Solutions for groundwater flow with sloping stream boundary: analytical, numerical and experimental models

Abstract Protecting groundwater resources plays an important role in watershed management. For this purpose, studies on groundwater flow dynamics incorporating surface water–groundwater interactions have been conducted including analytical, numerical, and experimental models. In this research, a stream–aquifer system was considered to understand the physical behavior of surface water–groundwater interactions. Interactions in a stream–aquifer system were incorporated into the mathematical modeling by defining the stream head as a boundary condition for the groundwater flow equation. This boundary was chosen as a sloping stream boundary, which is an approach in representing the natural conditions of the stream and may be used to define continuous interactions between stream and aquifer. A semi-analytical solution for transient 2D groundwater flow was developed for the considered problem. Isotropic, homogeneous, and finite aquifer assumptions were made in order to define the aquifer characteristics. Then, a series of laboratory experiments was conducted to simulate this stream–aquifer system. Finally, a numerical model was developed by using Visual MODFLOW to verify analytical and experimental results. Numerical results matched with both analytical solutions and the experimental observations.

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3D modelling of a hydrological structure combining spatial data science and geophysics: Application to a coastal aquifer system in the island of Crete, Greece

10.5194/egusphere-egu21-2601 ◽

2021 ◽

Author(s):

Emmanouil Varouchakis ◽

Leonardo Azevedo ◽

João L. Pereira ◽

Ioannis Trichakis ◽

George P. Karatzas ◽

...

Keyword(s):

Climate Change ◽

Groundwater Flow ◽

Spatial Data ◽

Coastal Aquifer ◽

Data Science ◽

Flow Model ◽

Groundwater Resources ◽

Geostatistical Simulation ◽

Groundwater Flow Model ◽

Aquifer System

Groundwater resources in Mediterranean coastal aquifers are under threat due to overexploitation and climate change impacts, resulting in saltwater intrusion. This situation is deteriorated by the absence of sustainable groundwater resources management plans. Efficient management and monitoring of groundwater systems requires interpreting all sources of available data. This work aims at the development of a set of plausible 3D geological models combining 2D geophysical profiles, spatial data analytics and geostatistical simulation techniques. The resulting set of models represents possible scenarios of the structure of the coastal aquifer system under investigation. Inverted resistivity profiles, along with borehole data, are explored using spatial data science techniques to identify regions associated with higher uncertainty. Relevant parts of the profiles will be used to generate 3D models after detailed Anisotropy and variogram analysis. Multidimensional statistical techniques are then used to select representative models of the true subsurface while exploring the uncertainty space. The resulting models will help to identify primary gaps in existing knowledge about the groundwater system and to optimize the groundwater monitoring network. A comparison with a numerical groundwater flow model will identify similarities and differences and it will be used to develop a typical hydrogeological model, which will aid the management and monitoring of the area's groundwater resources. This work will help the development of a reliable groundwater flow model to investigate future groundwater level fluctuations at the study area under climate change scenarios.&#160;This work was developed under the scope of the InTheMED project. InTheMED is part of the PRIMA programme supported by the European Union&#8217;s Horizon 2020 research and innovation programme under grant agreement No 1923.

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GROUNDWATER CONCEPTUAL MODEL FOR PADDY IRRIGATION

Jurnal Teknologi ◽

10.11113/jt.v78.7278 ◽

2015 ◽

Vol 78 (1-2) ◽

Cited By ~ 1

Author(s):

Ahmad Fikri Abdullah ◽

Wan Amirul Wan Mustapa

Keyword(s):

Groundwater Flow ◽

Conceptual Model ◽

Root Zone ◽

Groundwater Resources ◽

Visual Modflow ◽

Alternative Source ◽

Aquifer Storage ◽

Paddy Irrigation ◽

Rice Irrigation ◽

Current Water

Hydrological modelling is representative of current, past or future hydrologic balance. It has been used widely in water-related problem such as drought, flood, water contamination and irrigation. Crops irrigation requires a lot of water to irrigate the root zone layer especially for paddy crops. With the current issues of water such as drought and pollution, an alternative source is needed to overcome the problem of water scarcity. Generally Malaysia depends on the surface water to irrigate the crops with no aided of groundwater. This study focuses on the availability of groundwater resources to irrigate the paddy crops. Hence, a conceptual model of groundwater flow was developed to shows the current situation of the groundwater flow at the study area. Several models were developed to see if groundwater can be extracted using wells and be used as an alternative source for irrigation. The study area is located at Sawah Sempadan, which is one of Malaysia’s greeneries areas under Tanjung Karang Rice Irrigation Scheme (TAKRIS). The conceptual model is built by using Visual MODFLOW 4.2. The conceptual model shows the current water balance, water table elevation and equipotential head in the study area. Simulations with pump wells have been done to shows the availability of groundwater sources for paddy irrigation. The result shows that groundwater flows from area of higher elevation towards the lower elevated area. It is also shows that groundwater extraction could not be too excessive as it may dry up the aquifer storage.

