertical infiltration and river recharge. Specifically, ammonia nitrogen vertical infiltration and river recharge contribute 95.82% and 4.18%, respectively; nitrite nitrogen vertical infiltration and river recharge contribute 92.41% and 7.59%; and nitrate nitrogen vertical infiltration and river recharge contribute 94.26% and 5.74%. According to the simulation results, an increase in the intensity of surface water pollution control is required in the study area. It is also necessary to control the use of nitrogen fertiliser on farmland in the study area and improve the utilisation rate of nitrogen fertiliser to reduce the nitrogen pollution loads from these sources. Full article

The fate of agriculture in Pakistan is predominantly concerned with excessive water mining threats to the subsurface water resources. The current study integrates the Visual MODFLOW-2000 application to estimate the water balance of an aquifer bounded by the Chenab River in the West and the Ravi River in the East, which covers an area of about 2.98 million hectares. An assimilated method of groundwater flow is employed to characterize the flow dynamics of the Rechna Doab aquifer. The Digital Elevation Model (DEM) produced by the Shuttle Radar Topography Mission (SRTM) and a mesh of discretized cell size (2500 m) were incorporated into the model design. The conceptual model of the alluvial aquifer involves trifold vertical boundaries (an initial fold thickness set up to 150 m). The model input parameters are precipitation, seepage through irrigation, return flow, recharge, hydraulic conductivity and evapotranspiration. Empirical relations are established (at the basin scale) for the discharge input of irrigation canals. Model results confirm that groundwater flow follows the topographic configuration of the study area (i.e., northeast to southwest), and the seepage from irrigating canals and rainfall appeared to be the main source of groundwater recharge among various resources. The zone budget study under steady state simulation showed that the total direct recharge to the aquifer is calculated as 522,910 acre foot. The simulated water balance of the studied aquifer reflects more fluctuations in river leakage. The predictive optimized model reflects an adaptation of canal lining and installation of additional tube wells that will minimize canal seepage by 70% and lead to the reclamation of 37,000 acres of water-logged land for normal cropping. Full article

Maringá, in southern Brazil, is undergoing a crisis with the alternation of dry and wet periods and floods caused by heavy rainfall along with the lack of infiltration of the stormwater. Due to a combination of these two opposite factors, the central lake of Ingá Park, which is an important urban park of the city, is suffering from water level reduction. This paper aims to verify if a sustainable drainage system design with infiltration wells can help recharge the surface aquifer. To this end, a stormwater drainage system simulation was conducted using SewerGEMS. Additionally, a calibrated shallow aquifer computational model was run in Visual Modflow Flex considering recharge wells to verify whether rainfall events impact the water levels of the surface aquifer. The results show that the sustainable intervention in a drainage system to increase stormwater infiltration has the potential to effectively recharge the shallow aquifers, while helping, at the same time, the drainage system, which is operating beyond design capacity, and the Ingá Park Lake. Thus, this study demonstrates that the sustainable design of drainage systems can help restore the springs inside the urban park. However, it is important to continuously monitor the wells’ heads and the hydrological variables. Also, for future studies, new models and simulations must be undertaken using the continuous monitoring data already available. Full article

Groundwater is an essential freshwater source because traditional sources of freshwater, such as rainfall and rivers, are unable to provide all residential, industrial, and agricultural demands. Groundwater is replenished by different sources: rivers, canals, drains, and precipitation. This research aims to apply numerical models for a real case study (Bahr El Baqar drain) in the Eastern Nile aquifer to monitor groundwater quality due to the use of wastewater from drains directly in irrigation due to the shortage of freshwater in this area. In addition, the effect of over-pumping from the aquifer is studied to show the extent of contaminants in groundwater. Moreover, a management strategy was achieved through mixing treated wastewater with freshwater to reduce the contamination of groundwater and overcome water shortage. Visual MODFLOW is used to simulate groundwater flow and contaminant transport into the Eastern Nile aquifer (ENDA), Egypt. In this study, three stages including 15 scenarios (five scenarios for each stage) were settled to achieve the study objectives. The first stage was carried out to investigate the impact of using untreated wastewater for irrigation due to the shortage of freshwater in this area. The results of this stage showed that increasing the use of untreated wastewater increased the contamination of the aquifer. The average COD concentrations in the five scenarios reached 23.73, 33.76, 36.49, 45.13, and 53.15 mg/L. The second stage was developed to evaluate the impact of over-pumping and using untreated wastewater for irrigation due population increase and a reduction of freshwater in the Nile Delta. The results revealed that over-pumping has increased the contamination of the aquifer and the average COD concentrations increased to 25.3, 33.34, 40.66, 48.6, and 54.17 mg/L. The third stage was applied to investigate the impact of mixing treated wastewater with freshwater for irrigation to support the freshwater quantity. The results of this stage led to enhanced water quality in the aquifer and the average COD concentrations decreased to 20.26, 23.13, 26.03, 30, and 32.83 mg/L. The results showed that mixing freshwater with treated wastewater has a good influence on water quality, can be safely used in irrigation and reduces the effects on farmers’ health and life. Full article

