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    Hydrogeological Model for Groundwater Prediction in the Shennan Mining Area, China
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    Keywords:
    Drawdown (hydrology)
    Bedrock
    Groundwater model
    Cone of depression
    A Sand Tank Groundwater Model is a tabletop physical model constructed of plexiglass and filled with sand that is typically used to illustrate how groundwater water flows through an aquifer, how water wells work, and the effects of contaminants introduced into an aquifer. Mathematically groundwater flow through an aquifer can be modeled with the heat equation. We will show how a Sand Tank Groundwater Model can be used to simulate groundwater flow through an aquifer with a no flow boundary condition.
    Groundwater model
    Groundwater discharge
    Aquifer test
    Cone of depression
    Groundwater flow equation
    Citations (0)
    Groundwater model for understanding and predicting hydraulics and contaminant transport in aquifer make assumptions about the distribution and hydraulic properties of geologic features that may not always apply to karst aquifers. In this study, a finite difference groundwater model (MODFLOW-NWT) was applied to construct an equivalent single layer two-dimensional mathematical model of the Ryukyu limestone aquifer, which is located a southern part of Okinawa main islands. In order to handle problems at regional scale groundwater model in the aquifer, automated parameter estimation method (PEST) was used in this model. Groundwater level measurements collected in 1994 were used to calibrate a steady state model of the study area. This study shows the ability of MODFLOW-NWT and PEST to simulate regional groundwater flow in highly karstified aquifer such as Ryukyu limestone aquifer, which is important for water resource and groundwater management in the area.
    MODFLOW
    Groundwater model
    Aquifer test
    Cone of depression
    Specific storage
    Citations (5)
    Abstract The purpose of this study is to establish a 3D groundwater flow modelling for evaluating groundwater resources of the North China Plain. First, the North China Plain was divided into three aquifers vertically through a characterization of hydrogeological conditions. Groundwater model software GMS was used for modeling to divide the area of simulation into a regular network of 164 rows and 148 lines. This model was verified through fitting of the observed and the simulated groundwater flow Gelds at deep and shallow layers and comparison between the observed and simulated hydrographs at 64 typical observation wells. Furthermore, water budget analysis was also performed during the simulation period (2002–2003). Results of the established groundwater flow model showed that the average annual groundwater recharge of the North China Plain during 1991 to 2003 was 256.68×10 8 m 3 /yr with safe yield of groundwater resources up to 213.49×10 8 m 3 /yr, in which safe yield of shallow groundwater and that of deep groundwater was up to 191.65×10 8 m 3 /yr and 22.64×10 8 m 3 /yr respectively. Finally, this model was integrated with proposal for groundwater withdrawal in the study area after commencement of water supply by South‐North Water Transfer Project, aiming to predict the changing trend of groundwater regime. As indicated by prediction results, South‐North Water Transfer Project, which is favorable for effective control of expansion and intensification of existing depression cone, would play a positive role in alleviation of short supply of groundwater in the North China Plain as well as maintenance and protection of groundwater.
    Groundwater model
    Cone of depression
    Depression-focused recharge
    Groundwater discharge
    Citations (45)
    The Eocene aquifer is one of the major groundwater aquifers in Palestine. It is located in the northeastern part of the West Bank covering areas of both Jenin and Nablus districts. The development of the groundwater within the Eocene aquifer is very essential for the Palestinian water supply. This paper simulates for groundwater flow in the Eocene aquifer using MODFLOW as a strong available groundwater model. The groundwater budget, flow computation, and flow path-lines were estimated and calibrated. Groundwater balance has been evaluated. The Modeling results show that a minimum initial level of 340 m above sea level should be applied to model the hydraulics of the aquifer correctly. The recharge and hydraulic conductivity are the most sensitive model parameters. The hydraulic conductivity in some areas has proved to be double than assumed by other literatures. More reasonable recharge coefficients in comparison to other literatures have been obtained. Groundwater balance indicated that the water budget of the Eocene aquifer totals about 72 MCM/yr. The modeling has indicated reasonable matching between the observed and modeled groundwater levels and spring flows. The flow direction within the aquifer is from the south to north and northeast. The Faria spring system located to the southeast is the major sink within the aquifer. It attracts most of the particle tracking lines due to its high discharge rates. It is recommended to monitor the existing wells and springs permanently. It is also recommended to assess the effect of the faults and fractures on the hydraulic conductivity. يعد الخزان الجوفي الأيوسيني من أهم الخزانات الجوفية في الحوض الشمالي الشرقي في الضفة الغربية من فلسطين، وهو من أهم مصادر المياه الجوفية العذبة في منطقتي نابلس وجنين. وقد أجريت عدة دراسات دعت إلى تطوير مصادر المياه الجوفية ضمن هذا الحوض، ومن