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Envisaging the Sustainability of an Aquifer by Developing Groundwater Flow Model for a Part of ChoutuppalMandal, Nalgonda District, Telangana, India

Nepal Journal of Science and Technology ◽

10.3126/njst.v19i1.29824 ◽

2020 ◽

Vol 19 (1) ◽

pp. 222-233

Author(s):

P. K. Neupane ◽

N. C. Mondal ◽

A. Manglik

Keyword(s):

Drinking Water ◽

Groundwater Flow ◽

Flow Equation ◽

Visual Modflow ◽

Fractured Aquifer ◽

Pumping Rate ◽

Groundwater Levels ◽

The North ◽

Weathered Layer ◽

Nalgonda District

Recurring droughts and increased exploitation of groundwater to meet the growing water needs have resulted in the decline of regional groundwater level and dry, weathered zone in a part of the Choutuppal Mandal, Nalgonda district, Telangana, India. A groundwater model has been developed using an inventory of 20 observation wells for future pumping schemes to evolve a classic interface (Build: 4.6.0.168) of available wells. The developed model has been reviewed using Visual MODFLOW, and a base map is prepared for the sub-surface structure. The area spreading about 0.43 km2is conceptualized as a two-layered model consisting of a weathered layer overlying a fractured aquifer. The model has been digitized into grids of 5m×5m in each layer. The integrated finite difference method has been utilized to discretize the groundwater flow equation and simulate groundwater flow with the help of calculated parameters along with the boundary conditions and acting stresses. Results show that the computed groundwater levels are in good agreement with the observed heads, and groundwater is flowing from the South to the North direction. The estimated velocities vary from 0.01 to 1.95 m/d. The optimum pumping schemes have also been simulated up to the year 2022. It has been observed that the maximum pumping rate should not go beyond 24m3/day. Since the drinking water demand(10-15m3/day) in the study site is below this limit, it can be inferred that the aquifer will sustain and provide enough drinking water.

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Lateral groundwater flow and pond interactions during dry and wet years

SURG Journal ◽

10.21083/surg.v9i1.3821 ◽

2017 ◽

Vol 9 (1) ◽

pp. 27-39

Author(s):

Andrew Wicke ◽

Thair Patros ◽

Gary Parkin

Keyword(s):

Surface Water ◽

Groundwater Flow ◽

Flow Direction ◽

Unconfined Aquifer ◽

Hydrologic Cycle ◽

Future Climate Change ◽

Visual Modflow ◽

Evaporative Demand ◽

Monitoring Wells ◽

Tightly Coupled

Groundwater and surface water are tightly coupled elements of the hydrologic cycle that have often been treated as separate entities. Future climate change modelling has predicted that hydrologic cycle changes, namely increasing drought frequency and flood-type events, are likely to occur. These events may directly impact the quality and quantity of both groundwater and surface water. Future water management policies must therefore be based on an understanding of how interactions between groundwater and surface water will change with a warming climate. The aim of this study was to model and analyze the lateral flow of groundwater and its interactions with a nearby pond in a shallow, unconsolidated, unconfined aquifer. Data were collected as part of a larger and ongoing study during the year 2012, a comparatively dry year, and 2013, a comparatively wet year. We first used ArcGIS and Visual MODFLOW Flex to create a conceptual model of the system, its soil layers, monitoring wells, and potential flow patterns. We then analyzed hydraulic head data, and calculated groundwater flow volumes using the Dupuit equation. We found that the groundwater flow direction reversed in the summer of 2012 and continued until the spring of 2013. Additonally, flow rate was greater in 2013 than 2012. The flow reversal was likely caused by higher evaporative demand during the summer months of 2012, drawing substantially more water from the pond than from the soil. The two-year timeframe was not long enough to determine whether this was a typical, yearly pattern, or was primarily due to the fact that 2012 was a particularly dry year.