The present study focused on the development and application of two computer numerical models, namely, a seepage model developed using SEEP/W software and a groundwater model developed using Visual MODFLOW software. The seepage model was applied to a 38 km length of the tail reach of the Trimmu–Sidhnai (T-S) link canal passing through a severely waterlogged area of 32,000 ha, with a water table within 0–1.5 m from the ground surface; this was to quantify the canal seepage under the present condition (without any intervention) and with the interventions of a concrete lining of the complete prism of the T-S link canal and concrete side protection of the T-S link canal, with the canal bed unlined. The groundwater model evaluated the effectiveness of three waterlogging management interventions, which included: (i) the rehabilitation of the 43 existing drainage tube wells, (ii) the rehabilitation of the existing surface drains, and (iii) a combination of the rehabilitation of the 43 existing drainage tube wells and the rehabilitation of the existing surface drains. The seepage modeling revealed that the concrete lining intervention can reduce 50% of the seepage of the T-S link canal, whereas the concrete side protection intervention can reduce only 21% of the canal seepage. The groundwater modeling revealed that the waterlogging management intervention of the rehabilitation of the 43 drainage tube wells and surface drains can lower the groundwater level from 139.2 to 138.3 m (0.9 m drop), resulting in the mitigation of waterlogging in 45% (14,400 ha) of the severely waterlogged area. The present study recommends that complete concrete lining of the T-S link canal has a huge potential to reduce seepage from the canal, and the combination of the rehabilitation of the 43 drainage tube wells and surface drains also offers a great potential for controlling waterlogging. This intervention can also be considered to mitigate waterlogging from the severely waterlogged area. Cost-effectiveness analysis of the concrete lining of the T-S link canal, the rehabilitation of the 43 existing drainage tube wells, and the rehabilitation of the existing surface drains need to be performed for decision-making and selection of the most cost-effective intervention for implementation. A study needs to be conducted for the development and evaluation of economical and socio-technically feasible and acceptable preventive waterlogging management interventions, including the improved management of irrigation systems, improved irrigation management practices at the farm, improved conjunctive management of surface and groundwater, and improved management of drainage systems at the primary, secondary, and tertiary canal command levels. Full article

During dry seasons or years, the runoff processes from small rivers influence the safety of riverside groundwater source fields. Water source exploitation has a considerable effect on river runoff. In this study, the riverside source field of the Liuan River in the Linquan County, Anhui Province, was analyzed. The effect of mining on the ecological flow of the river under river runoff conditions in different typical dry years was quantified. This was undertaken using numerical simulations of the groundwater flow to provide guidance for the establishment of mining schemes for riverside source fields. In 95% of typical dry years, the water supply of small rivers is insufficient. The improved 7Q10 method used to calculate the ecological flow in different dry years revealed that mining water had little effect on the ecological flow. However, during the pumping process, the groundwater level of the water source area decreased greatly. The establishment of riverside source fields can aid in reducing excessive development and use of deep groundwater. The planning, construction, and implementation of the “Divert water from the Yangtze River to the Huaihe River” project can effectively reduce the economic losses that have occurred due to severe drought in the local area. Full article

This study presents a potential treatment method for contaminated groundwater from a waste heap in southern Poland. The method is based on the continuous monitoring of two parameters: pH and electrical conductivity (EC). Four years of historical monitoring data (2007–2010) were modeled using a Visual MODFLOW based numerical model of groundwater flow and migration of pollutants for low and high precipitation periods. Mapping the natural conditions in the numerical model allowed for the direction of contaminant migration in the aquifer to be identified. Groundwater treatment via injection of a nano zerovalent iron (nZVI) suspension into the aquifer was then designed; the target contaminant was Zn(II) because of its high concentrations and relatively high toxicity. Online monitoring for mining waste heaps is proposed to record sudden outflows of contaminants into the groundwater related to climate change and to take remedial action via nZVI injection. EC is the variable to be introduced into the contaminant migration model, which allows to determine the nZVI injection locations. As a result, the aquatic environment would be effectively and economically protected. The optimal use of nZVI, without intensively interfering with the environment, is ensured. This method is a convenient tool when making decisions to treat mining-impacted groundwater. Full article