هنا فان هذه الورقة تمثل ضرورة عمل نموذج رياضي لدراسة الخزان الجوفي الأيوسيني. تم استخدام برنامج MODFLOW وذلك لتوفره وسهولة التعامل معه، إذ تم تقييم كمية المياه التي يعطيها الخزان سنوياً والميزانية المائية له وكذلك تحديد اتجاهات حركة المياه الجوفية في داخل الخزان الجوفي. أشارت النتائج إلى أن النموذج لا يعمل إلا على مستوى هيدروليكي ابتدائي للمياه الجوفية لا يقل عن 340م فوق سطح البحر. وتم حساب حساسية النموذج لعاملي التغذية والنفاذية إذ تبين أنهما أكثر تأثيراً على النموذج للخزان الجوفي الأيوسيني، كما تم معايرة النموذج لكل من مستوى المياه الجوفية وتدفق الينابيع. القيم الابتدائية للنفاذية ارتفعت في بعض المناطق إلى ضعفي تلك الواردة في دراسات أخرى وذلك بسبب إهمال تأثير الفوالق (faults) والإنكسارات (fractures) والكرسته (karstification) في الصخور الموجودة في منطقة الدراسة، كما أن الدراسة أعطت قيماً مقبولة لمعاملات التغذية. بالنسبة للموازنة المائية المتجددة للخزان الجوفي الايوسيني فقد تبين أنها 72 مليون متر مكعب سنوياً. أظهر النموذج تطابق بين مستويات المياه وتدفق الينابيع المقروءة والمحسوبة وتبين كذلك أن خطوط التدفق والمياه الجوفية تتجمع باتجاه الشمال والشمال الشرقي للحوض، وأن خطوط التدفق تتكاثف باتجاه منطقة نبع الفارعة الواقع في المنطقة الجنوبية الشرقية من الحوض ما يشكل حفرة بالوعية (hole sink) هناك. بالاعتماد على النتائج السابقة يوصى بتصميم آبار الحوض وينابيعه بدقة واستمرارية وكذلك الحال فيما يتعلق بتشغيلها وعملها، ويوصى كذلك بتقييم تأثير الفوالق والانكسارات على قيم النفاذية.
    MODFLOW
    Groundwater model
    Aquifer test
    Groundwater discharge
    Cone of depression
    Aquifer properties
    Citations (2)
    First posted December 16, 2020 For additional information, contact: Director, New England Water Science CenterU.S. Geological Survey10 Bearfoot RoadNorthborough, MA 01532 A three-dimensional groundwater-flow model was developed for the aquifer system of Long Island, New York, to evaluate (1) responses of the hydrologic system to changes in natural and anthropogenic hydraulic stresses, (2) the subsurface distribution of groundwater age, and (3) the regional-scale distribution of groundwater travel times and the source of water to fresh surface waters and coastal receiving waters. The model also provides the groundwater flow components used to define model boundaries for possible inset models used for local-scale analyses.The three-dimensional, groundwater flow model developed for this investigation uses the numerical code MODFLOW–NWT to represent steady-state conditions for average groundwater pumping and aquifer recharge for 2005–15. The particle-tracking algorithm MODPATH, which simulates advective transport in the aquifer, was used to estimate groundwater age, delineate the areas at the water table that contribute recharge to coastal and freshwater bodies, and estimate total travel times of water from the water table to discharge locations.A three-dimensional, 1-meter (3.3-foot) topobathymetric model was used to determine land-surface altitudes for the island and seabed altitudes for the surrounding coastal waters. The mapped extents and surface altitudes of major geologic units were compiled and used to develop a three-dimensional hydrogeologic framework of the aquifer system, including aquifers and confining units. Lithologic data from deep boreholes and previous aquifer-test results were used to estimate the three-dimensional distribution of hydraulic conductivity in principal aquifers. Natural recharge from precipitation was estimated for 2005–15 using a modified Thornthwaite-Mather methodology as implemented in a soil-water balance model. Components of anthropogenic recharge—wastewater return flow, storm water inflow, and inflow from leaky infrastructure—also were estimated for 2005–15. Groundwater withdrawals for various sources, including public water supply, industrial, remediation, and agricultural, were compiled or estimated for the same period.These data were incorporated into the model development to represent the aquifer system geometry, boundaries, and initial hydraulic properties of the regional aquifers and confining units within the Long Island aquifer system. Average hydraulic conditions—water levels and streamflows—for 2005–15 were estimated using existing data from the U.S. Geological Survey National Water Information System database. Model inputs were adjusted to best match average hydrologic conditions using inverse methods as implemented in the parameter-estimating software PEST. The calibrated model was used to simulate average hydrologic conditions in the aquifer system for 2005–15.About 656 cubic feet per second of water was withdrawn on average annually for 2005–15 for water supply and an average of about 349 cubic feet per second of water recharged the aquifer annually from return flow and leaky infrastructure. Parts of New York City have drawdowns exceeding 25 feet, mostly because of urbanization and associated large decreases in recharge rates. Large areas in the western part of the island have drawdowns exceeding 10 feet, mostly from large groundwater withdrawals and sewering, which largely eliminates wastewater return flow. Water-table altitudes in eastern parts of the island increased by more than 2 feet in some areas as a result of wastewater return flow in unsewered areas and changes in land use. Changes in streamflows show a similar pattern as water-table altitudes. Streamflows generally decrease in western parts of the island where there are large drawdowns and increase in eastern parts of the island where water-table altitudes increase.
    MODFLOW
    Groundwater model
    Groundwater discharge
    Surficial aquifer
    Aquifer test
    Piezometer
    Cone of depression
    Hydraulic head
    Citations (13)