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APPLICATION OF FEFLOW FOR THE SIMULATION OF GROUNDWATER FLOW AT THE TIRNAVOS (CENTRAL GREECE) ALLUVIAL BASIN AQUIFER SYSTEM

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.11360 ◽

2017 ◽

Vol 43 (4) ◽

pp. 1747 ◽

Cited By ~ 1

Author(s):

I. Koukidou ◽

A. Panagopoulos

Keyword(s):

Groundwater Flow ◽

Groundwater Resources ◽

Negative Effects ◽

Simulation Code ◽

Aquifer System ◽

Practical Applications ◽

Central Greece ◽

Field Data Analysis ◽

The Mathematical Model ◽

First Time

FEFLOW is a relatively new simulation code that was applied and tested systematically for the first time in Greece at Tirnavos alluvial basin, which is part of the eastern Thessaly plain. The aim of this exercise is to apply and test the applicability and versatility of FEFLOW in the simulation of groundwater flow of the Tirnavos basin aquifer system, which is located in eastern Thessaly-central Greece. From the compilation and calibration of the mathematical model, it can be concluded that FEFLOW is a very powerful tool with many practical applications and capabilities. Application of FEFLOW at Tirnavos basin was successful. As deduced by field data analysis, groundwater resources of the study area are overexploited, a fact which bears negative effects not only for the study area, but also for the surrounding area, which is much greater in extent. This fact was well reproduced in the simulation. It is therefore of utmost importance to rationally manage regional groundwater resources aiming at aquifer restoration (quantity and chemical quality) and the environmental protection of both the aquifer system and the depended and interrelated ecosystems, in accordance to the water related EC Directives.

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The precarious freshwater resources of Sable Island, Nova Scotia, Canada: Occurrence and management considerations

Proceedings of the Nova Scotian Institute of Science (NSIS) ◽

10.15273/pnsis.v48i2.6662 ◽

2016 ◽

Vol 48 (2) ◽

pp. 331

Author(s):

Terry W. Hennigar ◽

Gavin W. Kennedy

Keyword(s):

Drinking Water ◽

Nova Scotia ◽

Surface Water ◽

Groundwater Resources ◽

Sustainable Use ◽

Fresh Groundwater ◽

Freshwater Resources ◽

Aquifer System ◽

Quality Of Water ◽

Source Water Protection

This paper presents an overview of the hydrogeology and the freshwater resources of Sable Island, Nova Scotia. The role of the sand deposits, morphology and dynamics of the dune structures and systems, precipitation, and tidal influences are discussed. The distribution, quality, and importance of both surface water and groundwater resources of the island are also presented. Fresh groundwater on the Island occurs in an unconfined sand lens aquifer. Studies to date on the hydrogeology of the island have shown highly variable rates of precipitation, both seasonally and annually, which in combination with the influence of shifting dune structures contribute to a dynamic freshwater /saltwater balance. Infiltration rates into the permeable aquifer system are greater than precipitation rates, precluding surface water flow.The chemical quality of water in the freshwater lens aquifer is generally good and meets the Guidelines for Canadian Drinking Water Quality. The aquifer is vulnerable to surface contamination, however, due to its shallow, unconfined nature, and any water supply wells are highly likely to be classified as being ‘under the direct influence of surface water’ (GUDI). Under these conditions a multi-barrier source water protection plan is considered essential for managing future public drinking water supplies on the Island. Recommendations for future studies, including long-term monitoring of water level trends, are provided to support the sustainable use of groundwater on the Sable Island.

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An analytical study of groundwater fluctuations in unconfined leaky aquifers induced by multiple localized recharge and withdrawal

Global NEST Journal ◽

10.30955/gnj.001037 ◽

2013 ◽

Vol 15 (3) ◽

pp. 394-407 ◽

Cited By ~ 7

Keyword(s):

Groundwater Flow ◽

Numerical Models ◽

Temporal Distribution ◽

Neumann Boundary ◽

Unconfined Aquifer ◽

Flow Equation ◽

Aquifer System ◽

Fourier Cosine ◽

Induced Flow ◽

Vertical Leakage

Commonly used analytical methods for assessing the effects of recharge and withdrawal on the groundwater flow system are based on an idealistic assumption that the aquifer’s base is fully impervious. In reality, the hydrostratigraphic conditions are often complex and involve leakage induced flow between aquifer and the confining layers. In this study, a simple analytical procedure is presented for determining the spatial and temporal distribution of water head in an unconfined aquifer system due to multiple localized recharge and withdrawal at time-varying rates. A new transient function is introduced that can conveniently approximate the rising and recession limbs of any single recharge hydrograph. Solution of linearized two-dimensional groundwater flow equation under Dirichlet and Neumann boundary conditions is obtained using finite Fourier cosine transform with analytic inversion. The study has at least one clear advantage over the existing solutions that it accounts for the vertical leakage in water table buildup and drawdown analysis. A computational example demonstrates that the leakage induced flow plays an important role in recharge and withdrawal processes of unconfined aquifer system. The model results can be used for estimating aquifer’s hydraulic properties and validation of numerical models.