During the cold dry season, a large amount of groundwater is pumped for water-curtain cultivation in agricultural fields mostly located near the four major rivers of South Korea. Several weirs, installed previously to secure sufficient water resources from these rivers, were opened in 2017 for restoring the riverine environment. Weir-controlled river level fluctuations have altered stream–aquifer interactions, leading to groundwater drawdown. In this study, changes in stream–aquifer interaction caused by seasonal pumping and weir opening were investigated, using Visual MODFLOW. Two indexes that considered the pump type and aquifer characteristics—the pumping available thickness (PAT) and aquifer productivity index (API)—were used to analyze the effects of weir opening on seasonal groundwater use. Our simulations indicated that weir opening had a large impact on seasonal groundwater use due to groundwater drawdown, especially with respect to centrifugal pumps located in low transmissivity areas where the API decreased after the weir was opened. The resulting decrease in groundwater pumping rates would lower the thermal effect of the water-curtain greenhouse process. This indicates that water supply alternatives are needed so that the weirs can be operated efficiently and field requirements can be met, while the deleterious effects on groundwater are avoided. Full article

Recently, groundwater resources in Egypt have become one of the important sources to meet human needs and activities, especially in coastal areas such as the western area of Port Said, where seawater desalination cannot be used due to the problem of oil spill and the reliance upon groundwater resources. Thus, the purpose of the study is the sustainable management of the groundwater resources in the coastal aquifer entailing groundwater abstraction. In this regard, the Visual MODFLOW and SEAWAT codes were used to simulate groundwater flow and seawater intrusion in the study area for 50 years (from 2018 to 2068) to predict the drawdown, as well as the salinity distribution due to the pumping of the wells on the groundwater coastal aquifer based on field investigation data and numerical modelling. Different well scenarios were used, such as the change in well abstraction rate, the different numbers of abstraction wells, the spacing between the abstraction wells and the change in screen depth in abstraction. The recommended scenarios were selected after comparing the predicted drawdown and salinity results for each scenario to minimize the seawater intrusion and preserve these resources from degradation. Full article

Freshwater resources on small coral islands mainly exist in the form of freshwater lenses. The freshwater lens is highly vulnerable to salinization due to natural recharge variations and urbanization construction. However, it is unclear how a freshwater lens evolves under the influence of urbanization construction and which factors control its evolution. Based on the hydrogeological data of a small coral island in China, a corresponding 3D numerical model was established by the Visual MODFLOW software to investigate the formation and evolution of freshwater lenses under natural conditions. Thereby, the island reclamation scenario and impermeable surface scenario were set up and the changes in morphology and volume of the freshwater lens were analyzed. The results show the following: (1) After island reclamation and island building, the freshwater lens would reach a stable state after 25 years and the freshwater lens would also appear in the newly added part of the island with a thickness of 9.5 m, while the volume of the total freshwater lens would increase to 1.22 times that of the original island. (2) When the impermeable surface is built at different positions of the island, the reduction in the volume of the freshwater lens, in the order from large to small, is Scenario B (northeast side), Scenario A (southwest side) and Scenario C (central); with the increase in the impermeable surface area, the volume of the freshwater lens would gradually decrease and the volume of the freshwater lens would decrease by more than 50% with the impermeable surface exceeding 30% of the island area. The study has important implications for the conservation and rational development of subsurface freshwater resources on islands. Full article

The Juksan weir, installed in the Yeongsan river in South Korea from 2010 to 2012, has secured sustainable water resources and helped control flooding. However, low river flow velocities due to the weir have deteriorated the quality of the river water. For natural river restoration, the water gate was opened in 2017. In this study, the three-dimensional finite difference model Visual MODFLOW was used to analyze the effects of gate opening on stream–aquifer interactions. A conceptual model was developed to simulate the stream–aquifer dynamics caused by the operation of the water gate at the Juksan weir. Groundwater data were also analyzed to determine the impacts of weir operations on groundwater quality. Our results indicate that a lower river level due to the weir opening changed the groundwater flow, which then affected the water balance. The change in groundwater flow increased the variability of the groundwater quality which had homogenized because of induced recharge after the construction of the weir. This could affect groundwater use in agricultural areas near the weir. Therefore, further groundwater monitoring and hydrodynamic analyses are required to anticipate and address any potential issues. Full article