Proposing the Optimum Withdrawing Scenarios to Provide the Western Coastal Area of Port Said, Egypt, with Sufficient Groundwater with Less Salinity

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.

Impact of Island Urbanization on Freshwater Lenses: A Case Study on a Small Coral Island

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.

Application of Visual MODFLOW to the Analysis of Boundary Conditions for a Phreatic Porous Aquifer Using Limited Available Information: A Case Study

The increasing water demand, especially in developing regions, continuously puts pressure on groundwater resources both quantitatively and qualitatively. Hydrogeological modeling is a tool used in planning and management of groundwater resources. The factors that interfere in groundwater flow dynamics can be determined by developing a conceptual model and they can be validated via a numerical model. The objective of the manuscript is the hydrogeological groundwater flow modeling of the phreatic porous aquifer of the Ribeirão Candidópolis catchment in the Itabira municipality, State of Minas Gerais (Brazil). The software used in this study is GMS: MODFLOW, which enabled a steady state flow regime modeling by means of the Finite Difference Method (FDM) and the parameters calibration from a semi-transient approach. To assess the performance of the model, the Mean Error (ME), the Mean Absolute Error (MAE), and the Root Mean Square Error (RMSE) were calculated. The results proved to be compatible with the values observed in the field. After several adjustments of the boundary conditions, a Normalized Root Mean Square (NRMS) of 9.648% and a correlation coefficient of 0.993 were obtained. Despite the economic importance of the study area, studies made available on groundwater flow behavior are rare. The results obtained via modeling are in accordance with the data observed in the field and consequently our model can be used in the study of water level changes.

Changes in Stream–Aquifer Interactions Due to Gate Opening of the Juksan Weir in Korea

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.

Delineation of Lithological Formation in Bukit Merah, Semanggol, Perak Using Groundwater Modelling Software

The knowledge of lithological formation is important to determine the potential aquifer for water resources management. This study aims to delineate the lithological formation of Bukit Merah, Semanggol using geological data. The preparation of lithological formation in the study was based on several factors such as electrical resistivity survey data, available well lithologies, geological map, and geological-related studies in the study area. The Electrical Resistivity Tomography (ERT) profile produced from the resistivity survey was interpreted based on previous studies to determine the subsurface materials on the location. The estimation of soil lithology for the remaining wells was done to generate the overall subsoil pattern in the study area. A total of 15 types of soil were classified to represent the actual lithology in the study area. The simplification of the actual lithology was carried out based on rocks and soils group. The elevation of the ground surface and each soil layer were imported into Visual MODFLOW software, then the interpolation of elevation points was done. Two interpolators; Kriging and Natural Neighbouring were used to generate ground surface and model layers similar to the topography in the study area. As a result, it has been identified that the study areas consist of 4 main layers of lithological formation which are unconsolidated deposit, sedimentary, metamorphic, and granite. The upper layer is dominated by unconsolidated with a maximum thickness of about 150 m in the coastal area. Hence, it is concluded that the unconsolidated deposit layer in Bukit Merah is highly potential with groundwater resources in the alluvium aquifer at the upper layer which has the potential to be developed for purpose of irrigation in a paddy field in the Kerian area.

Interacción entre la presa de relaves y el acuífero de la microcuenca del río Yuracyacu en la Región La Libertad del Perú

La interacción entre una presa de relaves y el acuífero de una microcuenca puede originar una probable ruta de los contaminantes hacia las aguas subterráneas, perjudicando el consumo doméstico y uso en la actividad agropecuaria. Es por ello, el requerimiento de conocer el tiempo del desplazamiento del contaminante en los acuíferos para ser detectados a tiempo y evitar su propagación. El estudio tiene como propósito desarrollar un modelo de simulación del transporte contaminante de un depósito de relaves hacia las aguas subterráneas de la microcuenca Yuracyacu para implementar medidas de prevención y mitigación ambiental. En esta investigación se contempla trabajos de campo y gabinete para obtener información hidráulica y química en la relavera y acuífero, asimismo diseño de modelo conceptual y transporte de contaminante de las aguas subterráneas, el cual se utilizó el software Visual ModFlow 2011.1 que resuelve ecuaciones de diferencias finitas para determinar el flujo del agua en medio poroso. El modelo de la simulación demostró que el transporte contaminante se detectaría en el pozo OBS-1 a los 150 días, en el OBS-2 a los 750 días, y en el OBS-3 llegaría a los 1450 días, por lo que se requiere aplicar medidas preventivas para evitar la ocurrencia y expansión del contaminante, así como también realizar vigilancia de la calidad de agua subterránea y continuar aplicando modelos de simulación de transportes contaminantes en acuíferos.

PEMODELAN ALIRAN AIRTANAH UNTUK SISTEM MANJEMEN DAN PEMBANGUNAN DI KAWASAN PERKOTAAN KABUPATEN MAJENE, PROVINSI SULAWESI BARAT

Model air tanah yang digambarkan komputer merupakan sebuah representasi dari keadaan sebenarnya yang mewakilinya di lapangan, sehingga dapat berfungsi sebagai monitoring dan perkiraan suatu sistem aliran air tanah di masa depan. Tujuan dari penelitian ini adalah pemodelan aliran air tanah yang dapat mewakili kondisi sebenarnya yang terjadi di kawasan perkotaan Kabupaten Majene. Pemodelan dilakukan dengan cara numerik menggunakan Visual Modflow. Data masukan yang dibutuhkan adalah : korelasi data logbor/geolistrik, batas (boundary) lokasi penelitian yang akan dimodelkan yaitu river boundary, pengukuran serta pengamatan kondisi sungai sebagai river boundary, data imbuhan air tanah (infiltrasi) diperoleh dengan menggunakan neraca air tanah dari olahan data curah hujan dan suhu udara, pengukuran tinggi muka air tanah sebagai penentuan alat validasi model untuk mendekati kondisi nyata di lapangan. Hasil dari penelitian ini berupa model aliran air tanah yang dapat digunakan untuk sistem manajemen air tanah sebagai alat pengambilan keputusan bagi pihak perencana proyek dan lembaga pemerintah dalam memprediksi perubahan sistem aliran air tanah, penentuan lokasi pembangunan dan dapat sebagai monitoring intrusi air laut di masa depan sebagai perkotaan yang berada di pinggir pantai.