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

Anuário do Instituto de Geociências - UFRJ ◽

10.11137/1982-3908_2021_44_39646 ◽

2021 ◽

Vol 44 ◽

Author(s):

Milena Stefany Lage Almeida ◽

JOSÉ AUGUSTO COSTA GONÇALVES

Keyword(s):

Boundary Conditions ◽

Groundwater Flow ◽

Root Mean Square ◽

Flow Behavior ◽

Groundwater Resources ◽

Absolute Error ◽

Mean Square ◽

Visual Modflow ◽

Porous Aquifer ◽

The Mean

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.

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Modeling of groundwater flow velocity and aquifer recharge in a Cenozoic multi-aquifer system – a case study from Eastern Brandenburg (Germany)

10.5194/egusphere-egu2020-21667 ◽

2020 ◽

Author(s):

Silvio Janetz ◽

Christoph Jahnke ◽

Frank Wendland ◽

Hans-Jürgen Voigt

Keyword(s):

Groundwater Flow ◽

Groundwater Resources ◽

Turnover Time ◽

Aquifer Recharge ◽

Deep Groundwater ◽

Near Surface ◽

Aquifer System ◽

Deep Aquifers ◽

Regional Flow ◽

Flow Processes

In recent years, deep aquifers (> 50 m below ground level) have become increasingly interesting for the supply of drinking and irrigation water or geothermal use. Understanding the regional flow processes between near-surface and deep aquifer systems is an important criterion for the sustainable management of deep groundwater resources. However, hydrogeological conditions, regional flow rates and aquifer recharge in deep aquifers are largely unknown in many cases. The aims of the present study are therefore to determine (i) groundwater flow velocities in a Cenozoic multi-aquifer system, and (ii) proportion of aquifer recharge into the individual Cenozoic aquifers and timescales to completely replace water in the Cenozoic aquifers (turnover time). &#160;The numerical study was carried out in three adjacent groundwater catchment areas in the region of Eastern Brandenburg. In a first step, a hydrogeological 3D model of the entire Cenozoic aquifer system (85 km &#215; 73 km and down to a depth of 0.5 km) was developed, which comprises up to 12 unconsolidated sandy aquifers and 10 confining units (glacial tills, silts and clays). In a second step, a steady-state flow modelling was performed including calibration using natural hydraulic head data from both regional main and deep aquifers.The modeling results show that the average groundwater flow velocities decrease from 20-50 m/a in the near-surface Pleistocene main aquifers to 1-2 m/a in the deep Oligocene aquifers. At the same time, the aquifer recharge in the aquifer system decreases substantially with increasing depth. Depending on the catchment geology, the Pleistocene main aquifers are recharged by 65-70 % of infiltration water, while the aquifer recharge of the deep Oligocene aquifers is only 4.5-9.5 %. The calculations of turnover time indicate that the time periods to completely flush the deep aquifers are very long (approx. between 90 and 4600 years). The results thus allow a first quantification of the flow processes between near-surface and deep aquifers as well as the identification of flow paths to develop a utilization concept for deep groundwater resources in the region of Eastern Brandenburg.

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Constructing a 3D geological model from geophysical data for groundwater modelling and management in the Kribi-Campo sedimentary sub-basin, Cameroon

Water Practice & Technology ◽

10.2166/wpt.2020.004 ◽

2020 ◽

Vol 15 (1) ◽

pp. 105-119 ◽

Cited By ~ 1

Author(s):

Gah-Muti Salvanus Yevalla ◽

Biyong Bi Mback Emmanuel Blaise ◽

Rodrigue Ebonji Seth ◽

Étienne Totcha Beka ◽

Tabod Charles Tabod

Keyword(s):

Positive Impact ◽

Groundwater Resources ◽

Current Model ◽

System Structure ◽

Geological Model ◽

Infrastructure Development ◽

Visual Modflow ◽

Hydrogeological Model ◽

Aquifer System ◽

3D Geological Model

Abstract Groundwater resources along the coast of Cameroon (Kribi–Campo Sub-Basin) are under siege from point and non-point pollution sources, climate change, urbanization and infrastructure development. This situation is made worse by the absence of a water management and development strategy. Managing and monitoring the area's water resources requires an understanding of the groundwater systems, and thus a thorough understanding of the geology. In this study, a 3D geological model was built from electro-seismic data and the structure of the area's aquifer system developed. The aquifer system structure was transferred into Visual MODFLOW Flex and then used to develop a typical hydrogeological model, which will help the management and monitoring of the area's groundwater resources. As more geological data become available, the current model can be updated easily by editing and recomputing. This work is expected to have a positive impact quite quickly on the provision of potable water and on public health.

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